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1. 282 Average Settling AlgorithAM 282 Settling Tolerance conciso kee eens Aa 282 Settling FIOO AE 282 Settling Issues for Specific Instruments 283 TINMCOUL sarac rerai ese ones sas 283 Chapter 16 OPADOS s 6 eh bee cres asesora as 285 The Graph RNE per eee ed be read 285 ZOON nau gea ea heen eee eae eh Seay eee ee 286 The Graph Options MENU 2 lt 4 822 ae eee bw ee wes 287 ZOOMQUE o Gane ee ee eee es eee ee ee eee 287 ZOOMQUETO Original as eee AAA 288 OptiMIZe ek te bn ee eee de Chee Hee RH eee EG 288 Copy TO Sweep Panel se ku eb k GREK RES RHE HES 289 Display CUISOIS 244 oeiwn ee ne ede ada 289 SCO GOS nenas sr be aes ee eee RSS 292 Title and Labels ps e Boe ws hee ee ee ee ee 293 COMMEN 2er cuca arar 293 NOW Dat aseos nosotras 293 Graph Buffer ona eu eee Mew es er a ee Ae 294 Ao ECOG e s icr i seraa a eed ee ke woe eee eS 294 Graph Legend Data Editor Linkage 296 Graphing invalid or suspect data 298 WAC COIOIS lt esposos eh Oe eS Soe oe eS 298 Color Assignment foraNewTest 299 Color Assignment for Multiple Data Set Sweeps 299 Color Cycling in Nested and Appended Sweeps 299 Color Cycling with Appended Files 300 xii ATS 2 User s Manual Chapter 17 Bar Graphs 0200 303 CreatingaBarGraph 2 200 303 BarGraphSetup
2. 10 X vs Y data plot 263 X axis graph divisiONS 261 Y axis graph divisiONS 263 ZOO oem be eee eS me es 286 439 Index BO ATS 2 User s Manual
3. 229 Tight NormalandLoose 229 Trig AE 230 Trigger Delay 02 002 ee eee ee 230 Phase Measurements 2 05804 230 ChannelAPhase 2 0 0505 b ee 231 ChannelBPhase 2 00 505804 231 References 231 Other Considerations 2 208 232 Multitone Minimum Duration Requirements 232 Invalid Multitone Readings 233 Acquired Waveform Files 2 4 233 Saving Acquired Waveforms 234 Opening Acquired Waveforms 234 Combining Mono to Stereo 235 Compatibility of Acquired Waveform Files 235 Creating Multitone Waveform Files 236 Multitone Creation Utility opening dialog box 236 Using Existing FileData 238 FileOptions 0 000 eee eee 239 Frequencies Menu 5 240 Editing the Frequency List 240 Sweep Table Definition 241 Creating an MS RIFF wawW File 242 FinalOptions 0 00 eee eee 243 Chapter 14 The Harmonic Distortion Analyzer 245 Introduction 2 000 bee eee eee 245 Loading the Harmonic Distortion Analyzer 247 SignalInoputs 0200 bee eee eee 247 The Fundamental Amplitude Meters 248 The Fundamental Frequency Meters 24
4. Squarewave Analog Generator Digital Generator Standard toolbar Status bits consumer format CRO os aueue aos hex control and display in dual connector mode local address and time of day panel lt lt 46088 6 amp ee es 4 professional format transmit Stepsize Regulation setting Stereo sine waveforms Stereo sweep setting Stop sweepcommand Subframe digital audio signal sweep overview 438 Sweep display mode 265 Sweep file 310 Sweep panel aooo a a a a a a a aa 258 Sweep planning 257 Sweep Reprocess Datacommand 287 Sweep resolution 260 Sweep settling concepts oaao a a a a 280 delay time 280 PANEL a a ea ame e ea SS RS 279 Sweep Settling OVerV eEW aaa a a a a 278 Sweep table for a multitone file 241 Sweep track tuned filter see bandpass bandreject filter Sweep graph and table relationship 255 Sweeps tiMe 277 SVACIADUE a6 one ae be as 341 Sync Ref IN 6 amp dus 4 we a wa ee a 341 rear panel connector 2 2 34 Sync Ref Input panel 342 Sync Ref squarewave frequency 343 Synchronous FFT 399 T 2 channel ratio measurements Audio Analyzer 132 T timeout flag see Data Editor timeout flag
5. The Frequency and Frequency 2 fields permit each component sinewave frequency to be set independently The Dual Ampl Ratio field enables you to set the ratio by which the secondary Frequency 2 sinewave component amplitude will be attenuated with respect to the am plitude of the primary Frequency sinewave component The Sine Dual signal is particularly useful as a calibration signal for harmonic distortion analyzers where the Frequency signal at reference amplitude represents the fundamental signal The secondary Frequency 2 sinewave can be set to any desired harmonic of the primary Fre quency fundamental sinewave at an amplitude to represent any de sired distortion level For example setting the primary Frequency at 1 kHz and the secondary Frequency 2 at 3 kHz with a Dual Amp Ra tio of 40 0 dB 1 produces a 1 kHz signal with third harmonic distor tion of 1 0 Wfm Sine Shaped Burst Figure 80 Digital Generator Sine Shaped PMI Burst wim Sine a Shaped Burst Freguency 957001 kHz Lh A ChB Burst Onf Cycles Interval 3 Cycles h Low i ON O mete eee Auto O un Track A fi OOO FFS Ti Amplitude rE A tone burst is an audio signal usually a sinewave that is keyed on and off Tone bursts are often used as stimulus signals and can reveal character istics of a DUT s performance which are not observable with continuous tones The Digital Generator Sine Shaped Burst signal
6. 146 CCITT weighting filter see weighting filter 146 Center Compute algorithm 322 Changing data with Compute 317 Channel selection Analog Generator 79 Digital Generator 101 Channelstatusbit 386 see Status bits 70 Chart recorder sweep mode 277 Clock jitter measurement 206 CMT see common mode testing 128 Color trace 248 298 Colorcycle 298 Colors configuration 366 Comment graph 293 Common mode testing coupling issues 128 Compute algorithms Average 8 324 Center aaa a a 322 comparing with orig data 327 E E E oe 323 Equalize 326 Invert aoaaa a 320 Linearity aoaaa aa a a 321 Maximum 325 Minimum 325 Normalize 4 siria 319 overview 317 SMOOT se sa ava d ie deeban dee 320 Compute Status list 326 Configuration COIO Soja sisas 366 general 362 o E bdas 366 Log file isos aa A 364 OVOIV IOW 361 trace 2 048 366 Connection bargraph 305 Constant Value waveform 120 Consumer format digital interface 384 Copy a window panel or screen to clipboard 334 graph to clipboard 334 ATS 2 Use
7. 0 000 dB 8 239 dBr 8 239 dBrlri 0398606 dec FFFFFE hex 000 kHz If the Track A checkbox is checked the audio amplitude of both Chan nel A and Channel B are set by the Channel A Amplitude setting If the Track A checkbox is not checked the audio amplitudes of the two Digital Generator channels can be controlled individually Type a value in the Amplitude setting field for either Channel A or Channel B and press Enter You can choose an amplitude unit of measurement in either the analog or digital domains from the units drop down list shown in Figure 73 The ability to state a digital audio amplitude in analog terms makes it easy to work with the analog output values while testing a D to A converter for ex ample when the full scale analog output of that converter is known Enter the DUT voltage which corresponds to digital full scale in the References Volts FS field see page 122 ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator Changing a unit of measurement will not change the audio amplitude only the expression of the value See Digital Amplitude Units page 376 and Analog Amplitude Units page 372 The value displayed after pressing Enter may differ slightly from the value you typed in since ATS will step to the nearest amplitude increment The Digital Generator will not permit an output amplitude entry greater than 1 000 FFS 0 dBFS If you enter a value gre
8. Audio Precision ATS 2 User s Manual udio Audion DIGITAL OUTPUT Clay E Or ene E or ATS Software Version 1 6 Copyright 2001 2007 Audio Precision Inc All rights reserved Document part number 8211 0135 revision 4 All content in this manual is owned by Audio Precision and is protected by United States and international copyright laws Audio Precision allows its customers to make a limited number of copies of this manual or portions thereof solely for use in connection with the Audio Precision product covered by this manual Audio Precision may revoke this permission to make copies at any time You may not distribute any copies of the manual apart from a transfer of ownership of the Audio Precision product Audio Precision System One System Two System Two Cascade System One DSP System Two DSP Dual Domain FASTTEST APWIN ATS and ATS 2 are trademarks of Audio Precision Inc Windows is a trademark of Microsoft Corporation Published by 5750 SW Arctic Drive Beaverton Oregon 97005 503 627 0832 o 1 800 231 7350 Precision 32 ap com Printed in the United States of America VI10807112021 Safety Information gt gt stos AAA XIX SafetySymbols 0 000 ete eee ee eee XX Chapter 1 Introduction 0280048 1 ATS 2 an Overview 0 000 cee eee a 1 APIB 2 a a a a a a aa 2 GPIB 246k oe ooh a a rs a a e 2 About Th
9. ATS 2 User s Manual 367 Chapter 25 Configuration and the Utilities Menu Hardware Status 368 Hardware Status Figure 283 The ATS System Status and Information Hardware Status panel The Utilities gt Hardware Status command opens the System Status and Information dialog box which reports a number of ATS and ATS 2 conditions Turn All Outputs OFF ON The Utilities gt Turn All Outputs Off issues the same command as the function key F12 the panic button Either of these turns off all gener ator outputs The Utilities gt Turn Outputs Back On issues the same command as the key combination Ctrl F12 Either of these turns on any generator outputs previously turned off by the panic button Clear Log File This command clears all the information from the log file It does not de lete the file but leaves it empty See The Log File on page 364 View Log File This command opens the log file in Notepad for viewing or printing See The Log File on page 364 ATS 2 User s Manual Learn Mode Chapter 25 Configuration and the Utilities Menu Learn Mode Learn Mode records every appropriate operation of the ATS software to an AP Basic macro file It is similar to features in other applications called macro recorders Learn Mode is often the easiest way to create a macro Choose Utilities gt Learn Mode to enter Learn Mode An AP Basic macro will open in the Macro Editor and each ATS setting you make is en te
10. En e e xi Blue Solid Analyzer Level B Left When a test file is opened the first display will be the traces from the loaded test using the colors saved in that file If new sweeps are appended to this test by sweeping with the Append box checked the colors assigned to the appended sweeps traces depend on a Configuration setting m Ifthe Use Test Colors Only checkbox on the Graph tab of the Configuration panel is unchecked the trace colors will rotate through the color cycle using the test colors as the starting point m Ifthe Use Test Colors Only checkbox is checked color cycling is disabled and each appended trace will maintain the trace color loaded in the test See Chapter 25 Configuration Color Cycling with Appended Files When a current sweep is appended with sweep data from disk using the File gt Append command the colors assigned to the sweep traces from the appended file depend on a Configuration setting m Ifthe Cycle Trace Colors checkbox on the Graph tab of the Configuration panel is unchecked the appended file trace colors will come in without change 300 ATS 2 User s Manual Trace Colors Chapter 16 Graphs m If the Cycle Trace Colors checkbox is checked the colors of the traces appended from disk will move through the color cycle using the last set of traces currently in memory as the starting point See Chapter 25 Configuration ATS 2 User s Manual 301 Chapter 16 Grap
11. ATS reads and sets all Channel Status conditions but does not display or set User bits Channel Status The Channel Status information differs substantially between the profes sional and the consumer formats The first bit in the block indicates profes sional format by a O and consumer format by 1 The following tables show the channel status fields and their interpreta tions for both the professional and consumer formats Byte Consumer format channel status fields Pro con Non Copyright Channel status 0 audio 0 mode 00 2 Channel number 21 22 Clock accuracy O 26 28 29 30 31 Word length Future original sampling frequency 34 35 36 37 38 39 Reserved bits 40 191 386 ATS 2 User s Manual The Serial Digital Interface Signal Appendix B The Digital Audio Signal Consumer format channel status field interpretations pro con 0 consumer 1 professional format non audio 0 suitable for conversion to analog audio using linear PCM 1 not suitable copyright 0 asserted 1 not asserted emphasis 000 Emphasis not indicated 100 emphasis CD type channel status mode 00 mode zero other values reserved category code The category code depends on the equip ment type For most codes the MSB of the category code carries information about generation status of the material refer to SCMS and is called the L bit The following are common codes LSB MSB General 0000 000L Laser Optical 100x xxxL D D Conve
12. Quick Launch toolbar 24 R regulation flag see Data Editor regulation flag Random waveform 120 Ranging meter Audio Analyzer 129 function Meter 140 Rate Ref a6 ds ha eS Bowe e ESS 66 Ratio measurements level see 2 channel ratio measurements Ratio UMIES esoo eee eo ag we Ros 378 Reading rate function meter detector 142 Real time sweeps 257 oo vs batch mode measurements 43 Rectangular probability distribution function see dither Reference Input 341 Reference Input Source 343 Reference Rate Digital see Rate Ref ATS 2 User s Manual Reference trace cesa References Analog Generator aaa Audio Analyzer analog input Audio Analyzer digital input Digital Generator Digital Interface Analyzer Harmonic Distortion Analyzer Multitone Audio Analyzer Regulation algorithms examples of regulated sweeps OVO VICWS gt vag Ke oR we wee a panel selections Relative units Repeat sweep setting Reprocess Data see Sweep Reprocess Data command Resolution sweep Rife Vincent FFT window RMS detector see detector function meter RPDF see dither S for arbitrary waveform files for pass thru feature Saving test data Scale frequency NDUT os a ces reni
13. Table sweeps 270 310 Table sweep and graph relationship 255 Table sweep display mode 265 Target Range bargraph 305 Target Regulation parameter 356 Terminate sweep on failure 314 Test Cala oa os 2 ee ae Ro ee RS 308 Test translator 418 TADEFN 0 2 2 808 134 amplitude measurements 136 ratio measurements 135 Time sweeps 2 277 Time units eae eO REDDER oO 380 Time domain view see Spectrum Analyzer Timeout per step Regulation setting 358 TES Olay y an ee aaa AO A 293 Tolerance SEUNG e 4 s eea i Bee e aS 282 Tolerance Regulation parameter 356 TONE DUNST eee we eee eS ee ee 84 106 Top values sweep data 262 Total harmonic distortion plus noise see THD N TPDF see dither ATS 2 User s Manual Trace color cycle 1 ea ee ee ee eS 298 5 O 298 configuration ss Kae 4a ooo eH oS 366 PErerenCe 2 445464 4455 pias 294 selection for printing 331 Triangular probability distribution function see dither Trigger Digital Interface Analyzer 209 Multitone Audio Analyzer 229 Trigger In and Out rear panel connectors 34 Trigger output 345 Tuning bandpass or bandreject filter see bandpass bandreject filter Tuning notch or peaking filter see bandpass bandreject filter U upper limit flag see Data Editor u
14. Transform Length Figure 132 ATS FFT transform length 1 000 FFS Peak M v 00 FFS z selections pa l FFT 18192 F Acquire Track FFT hdd sub 1 2 pk pl The transform length and sample rate determine the bin width or fre quency resolution of an FFT See Appendix C for a conceptual overview of FFTs including a discussion of the relationship between transform length sample rate and bin width Select an FFT length from the FFT list Your choices are 256 512 1024 2048 4096 8192 16384 and 32768 samples When you are performing an FFT on an acquisition record which is lon ger than the transform length only the number of samples specified in the FFT field will be transformed Spectrum Analyzer Window Selection Figure 133 ATS Spectrum Analyzer FFT window E quiripple sub 1 2 pk pl z Window selections Blackman H arris Hone FFT Hone move to bin center 1 Rife vincent 4 AiteWIncent 5 Caune F ENEE See Appendix C for a conceptual overview of FFTs including basic in formation on FFT windowing The window selections for the Spectrum Analyzer are m Blackman Harris Hann m Flat top Equiripple None ATS 2 User s Manual 161 Chapter 11 The Spectrum Analyzer Spectrum Analyzer Window Selection 162 None move to bin center u Hamming Gaussian Rife Vincent 4 and Rife Vincent 5 Each window function has a different set of trade offs in effective selec
15. 131 2 Channel Ratio Function 132 Crosstalk Function 2804 133 THD N Functions 02 048 134 THD N Ratio Function 135 THD N Amplitude Function 136 Bandpass Function 136 SMPTE DIN IMD Function 137 Phase Function aooaa aaa a a a a a a a a a 138 Function Meter UnitS ooa aa a a a a a a aa a 140 Function MeterRanging 140 Detector Type aoaaa aa a a a a a a a a a a a 141 Detector ReadingRate 142 The Bandwidth and Filter Fields 143 BW The Highpass Filter 143 BW The Lowpass Filter 144 The Fltr Field 145 ATS 2 User s Manual Fitr Weighting Filters USOr FIIEGIS oe Baan oe eee bee A A Bandpass Bandreject Filter Tuning Fitr Selecting Harmonics in Bandpass RETErCNCeS osea ee use o e bee ees ee eS Analyzer Analog References Analyzer Digital References Chapter 11 The Spectrum Analyzer INEFOGUCTIONS s a s ee an eee eee ee oe eRe eee es Loading the Spectrum Analyzer SIGNALING s s a sws eee ee ARRE Peak Level Monitors 0 Acquiring Transforming and Processing The Acquisition Reco
16. ATS 2 User s Manual 123 Chapter 10 The Audio Analyzer Loading the Audio Analyzer This chapter examines each function control and display of the Audio Analyzer in detail If you are new to ATS 2 you might want to start with the Quick Guides in Getting Started with ATS 2 which will introduce you to Audio Analyzer features The Audio Analyzer will measure either digital or analog domain au dio input signals as selected by the Input field It is a two channel instru ment capable of performing measurements on both channels of a stereo signal at the same time For an analog signal the Audio Analyzer can measure a frequency range from DC to about 0 45 x F where Fs is the sample rate of the inputs ADCs set on the Analog Input panel for digital signals the Audio Analyzer can measure a frequency range from DC to O05 F There are three pairs of meters on the Audio Analyzer which measure the input signal simultaneously m the Level meters m the Freq frequency meters and the Function meters As on other ATS panels you can select the units of measurement you prefer for each reading display Other fields on the Audio Analyzer panel allow you to choose coupling filter detector and level reference options Some of these options however apply only to the Function meters as you will see later in this chapter Loading the Audio Analyzer Figure 102 Loading the Audio Analyzer WA Instrument Audio Analyzer bl
17. Appendix E AP Waveform File Support MATLAB support 416 ATS 2 User s Manual Appendix F Test and Macro Translators The ATS control software includes the capability of translating tests cre ated in APWIN for System One System Two and System Two Cascade in struments into ATS test files The Test Translator description begins below Additionally AP Basic macros called procedures in APWIN documen tation can be translated from their original form into ATS macros See page 422 for a description of the Macro Translator Not all features on these other Audio Precision instruments exist in ATS 2 and some features common to all platforms are implemented differ ently in ATS 2 For these reasons some tests and macros although trans lated correctly and mapped to compatible functions will still need editing or reconfiguration to accomplish their original purpose NOTE Test files created in AP2700 for 2700 series instruments cannot be translated into ATS tests Check the Web The latest updates and hints for both the ATS 2 Test Translator and the Macro Translator are available at the Audio Precision Web site at ap com The Test Translator When preparings tests for translation on a System One System Two or System Two Cascade we strongly recommend that you upgrade to the lastest version of APWIN currently version 2 24 for test creation ATS 2 User s Manual 417 Appendix F Test and Macro Translators The Test Translator
18. See page 161 for illustrations and full descriptions of the FFT window ing functions available with ATS 2 Synchronous FFTs Another solution to the FFT looping discontinuity problem is to choose a signal frequency and FFT length such that an integer number of cycles of the signal will exactly fit the record length When this is accomplished the beginning and the end of the record will be at adjacent points in the signal and there will be no discontinuity This can only be done when you have precise control of the signal you are using for analysis and there are many circumstances when that is not possible But when synchronous FFTs can be used they bring this great ad vantage because the signal has not been modified by a window function it is unchanged Energy does not spread across the spectrum and tremen dous low level detail can be seen Look at the following four figures all FFTs of the same 800 Hz sinewave signal ATS 2 User s Manual 399 Appendix C FFTs Graphing FFTs NTUO 1 1 o o NTUO 1 i 1 1 500 1k 2k 5k 10k 20k 20 50 100 200 No Window nwa 1 1 1 i OAmnwa i 1 1 1 ES are fg kaa ail E 20 50 100 200 500 1k 2k 5k 10k 20k 20 50 100 200 500 1k 2k 5k 10k 20k Hann Synchronous Figure 295 FFTs of 800 Hz sinewave with
19. To load a waveform file and then output the waveform so that the em bedded audio tones are at the intended frequencies the DIO output sam ple rate OSR must be set to the same sample rate that was used in creating the file ATS offers two sampling rate options for loading an arbi trary waveform which are set on the Configuration panel at Utilities gt Configuration If the Set sample rate when loading generator waveforms checkbox on the Configuration panel is checked ATS will automatically set the DIO OSR to match the sample rate of the file being loaded If this checkbox is unchecked you must manually enter the sampling rate you de sire in the OSR field on the DIO panel If you enter a sampling rate different from the sampling rate at which the file was created the frequencies of the audio tones embedded in the out put signal will be shifted by the ratio of the two sampling rates The DSP processes in the multitone audio analyzer require that the multitone be precisely correct for synchronous operation If the tones have been frequency shifted the Multitone Analyzer FFTs will not be synchro nous and FFT windows will be necessary See Chapter 13 for more infor mation on multitone testing The Arbitrary Waveform generation memory buffers of the Analog Generator and Digital Generator are shared If both generators have Arb Wfm selected as the waveform the same waveform file will be used for both and the same signal will be prod
20. When Interpolate is selected the DSP compares the density of sweep points requested with the density of sample points available in the acquisi tion for the time span of the current sweep and graph If the requested points are much less dense than the acquisition points the DSP uses a bipolar peak sensing mode to eliminate potential graphic aliasing problems otherwise it interpolates See Graphic Aliasing on page 176 In the bipolar peak sensing mode the signal waveform is not faithfully represented but is replaced with an approximation indicating the positive and negative peak excursions of the signal If you use the graph Zoom and Zoomout commands the time span represented on the graph changes When Interpolate is selected Wave Display automatically switches between bipolar peak sensing mode and in terpolation mode for the best display The Interpolate selection produces a much more accurate display of the signal waveform than the Display Samples mode when the signal fre quency is high such as sample rate 100 or higher Display Samples When Display Samples is selected for each display point requested the DSP sends the amplitude of the nearest in time acquired sample to the computer for plotting Acquisition sample values may be repeated or dropped depending upon the relationship of acquisition sample density to display point density This mode is useful when examining the true quantization limited wave forms of very lo
21. Z pre ambles Block 192 frames Most of these alternative triggering sources will not cause any difference in the display of either spectrum analysis or waveform display of the jitter signal or of spectrum analysis of the interface signal waveform The differ ences will be seen only when displaying the interface signal waveform time domain with a narrow span a few microseconds between the Source 1 Start and Stop times so that the 3 UI 2 Ul and 1 UI pulse widths that make up the preamble can be distinguished On the various preamble trigger sources the trigger operation is such that the trailing edge of the first 3 Ul pulse of the preamble occurs nomi nally at time zero The first information displayed after time zero in these cases will be the remaining 5 Uls of the selected preamble followed by the first bit in the data area Depending on the nature of the interface signal ATS 2 User s Manual 209 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer panel settings 210 that could be the LSB of the audio signal if full 24 bit resolution audio is transmitted or the beginning of the 4 bit Auxiliary data area if audio is re stricted to 20 bits or fewer The transmit preamble selections have the same triggering characteris tics This triggering selection permits measurement of time delay through a digital device or system under test The Transmit and Receive Block selections cause signal to be acquired at
22. amp Fast RMS ANTE METERS CHANNEL B CHANNEL B a Detector Amplitude Selections Settings References 3 A i B CHANNELA CHANNEL A CHANNELA CHANNEL A CHANNEL B SaTALIK TOK Bale Pests Detectors CHANNEL B LEV andpass unction 1 Filter ios Ranging gt RMS Fast RMS gt BUYS Tuned to Ch ChB Level i FUNCTION y Narrow Ratio Detentors METERS Bandpass ChB Functi A E Fitter i Ranging P RMS Fast Rms gt ERE Tuned to ChA ChA Level amp Q Peak CHANNEL A XTALK TO B CHANNEL B CHANNEL B CHANNEL B CHANNEL B i Measurement Function CROSSTALK Audio Analyzer Panel Figure 111 Conceptual Block Diagram Audio Analyzer Crosstalk Function The Crosstalk function measures the leakage or crosstalk of a sinewave from one channel to the other A typical crosstalk test uses a ste reo stimulus with each channel driven with a sinewave of different fre quency For each analyzer channel a bandpass filter is steered to the frequency in the opposite channel The amplitude measured at this frequency is the ATS 2 User s Manual 133 Chapter 10 The Audio Analyzer The Function Meters 134 absolute crosstalk value The percentage of the opposite channel s signal amplitude as measured by the Level meter represented by the absolute crosstalk value of the channel under consideration is displayed in the chan nel s function meter For example consider a stimulus with a 1 kHz sinewave on Channel A and a 2 kHz sinewave on Channel B In the Audio A
23. 0 not indicated 1 unlocked sampling frequency 00 not indicated or see byte 4 10 48 kHz 01 44 1 kHz 11 32 kHz Channel mode 0000 not indicated default to 2 ch SCDSR single channel 0001 2 channel double sample rate 0010 1 channel monophonic 0011 primary secondary 0100 stereo 0101 reserved for user applications 0110 reserved for user applications 0111 SCDSR see byte 3 for ID 1000 SCDSR stereo left 1001 SCDSR stereo right 1111 Multichannel see byte 3 for 1D O E N user bit management 0000 no indication 0001 192 bit block as channel status 0010 As defined in AES18 0011 user defined 0100 As in IEC60958 3 consumer use of aux sample word 0000 not defined audio max 20 bits 0001 used for main audio max 24 bits 0010 used for coord audio max 20 bits 0011 user defined source word length if max 20 bits if max 24 bits not indicated not indicated 23 bits 19 bits 22 bits 18 bits 21 bits 17 bits 20 bits 16 bits 24 bits 20 bits ATS 2 User s Manual 389 Appendix B The Digital Audio Signal The Serial Digital Interface Signal Professional format channel status field interpretations Cont Bits iaei interpretation alignment level 00 not indicated 01 20 dB FS 10 18 06 dB FS channel identification if bit 31 0 then channel number is 1 plus the numeric value of bits 24 30 if bit 31 1 then bits 4 6 define a multichannel mode and bits 0 3 give the channel
24. 164 other windows The Flat Top window is the appropriate window for accu rate amplitude measurements such as when measuring individual harmon ics except when signals are so closely spaced that its selectivity becomes a problem Equiripple Window The Equiripple window developed at Audio Precision is an approxima tion to the Dolph Chebyshev window that has the narrowest main lobe width for a given maximum sidelobe depth The main lobe is approxi mately 12 bins wide that is the first null is about six bins from the main lobe center The first sidelobe which is also the highest is 147 dB from the main lobe The maximum amplitude error with a signal at the bin boundary is about 0 5 dB Hamming Window The Hamming window has the sharpest selectivity of all the windows provided Adjacent bins average about 7 dB and two bins away the re sponse is about 40 dB Amplitude error is about 1 7 dB for a signal at the extreme edge of a bin The sidelobes of the Hamming start at only 40 dB to 50 dB below the top of the main lobe about 4 bins away from the center bin The response fall off is not monotonic Gaussian Window The Gaussian window main lobe width is only slightly wider than the Blackman Harris window and the nearby rejection is considerably better than Blackman Harris reaching an average of 100 dB down in the fifth bin away from center The sidelobes are down more than 130 dB com pared to about 100 dB for Bl
25. 32000 Hz 44100 Hz 48000 Hz 65536 Hz 88200 Hz 96000 Hz 131072 Hz 176400 Hz 192000 Hz 262144 Hz Table 4 Sample rates for ATS s built in filters a The biquad keyword is followed by a colon and five floating point coefficients a av b4 bs and by in that order as described in the equation above 402 ATS 2 User s Manual MATLAB Downloadable Filter Support Appendix D User Downloadable Filters A valid sample file is shown here into 100 Hz Butterworta hnigna pass filter san let are OTO al eiac o SO a AO AO T A Ma bugquad LSO ES 0T OZ M 2 OOOO 12000000 1 O00 0 Co sample rate 4A000000 piguad ISS TOS O 9279792 OSO DOS 94 OSO ES piguad AS O ISS SUIS 2 OOOO OOOO OOOO As you can see a digital filter can be specified by 5 N 1 numbers where N is the number of second order sections User Downloadable Filters can be created by specialized third party soft ware such as MATLAB available from The Mathworks Inc See MATLAB Functions below for four MATLAB functions useful in working with downloadable filters and Audio Precision waveform files We also provide a filter creation program from Momentum Data Sys tems called Filter Design Package for Audio Precision FDP The software and documentation for FDP are available for download from our Web site at ap com MATLAB Downloadable Filter Support MATLAB is a technical computing environment used in DSP design and analysis MATLAB is a product of The Mathworks
26. 418 The ATS 2 translator can convert the test types listed in the following ta ble into ATS 2 tests instrument Testfile filename extension System Two System Two Cascade System Two Cascade tests can be imported directly into ATS System One and System Two tests must first be converted to Cascade tests as de scribed below System One DOS APWIN V 2 2x test file tst in S1 mode APWIN V 2 2x System One in S2 mode test file at1 System Two APWIN V 2 2x test file at2 in S2C mode System Two Cascade ATS Version 1 2 test file at2c ATS 2 test file ats2 Figure 296 Preparing a test file for translation from S1 EXE or APWIN to an ATS 2 compatible test file ATS 2 User s Manual The Test Translator Appendix F Test and Macro Translators Preparing S1 EXE and APWIN tests for translation To be compatible with the ATS 2 Test Translator S1 EXE and APWIN tests must be saved as System Two Cascade or Cascade Plus tests file name extension at2c Tests may be saved from any Cascade compati ble version of APWIN up through version 2 24 We strongly recommend that you upgrade to the lastest version of APWIN currently version 2 24 to prepare tests for translation Tests created in System One or System Two must be opened and re saved at the next instrument level in a step by step process until the test is saved as a Cascade test You cannot for example open a System One test and save it as a Cascade Te
27. Amplitude 50 00 mll a Frequency 1 00000 kHz The routing and configuration of the digital interface output signal are set in the Output section of the DIO panel Some settings which modify the embedded audio such as u Law and Pre emphasis show up in this area of the panel as well The controls in the bottom half of the panel enable you to impair the dig ital output in several ways An impaired digital interface signal can be use ful in testing proper operation of interface signal receivers 52 ATS 2 User s Manual The DIO Output Section Chapter 7 The Digital I O Panel Format Figure 16 The DIO Output Format Digital 1 0 Output Selections Fomat XLF y Sample rate L SR BNC Voltage 4Uptical Dual LA Resolution Qual LA 205 The first setting field is Format Select the serial digital interface output format and connector s from the list m XLR This is the balanced digital output The signal voltage maximum is 5 10 Vpp typical of the AES3 professional standard m BNC This is the unbalanced digital output The signal voltage maximum is 1 275 Vpp typical of the AES3id professional standard and twice the voltage of the IEC60958 3 consumer standard m Optical This is the Toslink output m Dual XLR These balanced digital outputs I and II are used in conjunction with each other as explained in the Dual Connector Mode sidebar below In this mode the Sample rate OSR field sets the overal
28. Cha dio Analuzer FFT Spectrum Analyzer INTERYO Digital Interface Analyzer FASTTEST Multitone Audio Analyzer Harmonic Distortion Analyzer A Range cd A To use the Audio Analyzer first open the Analyzer panel The Ana lyzer panel is a command selection on the Panel menu and is also avail TA able by the keyboard shortcut Ctrl Y or by clicking the Analyzer button on the Toolbar 124 ATS 2 User s Manual Signal Inputs Chapter 10 The Audio Analyzer Figure 103 Analyzer 15 x The Audio Analyzer panel Instrument Audio Analyzer ChA input Analog ChB Level Freq ES Range du OTAN Function La Measurement Function Amplitude y al Rangel gt Det E mes BP BR Fit Freg Mo E F References dBr A 387 3 re der B f287 3 re Freq 0000 kHz wiFS I O00 Y ufatts 8 000 Ohms dBm J600 0 Ohms The Audio Analyzer is loaded in the Analyzer panel as the default in strument If another Analyzer instrument is loaded drop down the list and choose Audio Analyzer Signal Inputs e Analyzer Figure 104 EE Audio Analyzer panel inputs Instrument Audio Analyzer Ch A Input Digital a Ch B aa AR Range a a The Input field of the Audio Analyzer offers two signal input selec tions Digital and Analog These choices access signals from the Digital Input Output DIO panel or the Analog Input panel respectively Digital signals are sent directly to th
29. F9 or Go is initiated regardless of signal amplitude Auto The ChA Auto and ChB Auto selections will cause triggering at one half the peak to peak value if the selected channel has a signal ampli tude greater than digital infinity zero Fixed Sensitivity ChA Fixed Sens and ChB Fixed Sens use the value set in the Sens sensitivity field as the triggering threshold The Sens field appears only when one of these two selections is made An FFT acquisition will trigger on the first zero crossing of the selected slope positive or negative set with the adjacent option buttons that oc curs after the signal amplitude is sufficient to swing both through zero and the Sens value If the signal contains a sufficient DC offset such that it does not swing through zero no triggering will take place In this case use one of the quasi AC coupling modes Subtract Avg or Sub 1 2 pk pk that will 178 ATS 2 User s Manual Triggering Chapter 11 The Spectrum Analyzer cause the processed signal to pass through zero and permit triggering to function Trig In Ext The Trig In Ext selection refers to the TRIG IN BNC connector on the rear of the ATS 2 chassis The trigger circuitry is edge sensitive and an FFT acquisition will trigger on a positive going or negative going edge on the signal at this connector depending upon the setting of the trigger Slope buttons Digital Gen If the Digital Generator is outputting a Noise waveform a
30. Figure 185 Typical Multitone Distortion measurement Figure 186 Example of a ee multitone noise response graph Fi F2 F3 F4 F5 F6 F7 F8 In many devices noise is not constant but varies according to the ap plied signal Multitone is the only technique that can measure noise in the presence of signal To measure noise without measuring the applied signal the Multitone FFT Length must be set to twice the length of the stimulus waveform In the ATS Multitone Audio Analyzer this is accomplished when the FFT Length is set to Auto Under such conditions the analyzer frequency resolution is twice the res olution of the generated signal with twice the bins of an FFT that matches the waveform length The power in these extra bins is a measurement of the noise generated in the DUT in the presence of applied signal exclud ing the signal itself See the sidebar for more detail 222 ATS 2 User s Manual Multitone Measurements Chapter 13 The Multitone Audio Analyzer Odd bins only In multitone tests the length of the waveform and the length of the transform buffer are normally set to be the same in our example 8192 samples giving a frequency resolution or bin width of about 5 86 Hz at a sample rate of 48 kHz For a measurement of noise in the presence of signal the length of the transform buffer is set to be exactly twice the length of the multitone waveform Under these conditions the FFT is still synchronous but at
31. Hamming Gaussian Rife Vincent 4 and 5 Equiripple shown for comparison Hann Window The Hann window is a raised cosine window named after its inventor Austrian meteorologist Julius von Hann It provides good selectivity near the top of the main lobe about 6 dB one bin away from center and about 30 dB two bins away with no sidelobes Its skirts more than 3 bins off center are not as steep as the Blackman Harris window The Hann window causes approximately 1 5 dB maximum amplitude error due to window attenuation if the signal is at the extreme edge of the bin Blackman Harris Window The Blackman Harris 4 term minimum sidelobe window was developed by R B Blackman and E J Harris Compared to the Hann window it is not quite as selective across the central several bins about 3 dB in the ad jacent bins and about 14 dB two bins off but has steeper skirts beyond that point The Blackman Harris window has sidelobes below 92 dB re sponse fall off is not monotonic It has a reasonably flat top with a maxi mum amplitude error of about 0 8 dB if the signal is at the extreme edge of the bin Flat Top Window The Flat Top window is designed for the greatest amplitude measure ment accuracy It provides a maximum amplitude error due to window at tenuation of less than 0 02 dB However its selectivity is poorer than the ATS 2 User s Manual 165 Chapter 11 The Spectrum Analyzer Spectrum Analyzer Window Selection
32. If there is more than one data column you must indicate the column you would like to use as limit data for your sweep Using the Attached File Editor Once a file is attached you have the opportunity to edit the data in the file Click on the Edit Upper Limit or Edit Lower Limit button to edit the attached file The Attached File Editor will open Figure 244 The Attached FRET M RIN ge ae Vee ae coal File editor Digital Generator Data 141 lowerlimit A alvzer Level A 20 0014 Hz 10 000 dBu 10 000 dBu 199 990 Hz 10 000 dBu 10 000 dBu 200 000 Hz 7 000 dBu 7 000 dBu 1 99990 kHz 7 000 dBu 7 000 dBu 2 00000 KHz 13 000 dBu 13 000 dBu 20 0000 KHz 13 000 dBu 13 000 dBu The Attached File Editor is very similar in appearance to the Data Editor page 307 but the two windows have different functions The Data Editor displays the data in memory while the Attached File Editor displays the data in the upper or lower attached file The Attached File Editor is also available from the Table Sweep dialog box see page 270 and the EQ Curve dialog box see page 87 ATS 2 User s Manual 313 Chapter 18 Editing Data and Setting Limits Setting Limits 314 You can view and edit the attached limit data in the Attached File Edi tor In the Attached File Editor display the column corresponding to the limit data you have selected is marked with two asterisks Changes you make in the attached file values will not be
33. Inc who can be reached at 508 647 7000 or on the Web at http www mathworks com Two MATLAB functions useful in creating and modifying downloadable filters for use with ATS 2 have been provided as an aid to our customers who also use MATLAB ap write filter generates filter files from within MATLAB and ap read filter imports such files into MATLAB for further manipulation These functions are provided as MATLAB files filename extension m on the Audio Precision Resources Disc and are also available on our Web site at ap com ATS 2 User s Manual Appendix D User Downloadable Filters MATLAB Downloadable Filter Support ap_write_filter Syntax ao Wiel eS a Eee elo Wied den Meer ellos Wis thicic fae Il c i eyo mice ea Meer elo Wied tee efe an e ie hdl ele elo Wrenn de cen ao ieee e PiLenance tute pe Anke some leprae ces Pile nanicy hi Leen Neyee dire some le rele o el Atenas tree Eype ros alo Vert are ay Oy enano n T iltrer pe Laro Semele trees e ena dle e pe aos emplee Ss PO t i been ie pe pile cali le cate 0 2 o ter e pe ihe sem le ewe 7 10 13 AO leer pe Jane sample are 40 e al Description ap write filter generates a text file in the format recognized by the downloadable filters feature of ATS Filters in any of the standard MATLAB forms second order section transfer function zero pole gain and state space can be written to the file along with the s
34. THD N Amplitude Function The THD N Ampl amplitude function expresses the amplitude of the distortion products and noise in absolute units independent of the am plitude of the fundamental signal Although the previous function THD N Ratio is used much more commonly THD N Ampl is particu larly useful when performing amplitude sweeps of audio devices since it helps make clear that the noise component is at a constant amplitude and is unrelated to the signal amplitude When using the THD N Ampl function the list of units and their refer ences for both analog and digital signals are the same as described above in the Level Meter Units topic on page 126 Bandpass Function The Bandpass function is a selective voltmeter a function sometimes called a wave analyzer implemented by DSP techniques Each channel in cludes a narrow bandpass filter of approximately 1 13 octave Q 19 3 dB bandwidth approximately 5 2 of center frequency The bandpass filter center frequency may be fixed or may track one of several parame ters See BP BR Filter Tuning on page 149 Figure 113 shows a conceptual block diagram of the Audio Analyzer with the Bandpass function selected ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer CHANNEL A PEAK 1 442 Vp METERS eo es we 1 1 E op CHANNEL B k n CHANNEL A CHANNEL A CHANNEL A CHANNEL A Digital Analog Analog AES A to D Peak i
35. The jitter sinewave generator can be equalized in the same way that the ATS 2 signal generators can Click the EQ Curve button to select an EQ file to attach to the jitter generator See Specifying the EQ Curve on page 88 for general infor mation on using EQ files with generated signals The DIO Input Section Figure 24 The DIO El Input Section Input Format KLF bal Zlm 110 hms Sample rate1SP EE Connector Voltage EES C Connector Il Resolution 24 Bits De emphasis or a Scale Freg by Meas Input Rate a Rate Fef 48 0000 kHz Peak Monitors Channel A Mode Channel B o l ra z0 16 lz a d F By B C Data Bits Error Flags ChA ChE confidence lock coding party invalid invalid Jitter Measurement Jitter EE cue s ae Status Bits Bw 700Hz to 100kHz C Pki Avg The routing and configuration of the digital interface input signal are set in the Input section of the DIO panel At the top area of the panel meters display the measured input sample rate ISR and the interface bitstream voltage level Some settings which af fect the reception of the embedded audio such as Resolution and De emphasis show up in this area of the panel as well The middle area of the panel contains data monitors embedded audio peak level meters and interface error flag indicators 60 ATS 2 User s Manual The DIO Input Section Chapter 7 The Digital I O Panel At the bottom of the panel a
36. Trigger Delay Time Figure 145 ATS Trigger Delay and Slope M8gel selections Delay 0 00000000s Source Free Aun Slope Pos Neg If a negative value was entered in the trigger Delay field before Sweep Start was pressed the portion of the record selected for transform by the FFT Start Time field can extend back into the pre trigger portion of the record by entering a negative value in the FFT Start Time field The Spectrum Analyzer instrument has the ability to fill the acquisi tion buffer with signal samples beginning at the moment of the triggering event or starting at a defined time before or after the trigger occurs This time is set in the trigger Delay field This enables analysis of signal conditions both before and after the trig gering event A negative value entered in the Delay field determines the length of time prior to the trigger event signal that samples are retained The total length of signal acquired will be as defined in the Length field with the re mainder of the acquisition buffer filled after the trigger For example with the Acquire set to 24k the length of the acquisition buffer for each channel is 512 ms at a 48 kHz sample rate If the trigger De lay time value is 50 ms then 462 additional milliseconds of signal follow ing the trigger will also be acquired to fill the entire 512 ms buffer Trigger Slope See Figure 145 To the right of the trigger Source field are the trigger Slop
37. at the rate of 3 dB per octave Arbitrary Waveforms 2 Digi iol Figure 91 Loading an 2 Digital Generator lol x j Ab WE arbitrary waveform E MA Waveform J Ca LM Look in a WAVEFORM 5 AE ooo n El al ex E El 32K a 1K 0 44 agm a 40010048 agm ss 400 2048 44K 1K 0 48 agm la 40011044 agm a 400 3 44 48K laa 2K_fm60 agm sa 40011048 agm a 400 3 48 ffs 1415tt44 agm a 400 0 44agm a 40012044 agm fa 400 4044 Dith ls 192044 agm s 400 0 48 3gm a 40012048 agm a 400 4048 laa 1920tt48 agm 8 40010044 agm a 400 2044 agm a 400 6044 Y la 2 Filename fragm ass OOO Files of type Waveform Files agm ags y Cancel Z The generator arbitrary waveform function allows you to load a prop erly formatted digital waveform file into the ATS 2 DSP and route the waveform to the Digital Generator outputs Arbitrary waveforms files provided with ATS 2 include single tones tone combinations for IMD testing multitone waveforms and calibration tones and other useful waveforms Waveform files must be of the Audio Precision agm Generator Mono or ags Generator Stereo file types You may also make custom arbitrary waveform files using a file creation utility provided with ATS 2 or with third party applications such as MATLAB See Multitone Creation on page 236 ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator
38. rear panel connectors 34 Monitoring Digital Interface Analyzer 212 Monotonicity waveform 117 Move to bin center FFT window 165 Multitone analysis 218 informing analyzer about waveform 216 invalid readings 233 minimum multitone duration 232 waveform requrements 215 436 Multitone Audio Analyzer capabilities 214 Introducti0N 213 processing 228 rss Summing resolution 227 setting record length 227 setting the generator 216 trigger AelaV 230 triggering modes 229 triggering resolution 226 Multitone Creation Utility 236 369 Normal Normal Regulation algorithms 357 Nested sweeps 269 Noise in the presence of signal 222 Noise waveforms 90 113 None move to bin center FFT Window 165 Normalize Compute algorithm 319 Notch filter see bandpass bandreject filter O Object linking and embedding 351 Offset Sine waveform 111 ULE lt cesaron ras oe 51 Operation Regulation setting 357 Optimize graph 4 ui mars ees 288 Oscilloscope view see Spectrum Analyzer e AE A 54 Output Sample Rate see OSR Outputs ON OFF Analog Generator 79 Digital Generator 101 Outputs monitor hs esc
39. 000 ee eee eee ee eee 344 Input Frequency 0 00 eee ee 344 Out of Range Indicator 345 TRIGIN oso eee a a a a SES 345 TRIG OUT and the Main Trigger Panel 345 Auxiliary Control Output andiInput 348 Chapter 23 Automating Tests 351 Introduction 3 uke eeeee bee ened a a a a a a a 351 Learn Mode 000 eee ee ee ee 351 The Macro Editor 2 2 005804 352 AP Basic Documentation 353 Chapter 24 Regulation 22000052 ee 355 Examples of Regulated Sweeps 359 Chapter 25 Configuration and the Utilities Menu 361 The Configuration panel 361 ATS 2 User s Manual Od Bag eee eee eee eee eee eee es 364 The LogFile 0 00 eee eee 364 o 6 sea e whee eee he wee ee eee ewe ee eee 366 Restoring the ATS 2 Hardware 367 Hardware Status 0 0000 eee ea 368 Turn All Outputs OFF ON 2 00 368 ClearLogFile 0 0000 eee ee a 368 ViewLogFile 0 2 0 00 ee eens 368 Learn Mode 0 00 eee eee ee ee 369 Multitone Creation 0 005002 369 Appendix A Units of Measurement 371 Introduction 0000 eee a ee 371 Analog Amplitude Units 372 Digital Amplitude Units 376
40. 0002 ee eee 304 Using a Bar Graph for Readings 305 Using a Bar Graph for Settin9S 306 Chapter 18 Editing Data and Setting Limits 307 The Data Editor o 307 The Data Editor Panel 308 COIUNINS o sirios raras 308 ROWS a a a ee ee 308 Data aaa aaa a a a a a a a a a a a 308 Editing the Current Data in Memory 309 Saving ATS Data lt 4 8 6 4465 e464 OH sae 310 Setting Limits 2 00000 bas 310 Making a Limit File 311 Attaching a Limit File 312 Using the Attached File Editor 313 Actions Upon Failure 314 More About Using AP DataFiles 314 Chapter 19 Performing Computations on Data 317 The Compute Dialog Boxes 20 318 Compute Normalize 2 2 200 319 Compute Invert 2 0050 eee eee 320 Compute Smooth 2 0050 ee eee 320 Compute Linearity 2 200 321 Compute Center 0000 ce eee 322 Compute Delta 2 ccen845 86456 6e beh B ESE HEE EK 323 Compute Average 2 0000 eee 324 Compute Minimum 208 325 Compute Maximum 2 020800 325 Compute Equalize 2 2 005 eee 326 Compute Status 0000 bee eee
41. 189 Example of multitone z crosstalk response graphs Fi F2 F3 F4 F5 F6 F7 F8 F9 F140 F11 F42 CHANNEL B D Fl F2 F3 F4 F5 F6 F7 F8 F9 F10 F41 F12 Crosstalk depends on the presence of at least two unique tones in each channel tones that are not present in the multitone waveform for the oppo site channel In our example F9 and F11 exist only on the A channel and F10 and F12 exist only on B To measure crosstalk from B to A the Multitone Ana lyzer rejects all bins but the ones at F10 and F12 In the same way crosstalk from A to B is measured by rejecting all bins but the ones at F9 and F11 The only signal in these bins will be crosstalk from the opposite channel A response curve the dark lines are drawn through these ampli tudes on each channel for display To characterize crosstalk across a range of frequencies use multitone waveforms with a range of unique crosstalk tones The ATS Crosstalk Multitone Measurement automatically determines from the two generator waveform buffers which frequencies are unique to each channel Then Crosstalk measures the amplitude on the opposite non driven channel at each of those unique tones providing crosstalk re sponse curves as shown in Figure 190 ATS 2 User s Manual 225 Chapter 13 The Multitone Audio Analyzer Frequency Resolution 226 ANN ERA 200 Suu Hz Figure 190 Typical Multitone Crosstalk measurement Time Domain View A time dom
42. 326 Clear AllandReset o 327 Comparing Results with Original Data 327 Chapter 20 Printing and Exporting 329 Printing ATS Graphs 2 0050002 329 Page Setup na c bh dD GEEK EOE ER ERR ERE ESS 330 Print Setup 0 00 eee ee ee eee 331 ATS 2 User s Manual xiii XiV Printing a Graph wa cecaee deuewn te Bees hed eee 331 Print Preview a a 2 000 2 ee a a 332 Printing ATS Data as a Table 332 Printing toaFile 0 000 eee eee 333 ExportingaGraph 0 20005 eee 334 Copying a Graph to the Clipboard 334 Copying a Window or Screen to the Clipboard 334 Chapter 21 MONITO 337 Headphone Speaker Monitoring 337 The Volume Bar 000 eee eee ne 337 Headphone Speaker panel 2 4 338 The Monitor Outoputs 2 02008 339 The SOURCE Outputs 2 500002 340 The FUNCTION Outputs 2 204 340 Chapter 22 Sync Ref Trigger and Aux 341 SYNC REF IN a eee ee ee eee ee 341 Sync Ref Input Panel 2 2 2 2 200 342 Reference Input Source 2 284 342 Squarewave frequency ranging 343 Frame Lock 0000 eee ee eee eee 344 Input Termination Impedance 344 Frequency 2
43. Audio Analyzer is a DSP instrument selection on the Analyzer panel It is one of the key audio analysis tools available in ATS The Au dio Analyzer can measure audio level frequency noise THD N crosstalk phase and more with a wide selection of filters and detector char acteristics For many measurements the Audio Analyzer is the only in strument you will need POE E SE SE SE E E E E a a a PEAK e a METERS s es es we ew Hg CHANNEL B E i z a CHANNEL A CHANNEL A CHANNEL A CHANNEL A ye S Analog Analog Receiver fe Renee Ranging HH AC DC ia r Input Coupling i CHANNEL B CHANNEL B CHANNEL B CHANNEL B a Inputs E Analog Input Panel E A O AAA OS Frequency References CHANNEL A Digital CHANNEL A AC DC FREQUENCY Coupling INEM METERS CHANNEL B CHANNELA CHANNELA Detectors CHANNEL A evel m gt amp Fast eich METERS CHANNEL B CHANNEL B CHANNEL B Ea Amplitude Ea References CHANNELA CHANNELA Detectors CHANNELA gt Ranging gt RMS Fast RMS gt amp Q Peak FUNCTION i METERS Var 1 abl e Detectors Measurement Function P Ranging P gt rws Fast Rus gt MER amp Q Peak CHANNEL B CHANNEL B CHANNEL B Audio Analyzer Panel Figure 1 01 Conceptual Block Diagram Audio Analyzer
44. Auxiliary e Show Readings Show Settings Figure 218 Source 1 Instrument Browser in External Sweep mode To enable the External Sweep mode choose an instrument reading in stead of a setting for the independent variable in the Source 1 browser When this is done the controls available in the Source 1 section of the Sweep panel will change to External Sweep controls The Steps Stepsize Multiply and Table Sweep controls disappear and Spacing End On Min Lvl and the Min Lvl I D fields appear in their place as shown in Figure 219 For a frequency sweep the Source 1 instrument reading will be an Ana lyzer frequency meter for amplitude controlled sweeps a level or ampli tude reading is normally used Before acquisition the reading must also satisfy the requirements entered in the Settling panel for that instrument See Sweep Settling page 278 272 ATS 2 User s Manual External Sweeps Chapter 15 Sweeps and Sweep Settling Figure 219 Source 1 External Sweep Controls Data 1 Analyzer Level A El Top J16 00 Y Autoscale Bottom 1 000 ri f Logt Lin oies paie Lirnits Data z None ES Top A JS Autuscale Bottom bs Dive FS Suto linte SOUE 1 fAnalyzer FrequencyA Start 20 0000 kHz Stop 20 0000 Hz Divs r Eto End On 1 00000 kHz Spacing 5 00000 A Min Lvi 1 000 mi Analyzer Level A El Repeat Stereo Sweep 3 Go Append Single Point Start and Stop In an
45. B A to D Converters CHANNEL B taun A A nnn nunn n nnnm mmEmEmEmMmEMEmMEmMmMEmMEmMEmNEENEE llo y Frequency References CHANNEL A CHANNEL A Digital ACDC FREQUENCY Coupling TT METERS CHANNEL B CHANNEL A CHANNEL A ee CHANNEL A 1 005 V 005 V LEVEL En a 3 METERS a B am B Detector Amplitude Settings References CHANNEL A AC FUNCTION Coupling 0 8 deg METER Phase Comparator 7 AC PHASE DISPLAY Coupling SETTING a CHANNEL B Measurement Function PHASE Audio Analyzer Panel Toma A EA IR E A A E A E Aa a AO la a a A Figure 115 Conceptual Block Diagram Phase Function When using Phase the right hand Function meter display becomes a setting field with a list of four options Auto 180 180 deg 0 360 deg and 90 270 deg In Auto ATS reads absolute phase error Delays in the DUT can cause signals to lag or lead by many waveform cycles and for swept measure ments Auto will correctly show and plot readings well beyond 360 de grees When viewing phase error in Auto without sweeping the reading is reset at each waveform cycle and the phase error will always be displayed as less than 360 degrees The 180 180 deg 0 360 deg and 90 270 deg choices ex press the phase error in windows of 360 with the window for each se lection placed along a scale at a different positions in relation to 0 See Figure 116 The BW high
46. Connector II selections have no effect on the selection of the embedded audio In dual connector mode the selected Analyzer instrument Audio Analyzer ATS 2 User s Manual The DIO Input Section Chapter 7 The Digital I O Panel Spectrum Analyzer Multitone Audio Analyzer or Harmonic Dis tortion Analyzer always analyzes left channel audio from Connector I and right channel audio from Connector II See Chapter 12 The Digital Interface Analyzer Input Sample Rate ISR Figure 27 The DIO Sample rate ISR and 6 ample Pate SA 45 0000 kHz Voltage selections voltage 14 470 vop The Sample rate ISR field labeled Rate on the small form of the DIO panel displays the measured input sample rate or ISR at the Connec tor I digital input In dual connector mode the ISR displays the sample rate of either the Connector I or Connector II inputs as selected Input sample rates from 28 8 kHz to 108 kHz are accepted A drop down list al lows you to specify the units of measurement for the ISR The input sample rate displayed here the ISR is also available as an embedded frequency scaling factor selection in the Scale Freq by field in both the Output and Input sections of the DIO panel where it is called the Meas Input Rate The input sample rate may be used to control a sweep as part of a test by selecting Dio as the instrument and selecting the reading Input Sam ple Rate at Source 1 or Source 2 on the Sweep panel Voltage S
47. Data None If this box is checked no sweep point values will be written to the log file All If this box is checked all sweep point values will be written to the log file Failed Only If this box is checked only those sweep point values that have failed the limits will be written to the log file ATS 2 User s Manual 365 Chapter 25 Configuration and the Utilities Menu The Configuration panel Graph Figure 282 The Graph ATS Ari Configuration tab The Graph configuration page enables you to set the Graph color assign ment and copy options for ATS See Trace Colors on page 298 Copying a Graph to the Clipboard on page 334 and Bitmaps and Vector Graphics page 335 The Graph Trace Colors options are On Sweep e Reset color cycle If Reset color cycle is checked each new sweep will reset the color cycle so that the first trace of the sweep is cyan If the Reset color cycle is unchecked new sweeps will use the color cycle If you manually change any color to Data assignment ATS will maintain your new color assignments throughout subsequent sweeps e Use test colors only When you are appending current sweeps to a test file loaded from disk using the Append checkbox on the Sweep panel and Use test colors only is checked the newly appended sweeps will maintain the colors used in the file you have loaded If Use test colors only is unchecked any newly appended sweeps will move through the color cycle 366 ATS 2 U
48. Data Editor and on the Graph panel Regulation failures are marked with a white R at the top of the graph above the plotted point See Regulation page 355 Trace Colors ATS traces are normally displayed in one of six colors m cyan m green m yellow m red m magenta and m blue These colors can be automatically assigned by ATS according to the type of sweep and the settings made on the Configuration panel The or der of these colors is called the color cycle and when ATS automatically increments colors it always does so following this order The cycle wraps back from blue to cyan when the end of the cycle is reached The color gray is also available and can be manually assigned to any trace However gray is not part of the color cycle and is normally reserved as the color for reference traces recalled from the Graph Buffer ATS 2 User s Manual Trace Colors Chapter 16 Graphs Color Assignment for a New Test When a single sweep is made in a new test ATS normally chooses cyan as the color for the trace However if you have assigned a different color to a trace and subsequently run a new test without closing ATS the color you have previously chosen will be the trace color for the new test Color Assignment for Multiple Data Set Sweeps In a single sweep with more than one set of Data values being plotted by default ATS assigns the Data traces colors according to this pattern If the Reset color
49. Delay Algorithm Analyzer Level 4 1 00000 1 000 w Bo 30 00 me Fiat Analyzer Level B i 0000 lt fi O00 q Bo 30 00 me Fiat Analyzer Frequency 4 Jo s0000 10 0000 mhz i 2 000 ms Fiat Analyzer Frequency B o 50000 10 0000 mHz ho 2 000 ms Fiat Analyzer Amplitude A 1 00000 la 30 00 ms Fiat Analyzer Amplitude E 1 00000 2 la 30 00 ms Fiat Analyzer a pos E Sample Rate 0 50000 2 100 000 mHz a la Voltage 3 00000 10 00 m pp e fa Jitter Amplitude 2 00000 3 000 ns ffe 100 0 ms Exponential E Dey 0 20000 0 00050vdc f3 2000 me Flat Digital In o 00000 fo dee mffe eooo ms ffe Figure 221 The sweep Settling panel The ATS Settling panel is available by selecting Panels gt Settling from the Menu bar or by clicking the Settling button on the toolbar you can also launch the Settling panel by selecting Sweep gt Show Settling Panel from the Menu bar The Settling panel allows you to set a number of settling parameters for each of the meters available in an ATS sweep The Analyzer meters avail able on the Settling panel will change with the Analyzer instrument you have selected ATS 2 User s Manual 279 Chapter 15 Sweeps and Sweep Settling Sweep Settling 280 Settling Concepts Since much of the signal disruption occurs at the beginning of a sweep step because of instrument and DUT stabilization the ATS settling function first ignores
50. Digital Data Units 378 RAUOUNNS sade eke eee dw ew eee baw ec ee we RE SSS 378 Relative Units 2 00 eee ee a 378 Frequency Units 0 00500 eee eee 379 Phase UN 380 Time Units 380 DCX 127 Units 0 a a a a eee 381 DCX 127 Amplitude Units 381 DCX 127 Resistance Units 381 DCX 127 Digital Inout and Output Units 381 Appendix B The Digital Audio Signal 383 The Serial Digital Interface Signal 384 Bi phase Mark Encoding 385 The Frame and Subframe 385 Channel Status o 386 Serial Interface Measurements 391 Appendix C A 393 The Fast Fourier Transform 393 Real Time vs Batch Mode 393 Acquiring Data o 394 The FFT Record 00 00 2 ee eee ee ne 394 FFT Bandwidth 00050 eee eee 394 FFT Bin Width 20000 eee eee 395 FFT Record Looping 2 20005 eee 396 ATS 2 User s Manual XV FFTWindowing 00 ee eee eee 397 Synchronous FFTS lt 4 e544 edad dae hh GREE RD x 399 Graphing FFTS 002 ee eee eee 400 Appendix D User Downloadable Filters 401 Creating User Downloadable Filters 401 User Downloadable Filter Design Constraints 401 MATLAB Downloadable
51. Digital Gen trigger occurs once per cycle of the noise sequence If the Digital Generator is outputting an Arbitrary Waveform a Digital Gen trigger occurs at the first sample of the waveform For all other waveforms a Digital Gen trigger occurs at each cycle of the waveform Analog Gen If the Analog Generator is outputting a Noise waveform an Analog Gen trigger occurs once per cycle of the noise sequence If the Analog Generator is outputting an Arbitrary Waveform an Ana log Gen trigger occurs at the first sample of the waveform For all other waveforms an Analog Gen trigger occurs at each cycle of the waveform Line Mains The Line Mains provides a trigger at each cycle of the AC waveform of the mains line powering ATS 2 Jitter Gen The Jitter Gen selection provides a trigger at each cycle of the wave form selected in the Jitter Generation section on the DIO panel This provides stable viewing of the jitter waveform generated by ATS 2 Fixed Level The ChA Fixed Lev and ChB Fixed Lev fields operate identically to conventional oscilloscope triggering ATS 2 User s Manual 179 Chapter 11 The Spectrum Analyzer Triggering 180 When either of these trigger selections is chosen a level Lev setting field is displayed Positive or negative values may be entered into this field An acquisition will be triggered the first time the signal with the specified slope positive or negative passes through this level
52. Digital signals are applied directly to the Multitone Audio Analyzer DSP analog signals are first digitized by precision ADCs selected on the Analog Input panel before being applied to the Multitone Audio Ana lyzer To configure analog input connectors range coupling select ADCs bandwidth etc go to the Analog Input panel see Chapter 6 To config ure digital input connectors digital input format and other aspects of inter face go to the DIO panel see Chapter 7 ATS 2 User s Manual 217 Chapter 13 The Multitone Audio Analyzer Peak Level Monitors 218 Peak Level Monitors e Analyzer Mel Instrument FASTTEST Multitone Audio Anal Ch A Input Digital a Ch B 7 Peak mon MEAN gt SAA i Spectrum D000 dEFS Jo 00000 a a The two Peak Mon meters on the Multitone panel continuously display the peak amplitude of the digital signal as it is presented to the Multitone Audio Analyzer Only digital domain units FFS dBFS FS or bits are available for these meters Figure 177 Multitone Audio Analyzer Peak Level Monitors The primary purpose of the peak monitors is to avoid overload of the in put analog to digital converters ADCs When signal is being acquired from the analog source and Auto Range is in use on the Analog Input panel ADC over range should never be a problem If any of the Analog In put range controls is fixed you must verify that the maximum signal ampli tude never exceeds
53. External Sweep the extent and direction of the sweep is not under ATS s control You must inform the Sweep panel of the range in which you expect the signal and the direction you expect it to move This allows ATS to track the signal for proper plotting on the graph Enter the expected values in the Start and Stop fields If the value of Start is less than Stop ATS will expect that the sweep will proceed up ward in the direction of lesser to greater If Start is greater than Stop ATS assumes that the sweep will proceed downward If the sweep actually moves in the direction opposite to that indicated by the Start and Stop field values ATS cannot plot a meaningful graph The Start and Stop values and associated units also set the graph scales and calibration and the field values provide references for other Ex ternal Sweep controls such as End On Spacing The Spacing field helps to determine the step size within the sweep Spacing is entered as a percentage and the range for each new data point is the value of the last point plotted plus or minus the Spacing per centage At the beginning of a sweep the Start On rules below deter mine whether or not Spacing affects the acquisition of the first plotted point ATS 2 User s Manual 273 Chapter 15 Sweeps and Sweep Settling External Sweeps 274 End On The End On field in the Source 1 section of the Sweep panel allows you to set the conditions under which an External Sweep
54. Filter Support 403 ap write filter cajones bear ero bee 404 Syntax aaa a a a a a a a a a a a a a a a 404 Description a a a a a a a a a a eee a eee 404 Multiple Sample Rates 405 Filter Restrictions 405 Examples o ooa aaa a a 000 eee a a a a a 405 ap read filter aoaaa 406 Se IE 406 Description aoaaa a a a a a a a a a a a a a a a ews 406 SA 407 Appendix E AP Waveform File Support 409 Exporting to WAV 409 Operation 409 Tips and Tricks 0000 ee eee 410 Importing from WAV 411 Operation 0 000 eee ee ee ee 411 MATLAB support 000 ee eee ee 412 ap write wave a a a a 412 Syntax oaa a a a a a a a a a a a a a 412 Description oaoa a a a a a a a a a a a 412 Example 000 eee ee a a a a a 413 ap read wave ouaaa a 414 Syntax aaa a a a a a a a a a a a a a a a a 414 Description oaoa a a a a a a a a a a a a 414 Example o oo aaa a a a a eee a a a a a 415 Appendix F Test and Macro Translators 417 Check the Web 00002 a a a 417 The Test Translator 0 02 002 ee eee 417 Preparing S1 EXE and APWIN tests for translation 419 Macros for batch converting APWIN tests 419 Using the ATS 2 Test Translator 420 How the Test Translator Makes Decisions 421 X
55. Harris window provides a good trade off between a window s ability to separate closely spaced spectral peaks and its ability to discriminate between moderately spaced spectral peaks that are quite different in amplitude Depending on whether or not the tone being measured is centered in the bin there can be as much as 0 8 dB of error in the amplitude measurement Hann The Hann window provides good selectivity near the top of the main lobe about 6 dB one bin away from center and about 30 dB two bins away with no sidelobes Its skirts more than 3 bins off center are not as steep as the Blackman Harris window The Hann ATS 2 User s Manual 207 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer panel settings window causes approximately 1 5 dB maximum amplitude error due to window attenuation if the signal is at the extreme edge of the bin a Flat Top The Flat Top window provides measurements accurate to a few hundredths of a decibel for any spectral peak but sacrifices selectivity for closely spaced tones m Equiripple The Equiripple window has the narrowest main lobe width for a given maximum sidelobe depth The main lobe is approximately 12 bins wide that is the first null is about six bins from the main lobe center The first sidelobe which is also the highest is 147 dB from the main lobe The maximum amplitude error with a signal at the bin boundary is about 0 5 dB None The None selection so
56. Interface Analyzer can invert the pulse width histogram de scribed above to obtain a bit rate histogram The time between each suc cessive pair of zero crossings of the interface signal is measured and these times are sorted into bins depending upon their value Figure 159 shows three spikes corresponding to the frequency equiva lents of the 3 UI 2 UI and 1 UI pulses that make up the signal At a 48 kHz sample rate the 3 UI pulses are equivalent to a frequency of about 2 07 MHz the 2 UI pulses correspond to a frequency of about 3 10 MHz and the 1 UI pulses are equivalent to a frequency of about 6 16 MHz Jitter will spread each spike across the nearby spectrum e Audio Precision 1000k 4000k FOO Figure 159 Digital Interface Analyzer interface rate probability 48 kHz rate ATS 2 User s Manual 199 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Histograms As indicated in Figure 151 this view requires these Sweep settings Source 1 Intervu Amplitude and m Data 1 Intervu Probability Source 1 Stop should be set to about 7 MHz a Data 1 range of 0 to about 100 on a linear scale is useful for this view Jitter Histogram The jitter histogram view displays the probability distribution of the am plitude of the jitter signal The width of the histogram represents the peak to peak jitter amplitude The breadth of the display near its mid section is indicative of the average jitter ampli
57. Mode An AP Basic macro will open in the Macro Edi tor and each ATS keystroke and mouse click will be entered into the Macro Editor as a line of AP Basic code as you set up and run a test On the Macro and Utilities menus a checkmark will remain next to the Learn Mode choice while ATS is in Learn Mode and the shape of the mouse pointer will change to that of an audio cassette indicating that a re cording is being made To prevent a particular mouse click from being en tered into the macro press and hold the keystroke combination Ctrl Shift while clicking This temporarily suspends Learn Mode To exit Learn Mode click the Stop Learn Mode button on the Learn Mode toolbar or from the Main menu choose Macro gt V Learn Mode or Utilities gt y Learn Mode The mouse pointer will return to its nor mal shape the checkmark next to the Learn Mode menu choice will dis appear and you will be prompted to save the macro The Macro Editor if Macro macro ATS Basic Macro design File Edit View Macro Debug Sheet Help BSH GS Ba oo T bo n el Fels immediate El Proc Main de Sub Main Learn Mode Started At Thursday October 11 2001 17 46 ATS Application NewTest ATS2 AGen 0utputon True ATS2 Analogin Source apbCh apbAnaloginGenMon ATS Application Page 2 ATS Sweep Start Learn Mode Stopped At Thursday October 11 2001 17 46 End Sub Figure 274 The Macro Editor showing
58. Offset value may be set anywhere in the range be tween 1 0 FS and 1 0 FS if the sinewave amplitude is at full scale the Offset must be O FS Although the sinewave amplitude may be set independently for Channel A and Channel B the Offset value is common to both channels A low amplitude sinewave with an Offset value that positions the sinewave at a major bit switching point of a ladder type D to A converter is particularly useful for testing linearity at various points in the converter s operating range ATS 2 User s Manual 111 Chapter 9 The Digital Generator Choosing a Digital Generator Waveform intermodulation Distortion IMD Intermodulation distortion IMD testing requires a stimulus which is a combination of two waveforms and a specific analysis technique to evalu ate interaction of the waveforms within the DUT Figure 88 Digital Generator IMD Waveform WALTON Selection twim IMD SMPTE DIN 41 pr SMPTE DIM 4 1 SMPTE DIN 1 1 lM Freg 60 0014 Hz id PAI z ATS provides two versions of the SMPTE DIN standard IMD test signals IMD signal amplitude is set in the Digital Generator Amplitude field The IMD composite waveform amplitude is calibrated in peak equivalent sinewave terms See Amplitude Control and Units on page 102 Wfm IMD SMPTE DIN 4 1 This selection produces a signal which is the linear combination of two sinewaves The first sinewave set in the IM Freq field is a lower fre
59. One Files apb Figure 300 Selecting APWIN macro s procedures If you select only one file that macro will be translated and saved and then loaded into the Macro Editor If you select multiple files all the se lected files will be translated and saved in a batch the last macro saved will be loaded into the Macro Editor Each file will be saved with its original filename but the filename exten sion will be changed to atsb the ATS 2 macro filename extension Identifying the System when Importing Macros Commands in AP Basic can have different effects on the three Audio Precision System instruments and for correct macro translation it is helpful if the Translator software knows for which System the original pro cedure was intended Select the System type from the Files of type drop down list as shown in Figure 300 Macro Translator Issues Decisions made in macro translation are based on the same platform differences that determine test translation decisions Mapping Two Ana lyzers into One Analyzer page 421 describes the actions taken by both the Test Translator and the Macro Translator in attempting to map the Audio Analyzer There are a few issues that only apply to macro transla tion however that follow here ATS 2 User s Manual The Macro Translator Appendix F Test and Macro Translators Numbers or Constants ATS commands use language defined constants for many arguments and return values
60. Product Amplitude Chapter 14 The Harmonic Distortion Analyzer These analog domain units are calculated using the value you enter in the V FS field in the References area of the panel and can be helpful in cross domain measurements With Analog selected the units list displays m analog domain units V dBu dBV and W watts m relative units dBr A dBr B dBg A dBg B m and units relative to the digital domain FFS dBFS and FS For an explanation of the units of measurement used in ATS and the ref erences for the relative units see Appendix A Units of Measurement Click the Ratio checkbox of any of the Harmonic Sum meters to select the ratio units dB X Y and ppm for that meter The reference of these ratio units is the Fundamental signal amplitude of that channel References Analog and digital amplitude and frequency references for the Har monic Distortion Analyzer are the same as for other Analyzer instruments See Analyzer Analog References on page 151 and Analyzer Digital References on page 152 Steering Control Figure 210 The Harmonic Distortion Hi Speed a Fired fi 00000 kHz Analyzer Steering References Counter Tuned Sweep Track control field 83 Gen Track Tike Va foe paa a i The Harmonic Distortion Analyzer must identify the fundamental fre quency that you have selected for your measurement The amplitude of the fundamental component is used as the basis of the Ratio measure
61. Q In ATS 2 only two choices are available low 40 Q or high 150 Q or optionally 200 Q or 600 Q 40 Q or 50 Q are always mapped to ATS 2 User s Manual Mapping exceptions and substitutions Appendix F Test and Macro Translators 40 Q Any of the higher impedances are mapped to the whichever high impedance selection is available in ATS 2 Unbalanced output impedances are mapped low to low high to high Test Trans A message will be generated in the log file if the original impedance does not match the translated impedance Macro Trans The higher impedances are mapped assuming that the appropriate hardware option is available If the option is not installed this will cause an error at run time m ATS 2 does not have transformer coupled outputs APWIN settings that specify ungrounded Float configurations will be mapped to the standard ATS 2 output configurations which are grounded Digital Generator m MLS is not supported by ATS MLS selections are substituted with Sine Normal m CCIF DFD and DIM IMD waveforms are not supported by ATS These are mapped to SMPTE DIN 1 1 m Pink and USASI noise waveforms are not supported Noise is used which in ATS available only as pseudo random white noise Audio Input The functions in the APWIN Digital Analyzer panel Input selection control are split into two controls for ATS The ATS 2 Analyzer panel retains the choice between A
62. Receiver Converters Detectors Ranging AC DC Input Coupling q H 4 m CHANNEL B CHANNEL B CHANNEL B CHANNEL B 7 Inputs DIO Analog Input Panel taun A A nnn nunn n nnnm mmEmEmEmMmEMEmMEmMmMEmMEmMEmNEENEE PS A II g Frequency References CHANNEL A Digital CHANNEL A AC DC FREQUENCY Coupling CHANNEL B METERS CHANNEL B CHANNEL A CHANNEL A ee CHANNEL A TENA LEVEL En a 3 METERS B B Filter Ti xl a a Detector Amplitude 9 4 Settings References Selections ues CHANNEL A CHANNELA CHANNEL A Tunable Detectors CHANNEL A pall i Bandpass Ranging _ gt RMS qa RMS p IAEA Filter FUNCTION Tunable METERS Narrow Detectors 5 Bandpass Ranging _ gt mad i MS gt 0 0036 Filter CHANNEL B CHANNEL B CHANNEL B CHANNEL B Measurement Function BANDPASS Audio Analyzer Panel VA A O A fi Se A i a a i a em i la a a A Figure 113 Conceptual Block Diagram Bandpass Function The filter may be tuned to the steering source fundamental frequency or to its 2nd 3rd 4th or Sth harmonic This harmonic tracking ability per mits swept measurements of individual harmonic distortion products lim ited in frequency to a maximum value of 47 of the sample rate The BW high pass and low pass filter selections are not available for the Bandpass function SMPTE DIN IMD Function Figure 114 shows a conceptual block diagram of the Audio Analyzer with the SMPTE IMD function selected SMPTE IMD
63. Sam ple Rates below for more information ap write filter uses the number of remaining arguments to deter mine whether the filter is supplied in second order section form in transfer O ATS 2 User s Manual MATLAB Downloadable Filter Support Appendix D User Downloadable Filters function form in zero pole gain form or in state space form The transfer function form is not recommended for large filters because factorization into second order sections may cause the poles and zeros to move slightly deforming the filter response The total number of bytes written to the file is returned in size Multiple Sample Rates A digital filter will have the intended frequency response only at the sam ple rate for which it was designed Thus a unique filter must be designed for each sample rate that will be encountered If a filter file contains filters for multiple sample rates ATS chooses the filter coefficients corresponding to the sample rate closest to the current hardware sample rate An Audio Precision filter file can contain a filter defined at any number of sample rates Either a file handle or the file append mode can be used to add filters for other sample rates to an existing file ap write filter writes an info string for each sample rate however ATS will only report the first of these strings Filter Restrictions The number of filter orders is limited to 6 for low pass filters 4 for high pass filters and 8 for weighting f
64. Single Point Sweeps External sweeps can also be configured as Single Point sweeps by click ing the Single Point checkbox on the Sweep panel See Single Point Sweeps on page 268 for a full discussion When set up for an External Single Point Sweep ATS will wait until the input signal satisfies all the criteria you have set including Min Lvl the op erative Start On Rule and Settling When the Source 1 reading fulfills these requirements a Data reading will be taken An external single point sweep is useful to extract a single reading under a specific condition or permit an AP Basic macro to continue only at the point that a measured parameter reaches a certain value An X Y graph will not be drawn for a single point measurement The re sult can be viewed in the Data Editor table Time Sweeps In addition to generator sweeps and external sweeps ATS can graph data against time in a Time Sweep producing a chart recorder style mea surement Time Sweeps are commonly used to measure instability or drift of audio parameters over time or to plot moment to moment variations such as wow and flutter or phase jitter To run a Time Sweep open the Source 1 browser and select Time as your instrument and Sweep Time as the parameter The Show Read ings and Show Settings checkboxes have no effect on your parameter choices since you are neither setting a generator nor tracking a measured reading ATS 2 User s Manual 277 Chapter 15
65. The All Bits selection derives the stable reference clock at the actual cell bit rate which is 64 times the audio sample rate All Bits provides the maximum jitter detection analysis frequency range of approximately 1 5 MHz at a 48 kHz sample rate Preambles The Preambles selection uses the average rate of the trailing edge of the first 3 Ul wide pulse in each preamble as the stable clock reference Sig nal transitions at the same point are compared to that average reference to obtain jitter values for display Since this derived reference clock rate is low only twice the audio frame rate the effective jitter measurement band width equals the audio frame rate sample rate when Preambles is se lected Preambles and Stable Bits will result in the lowest residual measure ment jitter Since the 3 UI pulse in a preamble is the most robust portion of the digital interface signal and is least affected by reduced bandwidth in the cable or system Preambles will be relatively immune to cable effects and will be dominated by jitter in the source The filter algorithm used for the Wave Display Interpolate setting requires seven samples of input signal before displaying an output This may make the jitter vs time display show zeros for the first few microseconds Squarewave Converter Clock Jitter Detection In addition to measuring jitter on an AES3 or IEC60958 digital interface signal the Digital Interface Analyzer can also measure jitt
66. This enables you to use actual measured data from a test on one DUT as the limits or standards for a test on a different DUT Instead you may want to use published standards or arbitrary values as your limits In these cases you can enter the data manually into the Data Editor or edit an existing Limit File in the Attached File Editor or create limit values in a spreadsheet or text editor program and import the file into ATS As an example we will create a limit file in the Data Editor First set up a new sweep with two data traces The default sweep starts with only one trace Data 1 to add a second trace go to the Data 3 browser and set it to DSP Analyzer Level B Click Single Point and Go this will inform the Data Editor that you are using two data columns Open the Data Editor The display will have three column headings and one row of data the single point sweep you just performed Click the right mouse button to open the Data Editor menu and add five more rows us ing the Add Row to the End command repeated five times To enter a value click the cursor in a cell and type To make a complete trace you must enter all the Source and Data values necessary to de scribe the limit you want If the Graph panel is open you can view the trace as you create it Create a limit trace by entering the values shown in Figure 241 e Data Editor Miel xl a 0 Digital Gener 1 Analyer Leve Analyzer Leve M 20 0014 Hz 10 000 d
67. a a a a a 62 Single and Dual Connector Input Bitstream Selection 62 Single CONNector Mode 62 Dual CONNECtor Mode 62 Input Sample Rate ISR 63 Voltage coros corridos 63 Input Resolution 00002 ee eee 64 p Law and A law Expansion 64 Deemphasis 0002 ee eee eee 65 Scale Freq by 00 eee eee a eee 65 ATS 2 User s Manual RAUC Rel vanos romana aaa 66 Peak Monitors 0008080888 66 Data BitIndicators 0 048 4 67 Error indicators 67 The Confidence Indicator 68 The Lock Indicator 0 68 The Coding Indicator 202 68 The Parity Bit Indicator 02 68 The Validity BitIndicators 69 Jitter Measurement 69 The Status Bits panel 2 202 0 2208 70 Transmit Status Bits 24 21 Consumer Format Status Bits 72 Professional Format Status Bits 73 Local Address and Time of Day entry 73 CRC entry caros d wee haw ewe eS we ee ws 74 Receive Status Bits 048 74 Hex Control and Display 4 75 Dual Connector Mode and Status Bits 75 Chapter 8 The Analog Generator 77 Test Signal Generati
68. a file name and location Print prints the current graph to your default printer with the current set tings Print Preview provides a preview window of your graph using the cur rent default printer and the current settings Undo allows you to back up one step in your text editing Cut removes the selected text and places it on the Windows clipboard Copy places the selected text on the Windows clipboard ATS 2 User s Manual The ATS Menus Chapter 2 The ATS Control Software Paste inserts text from the Windows clipboard at the cursor location FE Go starts a sweep a Stop ends a sweep X Toggle FFT Time Frequency Domain switches the graph between a frequency domain view spectrum view and a time domain view wave form view for the same input signal acquisition This feature is only avail able while using the Spectrum Analyzer the Multitone Audio Analyzer and the Digital Interface Analyzer ATS 2 User s Manual 21 Chapter 2 The ATS Control Software The ATS Menus The Panels Toolbar A Age fr gps pt SEE Ge cde tN FAR AE oe The Panels toolbar gives you quick access to 17 often used ATS panels This button opens the Analog Generator panel See Chapter 8 This button opens the Analog Input panel See Chapter 6 This button opens the Digital Generator panel See Chapter 9 This button opens the Analyzer panel See Chapter 5 This button opens the Digital Input Output DIO pa
69. align ment takes place in the DSP buffer after acquisition Noisy signals may not be correctly aligned by this mode resulting in am plitude error Triggering with Quasi AC Coupling The Spectrum Analyzer s quasi ac coupling see page 166 occurs be fore acquisition triggering so the selection must be considered when at tempting to trigger on a low level portion of a signal In the synchronous averaging mode the DSP must find a zero crossing in order to time align waveforms for averaging If the waveform contains sufficient dc there will be no zero crossings If this dc is removed before av eraging there will be zero crossings permitting alignment The Subtract Avg mode may introduce error on low frequency signals that could be a problem for the DSP in finding zero crossing locations For well behaved signals the Subtract Y2 pk pk function should produce ac ceptable results References Analog and digital amplitude and frequency references for the Spectrum Analyzer are the same as for other Analyzer instruments See Analyzer Analog References on page 151 and Analyzer Digital References on page 152 The Sweep Spectrum Waveform Button ATS provides a dedicated FFT button for simplified Sweep panel setup and easy switching between frequency domain and time domain viewing This button is called the Sweep Spectrum Waveform button and is lo cated on the Standard Toolbar It is available when the Spectrum Analyzer the Multitone
70. all your Compute settings but simply unchecks the Com pute After Sweep checkbox in every Compute panel Click Add to put a new Compute operation on the list To change the sequence of computations select a Compute operation on the list and click the up or down arrow to move that operation Clear All and Reset The Clear All and Reset command at the bottom of the Compute menu clears all existing settings on every Compute panel Comparing Results with Original Data The Compute operations actually change the current data in memory applying the computations you have selected to the data points you have chosen If you will need your original data again be sure to save it before you apply a Compute operation ATS 2 User s Manual 327 Chapter 19 Performing Computations on Data Comparing Results with Original Data 328 Since the data in memory is changed after a Compute operation a com parison between the original data and the computed result requires that certain steps be taken before the Compute operation is performed One easy way to view both the original data and the computed result is to duplicate the original data in a unused data column for reference pur poses Do this by setting both Data 1 and Data 3 to the same instrument and channel for example before sweeping When your sweep is com pleted you will have the same values in two columns in the Data Editor Now if you perform your computation on Data 1 you can view
71. allows you to choose the input impedance for the digital input The impedance choices are different for the balanced and unbalanced inputs m 110 Q is the low impedance selection for the balanced input which satisfies electrical aspects of the AES3 professional standard m 75 Q is the low impedance selection for the unbalanced input which satisfies the AES3id professional standard m HiZ is the high impedance selection which when used with the unbalanced input satisfies the IEC60958 3 consumer standard HiZ can also be used as a bridging input when ATS 2 is connected in parallel with an external device input with the external device providing the termination Single and Dual Connector Input Bitstream Selection See Figure 26 Single Connector Mode When XLR is selected in the Format field the Connector I Connec tor II buttons allow you to choose either of the two balanced digital inputs for audio and interface measurements Dual Connector Mode When Dual XLR is selected in the Format field the Connector I and Connector II selections allow you to choose either of the two balanced digital inputs for interface measurements The DIO panel input sample rate ISR and Voltage displays the Jitter Measurement reading and all Digital Interface Analyzer measurements of the digital interface characteris tics are of the bitstream selected by the Connector I or Connector II but tons With Dual XLR selected however the Connector I and
72. and Stop Value fields to limit the range of data examined These values only limit the cen tering computation every data point in the trace is moved together When the data is compared to limits for a Pass Fail test all the data spec ified in the data files are used to make the Pass Fail decisions See Limits page 310 Compute Delta Compute Delta calculates the difference or delta between two sets of data ATS can do this in two different ways m by subtracting the data in a specified data file from the current data in memory or m by subtracting the data in one column data trace of the current data in memory from another column of the current data in memory With Compute Delta you can shift your data by an offset using a con stant saved in a file for example or subtract one channel of a stereo signal from the other to measure interchannel differences If you first normalize your trace at O dBV or 1 V at the pivot point you can use Compute Delta to apply an EQ curve to your measurement after the fact See Com pute Equalize below ATS 2 User s Manual 325 Chapter 19 Performing Computations on Data Compute Average Figure 253 Compute Delta Dialog Box First select the Delta Source that is the data to be subtracted from the current data in memory The list under Delta Source initially contains two choices None and SweepData If you want to perform a Delta computation on two data traces of the current d
73. and errors Parity T Invalid Changing the Parity bit This bit will normally be high or low to maintain even parity within the frame Setting a parity error by checking the Parity checkbox will invert the state of the Parity bit bit 31 giving each frame odd parity AESS re quires that parity be even and the DUT should respond to odd parity as if data is corrupt Sending a Validity bit The Validity bit bit 28 will normally be low indicating valid linear PCM audio Checking the Invalid checkbox will set the Validity bit high indicat ing invalid non audio or non linear PCM data Jitter Generation In a digital interface data stream jitter is a variation in time of the pulse transitions from an ideal clock timing ATS 2 can add sinusoidal jitter to the serial interface bitstream Figure 23 The DIO Jitter Generation Jitter Generation ii dither Type Sine Amplitude 50 00 mb Frequency 11 00000 kHz EN Curve ATS 2 User s Manual The DIO Output Section Chapter 7 The Digital I O Panel Jitter Type a Off Off disables jitter generation a Sine Sine modulates the interface transition times with sinusoidal jitter The amplitude and frequency of the sinewave are set in the fields below m EQ Sine EQ Sine adds sinusoidal jitter in the same way as the previous choice but attaches an EQ file to the sinewave This causes the output jitter amplitude to vary as a function of jitter frequency c
74. and precise step sizes which do not need to be regularly spaced The sweep will move in whatever direc tion the values dictate including forward or backward A sweep table is assigned to a sweep by attaching an appropriate AP data file This is usually a file saved as an AP sweep data file with the ex tension atss Click Table Sweep on the Sweep panel to view the file at tachment browser Find the atss file you want to attach to your sweep and select it Other AP data file types can also be attached as sweep files See More About Using AP Data Files on page 314 Before you attach the file you must indicate to ATS which column of data in the table will be your independent variable that is which values will drive your sweep Drop the Column field list on the browser and choose the column If you are not sure which column you want click the Edit button on the browser This opens the Attached File Editor You can view the table in the Attached File Editor and decide which column to choose For more information on using the Data Editor and the Attached File Editor go to Chapter 18 The Attached File Editor is similar in appearance to the Data Editor but the two have different functions When you are ready click OK The table will be attached to your sweep You will notice that the Steps and Stepsize or Multiply fields have disappeared from Source 1 since they are no longer needed ATS 2 User s Manual External Sweeps Ch
75. are used for identification and synchronization of the frames and subframes The X preamble indicates the subframe A beginning the Y pre amble indicates subframe B and the Z preamble indicates subframe A and the beginning of the Channel Status and User blocks Following the preamble are 24 bits reserved for the audio word with shorter audio words the remaining bits are unused although bits 4 7 can ATS 2 User s Manual 385 Appendix B The Digital Audio Signal The Serial Digital Interface Signal be re assigned as auxiliary bits The audio word is arranged with the least significant bit LSB first After the audio word are four administrative bits the V bit Validity the U bit User the C bit Channel Status and the P bit Parity The V bit and the P bit carry data which apply only to their particular subframe If the V bit is 1 the audio data in that subframe is marked as in valid The P bit is set to 1 or O so that even parity is established within the subframe The C and U bits do not carry information about one particular subframe instead these bits are gathered together in blocks of 192 bits The block beginnings are identified by the Z preamble The C bits and the U bits are gathered separately into the Channel Sta tus block and the User block Although Status and User blocks built by subframes A and B usually contain the same information it is possible to carry different Status or User data in the A and B subframes
76. as the Sync Ref in put source Due to this ranging the measured input frequency reading can be in er ror if the input frequency differs by a large amount from the nominal fre quency entered on the Sync Ref panel Enter a nominal frequency close to the actual input frequency If you do not know the squarewave input frequency enter a nominal fre quency of 8 kHz The measured frequency will then display correctly al though with slightly reduced accuracy Now enter this displayed frequency as the nominal frequency and the measured frequency will display cor rectly with full accuracy ATS 2 User s Manual 345 Chapter 22 Sync Ref Trigger and Aux SYNC REF IN 344 Frame Lock As discussed above synchronization of AES3 or IEC60958 rates alone does not time align the interface signal frames Each AES3 or IEC60958 frame begins with a preamble pattern and in time aligned or frame locked signals the X Y and Z preambles start at the same moment When using AES Sync Rate for synchronization in ATS 2 checking Frame Lock time aligns the frames as well The ATS 2 digital output sig nal must be set to the same sample rate as the reference input signal for frame lock Input Termination Impedance Set the termination impedance to 75 Q or terminated if ATS 2 is the only device connected to the reference source or if it is the last device ina chain of devices If ATS 2 is in a chain of devices but is not the last device in the chain
77. at only one value ATS can then acquire the mea surement data for any dependent variables you have set in Data 1 through Data 6 Single point sweeps are often used in AP Basic macros to grab a value or set of values Single point sweep results differ from meter readings in several ways m The single point Data result is dependent upon the Source value specified m The data can be displayed in a tabular format in the Data Editor m The data can be saved as an atsa file and recalled or exported m Sweep settling algorithms and delays can be applied m The data results can be compared against Limit files To make a single point sweep click the Single Point checkbox on the Sweep panel Then select an instrument setting parameter for Source 1 Enter the value at which you want to make your measurement in the Source 1 Start field and set up whatever Data functions you want Since an X Y graph cannot be drawn for a single point measurement the result will only be displayed in a table Select Create Table on the ex panded Sweep panel Click Go and data will be acquired and displayed in the Data Editor table See Sweep Display Mode on page 265 and Data Editor on page 307 ATS 2 User s Manual Nested Sweeps using Source 2 Chapter 15 Sweeps and Sweep Settling Nested Sweeps using Source 2 ATS can generate a family of curves using Source 1 and Source 2 to gether in a nested sweep An ATS nested sweep controls two different set
78. balanced configuration and to 20 Q or 50 Q in the unbalanced Optional European Impedance Configuration With the optional European impedance configuration output impedances can be set to 40 2 or 200 Q in the balanced configuration and to 20 Q or 50 Q in the unbalanced a Optional 600 Impedance Configuration With the optional 600 Q impedance configuration output impedances can be set to 40 2 or 600 Q in the balanced configuration and to 20 Q or 50 Q in the unbalanced Output selection and impedance are set on the Analog Generator panel discussed in Chapter 8 The Analog Inputs The XLR female balanced connectors and the BNC unbalanced connec tors both A and B channels are connected to the ATS 2 analog inputs In put selection is made on the Analog Input panel discussed in Chapter 6 In the standard or European impedance configurations the input load at each of the analog inputs is fixed at a high impedance greater than 100 kQ If you have ordered your ATS 2 with the 600 impedance option an additional field will be shown on the Analog Input panel and you will have the choice of an input load of either 100 kQ or 600 Q This choice af fects both balanced and unbalanced inputs See Chapter 6 ATS 2 User s Manual 37 Chapter 4 Signal Inputs and Outputs The Digital Output 38 We recommend that you do not use both the balanced and unbalanced analog inputs of either channel simultaneously Circuit conditions external
79. be 0 Hz to about 35 MHz Data 1 range about 0 dBV to 100 dBV These will vary according to your require ments signal conditions triggering choices and so on On the Digital Interface Analyzer panel Wave Display can be set to any choice except Eye Pattern Jitter Spectrum The jitter spectrum view shows a spectrum analysis of the jitter signal modulating the interface signal covering a frequency range extending from O Hz to over 1 5 MHz depending on the jitter detection employed ATS 2 User s Manual 195 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Spectrum Views When excessive jitter has been determined to be a problem spectrum anal ysis of the jitter signal is a powerful tool in locating the probable source je O x 10r Ari 2N Tn 500p z0 p 100p 50g 0p 10p 0 200k 400k BOOK ok 1000k 1200k 1400k Hz Figure 156 Digital Interface Analyzer spectrum analysis of jitter signal As indicated in Figure 151 this view requires these Sweep settings Source 1 Intervu Frequency and a Data 1 Intervu Jitter sec or Intervu Jitter Ul Source 1 range should be O Hz to about 1 5 MHz Data 1 range about 1 ps to 20 ns on a log scale These settings will vary according to your requirements signal conditions sample rate triggering choices and so on When jitter signals below 120 kHz are being studied use of the Spec trum Analyzer instrument with the Jitter Signal source will pro
80. be applied to Solid line style traces m Data The Data column shows the ATS instrument and parameter associated with that trace m Axis The Axis column shows whether the trace is calibrated and scaled on the left or right Y axis ATS 2 User s Manual 295 Chapter 16 Graphs Graph Legend Source 2 If Source 2 is used a nested sweep the ATS instrument parameter and value associated with that trace are shown in this column Comment The trace Comment column provides a cell to enter an optional comment for each trace row in the Graph Legend Cursor 1 If cursors are enabled this column shows the value of the associated trace at its intersection with Cursor 1 An asterisk in the cell indicates that the cursor is assigned to that trace a Cursor 2 If cursors are enabled this column shows the value of the associated trace at its intersection with Cursor 2 An asterisk in the cell indicates that the cursor is assigned to that trace The Source 2 column and the Cursor 1 and Cursor 2 columns will only be displayed if these options are in use The Graph Legend box can be resized by dragging its top border with the mouse pointer If the list of traces in the Legend is too long to display scroll bars will appear on the Legend box for navigation Column widths can also be resized by dragging the border between column headings with the mouse pointer Figure 232 Graph and Audio Precision Graph Legend showing data trace and u
81. be inserted between recognition and acquisition of the signal The Trigger Delay field controls the interval between initial rec ognition of the incoming multitone signal and capture of the portion of sig nal which will be analyzed If you set a Trigger Delay be sure that the duration of the multitone burst transmitted is increased by the same amount over the normal mini mum burst duration see Multitone Minimum Duration Require ments on page 232 Phase Measurements Figure 195 Multitone Ch B Phase Ch B Phase hs El selections References The derad100 0 mPFS Eb E Ch 4 By default Multitone results are displayed as amplitude vs frequency plots To measure phase select Fasttest ChA Phase or Fasttest ChB Phase or both as a Sweep Data instrument Most multitone waveforms and all of the multitone samples provided with ATS 2 have had the phase of each tone shifted randomly to reduce the crest factor of the waveform In ATS 2 this process is called phase ran domization Waveforms that have had this process applied will not return ATS 2 User s Manual References Chapter 13 The Multitone Audio Analyzer valid phase results with one exception mentioned below in Channel B Phase You can create your own multitone waveforms for phase tests without randomizing the phase by unchecking the Minimize Crest Factor checkbox on the Multitone Creation Utility dialog box Such waveforms will have a high crest f
82. between the highest peak in the multitone waveform and digital full scale m Multitone Waveform Length Choose from this list the length of one period of your multitone waveform 8192 samples is a typical choice The Multitone ATS 2 User s Manual Creating Multitone Waveform Files Chapter 13 The Multitone Audio Analyzer Waveform Length cannot be longer than the Record Length below Record Length Choose from this list the total file length for one channel if a stereo waveform for your multitone 8192 is a typical choice The file may contain multiple periods of the multitone waveform On the left of the panel are four checkboxes m Create Sweep Table File This option generates a sweep table file with entries corresponding to each of the tones in the multitone file m Create MS RIFF wav File In addition to any Audio Precision generator waveform files this option generates a Microsoft wav sound file containing the same multitone waveform as the agm or ags source file Minimize Crest Factor A complex waveform such as a multitone can have a high crest factor making a low rms level necessary to prevent overload Different phase relationships among the component tones can reduce the crest factor The Minimize Crest Factor command enables an automatic feature which randomizes the phase relationships of the component tones repeatedly then chooses the result with the lowest crest factor In the small entry field to the rig
83. button functions ATS 2 User s Manual 23 Chapter 2 The ATS Control Software ATS Add Ins 24 The Quick Launch Toolbar Quick Launch ES Quick Launch allows you to create and use custom toolbar buttons to open ATS tests run AP Basic macros and even launch other Windows pro grams From the Main menu choose File gt Quick Launch gt Customize Quick Launch to open the Quick Launch Configuration panel where you can view or edit the existing Quick Launch commands or to add new commands of your own Figure 5 Select a quick launch item from the list below The Quick Launch Configuration panel Analog Frequency Resp SATSATS 2 Analog Distortion vs Freg VATSSATS 2 4 4Mnal ENB Analog Signal to Noise A VATSSATS 244 4MAnal T FFT Spectrum Analyzer VATSSATS 2 4 4MAnal FASTTEST Multitone an ATSNATS 2 4 A Anal lt none gt M A Digital Interface Analyzer C ATS IntervuMenu apb lt none gt fa log F R N Menu Text nalog Frequency hesponse Aa Command ATS ATS 2 4 4 inalog FREQ RESP FASTTE Ej IV Automatically run when loaded Cancel Am For each toolbar command enter or browse to a command line with a complete path in the Command field Then name the command in the Menu Text field and choose toolbar button icon with be browser next to the Menu Text field If you would like a macro from the Quick Launch toolbar to run immediately check Automatically ru
84. can also create your own waveform files using the Multitone Cre ation Utility See Creating Multitone Waveform Files on page 236 Multiple Synchronous Tones in One Waveform The lowest synchronous frequency for an FFT is the frequency for which one cycle fits exactly in the transform buffer calculated by divid ing the signal sample rate by the transform length in samples For ex ample a sample rate of 48 kHz and a transform length of 8192 samples gives a base frequency of 5 859375 Hz That frequency and all integer multiples of that frequency are valid tones to use in a 48 kHz multitone waveform being measured by an FFT analyzer using an 8192 sample acquisition Fortunately if you decide to create custom waveforms all these cal culations are done for you by the Multitone Creation Utility See page 236 Inside Information Multitone Generator Settings _ To make multitone analysis fast and consistent the Multitone Audio Ana lyzer in ATS 2 requires information about the nature of the multitone file in use The Analyzer must know what tones are in the multitone waveform the sample rate at which they were generated etc In most cases this infor mation is passed from the ATS 2 generator directly to the Multitone Ana lyzer with no user input needed This is not possible when the multitone waveform is being played from an audio tape or a CD or if it is being transmitted from a remote location In these cases you mu
85. can be ordered with the Performance Upgrade Option installed which includes an additional pair of converters the 16 bit high bandwidth ADCs These converters offer considerably higher sampling rates and avail able signal bandwidths at the trade off of less resolution The standard 24 bit converters provide 10 dB to 15 dB better residual distortion If the high bandwidth ADCs are installed three more choices will be available on the drop down list u HiBW 131072 Hz When set at a sampling rate of 131 072 Hz the frequency response of the analog inputs extends to 60 kHz ATS 2 User s Manual Converter and Sample Rate Selection Chapter 6 The Analog Input Panel es HiBW 262144 Hz At this sampling rate setting of 262 144 Hz the frequency response of the analog inputs is extended to 120 kHz m HiBW 2xOSR This setting uses the high bandwidth ADCs but the value of the sampling rate is taken from the Output Sampling Rate OSR setting on the Digital Input Output DIO panel Some tests such as DSP multitone analysis require that the digital signal applied to the DSP be synchronous with the OSR and this selection provides that synchronization with the high bandwidth ADCs See Chapter 7 The Digital I O Panel ATS 2 User s Manual 49 Chapter 6 The Analog Input Panel Converter and Sample Rate Selection 50 ATS 2 User s Manual The Digital I O Panel This chapter discusses the Digital I O panel also called the Digital In put Out
86. can enter values in the Start Value and Stop Value fields to limit the range of data examined These values only limit the straight line computation after the line is derived every data point in the trace is sub tracted from the line value Since the values of the data linearity deviations are often small you may want to optimize the graph view for better resolution See Optimize page 288 Compute Center Compute Center can only be used with data sets that have both up per and lower limit files attached See Limits page 310 Compute Center moves the data trace to center it evenly between the upper and lower limits This is useful in situations where the shape of the curve and its general agreement with the limits are more important consid erations than the absolute amplitude of its data points 322 ATS 2 User s Manual Compute Delta Chapter 19 Performing Computations on Data Figure 252 Compute Center Dialog Box Center Data to Compute T Apply After Sweep Bo start value Data 2 20 0000 Hz Datas Stop Yalue Data 4 20 0000 kHz Data 5 Data 6 Compute Cancel Close Compute And close For example in comparing microphones an evaluation of the overall mi crophone response as compared to limits is often more important than fo cusing on any minor level differences which may exist To keep data from the measurement extremes from skewing the center ing process you can enter values in the Start Value
87. correct result in an Independent phase measurement Tight Normal and Loose Tight Normal and Loose triggering are for use when receiving a multitone waveform that is not currently being output from an ATS 2 gen erator a waveform from an audio recording or a distant transmitter for example As mentioned before the same multitone waveform that is being received must be loaded into the generator The Multitone Analyzer com ATS 2 User s Manual 229 Chapter 13 The Multitone Audio Analyzer Phase Measurements 230 pares the incoming signal with the multitone waveform in memory to de cide when to begins its acquisition Normal is the recommended setting for receiving an external multitone If the signal is degraded and will not trigger properly Loose relaxes the triggering criteria and may provide more consistent triggering Tight en forces the criteria more strictly and will provide better triggering when the multitone burst is very short or when program material on the line might cause false triggering Trig In Ext The Trig In Ext triggering selection responds to a trigger event at the Trig In Ext connector on the ATS 2 rear panel Trigger Delay Audio processors compressors limiters etc require time to stabilize fol lowing any change of level such as between the multitone burst and the preceding program material If you need to allow processors in an audio chain to stabilize before mea surement a delay can
88. coupling 182 FFT triggering with synchronous averaging ee ee re ee ee ee ee 181 FFT windows 397 Digital Interface Analyzer 207 Spectrum Analyzer 161 FFT synchronous 399 FFTsoverview 2 393 File e owe tba EGG 26 MACRO 2244 6 ee te eee A 25 CESE ead be endh oe tae oe eat 25 File Menu 0 13 Filters user 401 Fixed range see ranging meter Flat top FFT window Digital Interface Analyzer 208 Spectrum Analyzer 163 Floor Settlin9Q 282 Fitr field function meter 145 Frame digital audio signal 385 Frequency counters see frequency meters Frequency meters Analog Analyzer 128 Frequency steering control Harmonic Dist Analyzer 251 Frequency units 79 101 379 Frequency generator reference 122 Frequency Time domain toggle button 182 Frequency domain view see Spectrum Analyzer FS digital full scale 376 Function keys 27 Function meters 2 130 Function monitor outputs 340 Fundamental amplitude meters Harmonic Dist Analyzer 248 Fundamental frequency meters Harmonic Dist Analyzer 248 F weighting filter see weighting filter G Gaussian FFT window 164 Generating test signals 77 99 GENM
89. cycle checkbox in the Configuration panel is checked each new sweep will assign colors to the Data sets in this way whether or not you have made manual color changes in the Graph Leg end If the Reset color cycle checkbox in the Configuration panel is un checked ATS will use this assignment of colors initially If you manually change any color to Data assignment ATS will maintain your new color assignments throughout subsequent sweeps See Chapter 25 Configuration Color Cycling in Nested and Appended Sweeps When nested or appended sweeps are made each Data trace in each sweep follows the color cycle pattern picking up at the place in the pattern where the same Data trace of the previous sweep left off For example a Data 1 trace which was green in a particular sweep would be displayed in yellow in the next appended or nested sweep ATS 2 User s Manual 299 Chapter 16 Graphs Figure 234 Traces automatically sequence through the color cycle for appended data and nested Sweeps Am Axis Ce e Audio Precision a a agama tS aii Blue Solid Gray Solid Cyan sold Green F Solid Yelow Solid Red Solid Magenta Solid Trace Colors al ES 2k 5k 20k E Analyzer Level B Left gt AnalyzerLevel B Lef Analyzer Level B Left AnalyzerLevel B Lef Analyzer Level E Left Analyzer Level B Lef Analyzer Level B Left Analyzer Level B Lett a 0 oom AA e a hd i
90. dB below a nominal zero level These upper and lower traces could be saved in a Limit file as upper and lower limits for subsequent tests of other units Figure 248 Compute Normalize Normalize Dialog Box otto Compte Boi Aer Sep M Data1 Horizontal value Data 2 ji 00000 kHz Data 3 E j Target value Data 4 15 000 dBu FT Data 5 Data 6 Compute Cancel Close Compute And close To normalize a trace you must select the horizontal X axis value of the data point you want to be the normalized reference and then enter the Y axis value you want as a target value In the case of the golden unit to make an upper limit you might choose 1 kHz as the Horizontal Value and 3 dB as the Target Value ATS 2 User s Manual 319 Chapter 19 Performing Computations on Data Compute Invert You may normalize more than one trace to the same Target Value by checking the appropriate Data checkboxes However all the traces se lected must be of the same unit domain as the Target Value Compute Invert Compute Invert turns a curve upside down Specifically Compute Invert reciprocates data expressed in linear units and negates data ex pressed in decibel units A typical application is to invert a measured frequency response and save the inverted trace as an EQ file which can then be attached to a sweep to correct for system response variations Figure 249 Compute Invert Dialog Box Invert D
91. digital full scale Multitone Measurements Once a multitone signal has been routed through the DUT an acquisi tion is made and an FFT is performed The Measurement field selects the type of post processing performed on the FFT results before they are dis played or compared to limits Figure 178 Multitone Measurement E Spectrum selections Spectum Freg Resolution Response Distortion FFT Length Noise Processing Masking Curve Crosstalk Frequency Domain Views by default The display for each of these measurement modes is by default a fre quency domain view plotting the results on amplitude vs frequency graph Spectrum and Response measurement results can also displayed as phase vs frequency plots by choosing a Fasttest Phase instrument in the Sweep Data browser ATS 2 User s Manual Multitone Measurements Chapter 13 The Multitone Audio Analyzer Spectrum Figure 179 shows a diagram representing an FFT spectrum display of the signal at the DUT output for our example multitone of Figure 174 Note that the illustration shows that the DUT has modified the response and has added noise and distortion to the signal Figure 179 Example of a peepee multitone spectrum display F1 F2 F3 F4 F5 F6 F7 F8 F9 F11 The ATS Spectrum Multitone Measurement selection provides a nor mal FFT spectrum display with no processing except for peak picking see page 176 when necessary Since Spectrum mode shows t
92. ee 177 Triggering on senos rones 177 Free RUN aaa aaa a a eee 178 AULO oh ee eee ee ee dew hee sees aserrean 178 Fixed Sensitivity 2 2000802 a 178 TrigIN EXD 2 ee 179 Digital Gen 179 Analog Gen 002 eee eee ee ee 179 Line Mains 000 eee ee a 179 Jitter Gen 0020 0 0 0 2 00000 2 eee eee 179 Fixed Level 179 Trigger Delay Time 208 4 180 THIGGErSIODEG osas prosas a a 180 Triggering with Synchronous Averaging 181 Without Re alignment 181 With Re alignment 2 08 181 Triggering with Quasi AC Coupling 182 References 182 The Sweep Spectrum Waveform Button 182 Acquired Waveform Files 2004 183 Saving Acquired Waveforms 184 Opening Acquired Waveforms 184 Combining Mono to Stereo 185 Compatibility of Acquired Waveform Files 185 Chapter 12 The Digital Interface Analyzer 187 OvervieW 2 00 ee ee ee 187 ATS 2 Digital Interface Analyzer Analysis Tools 187 Digital Interface Analyzer Components 188 The Digital Interface Analyzer ADC 188 Digital Interface Analyzer Capabilities 188 Loading the Digital Interface Analyzer 189 The Digital Interface Analyzer panel 189 Digital Interface Analyzer Wav
93. effective until you save the file To save a file from the Attached File Editor close the edi tor window A dialog box will open and prompt you to save the file The file is always saved under its current file name overwriting the previously saved file The commands on the File menu File gt Save gt Limit etc save the data in current memory not the edited data in an attached file Close the Attached File Editor to properly save this data Actions Upon Failure A pass fail test fails when the measured data exceeds a limit value dur ing a test Depending upon the system settings and configuration ATS will indicate a limit failure in several ways u Terminate Sweep Normally the sweep will continue even if limits are exceeded However if you click the Terminate Sweep on Failure box on the Limit File Attachment dialog box the sweep will end if a limit is exceeded a Tabular Display Flags Any measurement that exceeds a limit will be marked with a U for upper or an L for lower in the Data Editor table See Data Editor page 307 m Log File Indicators If Log Errors is set in the Configuration panel limit failures will be shown in detail displaying Source Data and Limit values and the amount and sign or of the error for each limit failure See The Log File page 364 More About Using AP Data Files Data files include the four types listed on page 310 Data saved to any of these filetypes is maintained in an ide
94. excursions of the signal See Graphic Aliasing on page 176 If you use the graph Zoom and Zoomout commands the time span represented on the graph changes When Interpolate is selected Wave Display automatically switches between bipolar peak sensing mode and in terpolation mode for the best display The Interpolate selection produces a much more accurate display of the signal waveform than the Display Samples mode when the signal fre quency is high such as sample rate 100 or higher Display Samples When Display Samples is selected for each display point requested the DSP sends the amplitude of the nearest in time acquired sample to the computer for plotting Acquisition points may be repeated or dropped de pending upon the relationship of acquisition point density to display point density When the signal frequency is low compared to the sample rate this may produce an acceptable representation of the original signal waveform At high signal frequencies the waveform may be entirely unrecognizable in the Display Samples mode because of graphic aliasing see page 176 Interpolation mode should normally be used in this case ATS 2 User s Manual 203 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer panel settings 204 Peak Values When Peak Values is selected the DSP searches all sample amplitudes in the acquisition buffer between each pair of X axis time values plotted and sends to the computer for plo
95. exercised at 997 Hz as desired and the frequency correction yielded an unwindowed FFT with high selectivity as if the signal had been at the synchronous frequency of 996 09375 Hz The frequency correction technique has a maximum correction range of 4 At the low end of the frequency range there will be frequencies which are more than 4 from a bin center For example with a ATS 2 User s Manual 165 Chapter 11 The Spectrum Analyzer Quasi AC Coupling 166 16 384 sample transform and 48 kHz rate 37 Hz is approximately the lower limit above which a sinewave at any arbitrary frequency can be guar anteed to be brought to a synchronous frequency The technique will work at still lower frequencies if the signal frequency is within 4 of a synchronous bin center frequency Bin center frequencies may be computed from the equation Nx Sample Rate Frequency 4 Transform Length where N is the integer number of cycles in the transform For example with N 7 exactly seven complete cycles in the FFT buffer a transform length of 16 384 and a 48 kHz rate the synchronous frequency is 20 5078125 Hz A 4 range around that frequency extends from approximately 19 7 Hz to 21 3 Hz and a sinewave within that range will be corrected to the synchronous frequency When using Sweep Append and Sweep Repeat with None move to bin center as the Window selection the frequency shift will be per formed only once and not with every Append or
96. familiar with Visual Basic you will find many similarities in the languages you can also use programs written in Visual Basic to control ATS 2 Using AP Basic you can write macros automation programs also called scripts or procedures which issue ATS OLE commands open files wait for data readings to satisfy necessary conditions create reports save information to disk and communicate with other Windows programs You can design and use custom user interfaces to simplify macro operation and guide operators through a process Using OLE it is possible to control ATS 2 from other programs such as word processors or spreadsheets Virtu ally every function of ATS 2 can be automated with AP Basic AP Basic macro files for ATS 2 are saved with the filename extension atsb Learn Mode An experienced programmer with a good knowledge of AP Basic can sit down at a text editor and write a macro to run an ATS test It s much eas ier though to use Learn Mode ATS 2 User s Manual 351 Chapter 23 Automating Tests The Macro Editor 352 Learn Mode records every appropriate operation of the ATS software to an AP Basic macro file It is similar to features in other applications called macro recorders Learn Mode is often the easiest way to create a macro whether simple or complex To enter Learn Mode click the Start Learn Mode button on the Learn Mode toolbar or from the Main menu choose Macro gt Learn Mode or Utilities gt Learn
97. field is labeled Fltr and provides weighting filter selections for some instrument functions and detailed control over the bandpass bandreject filters for other functions Graphs of all the filter curves are shown in the Specifications chapter in Getting Started with ATS 2 BW The Highpass Filter Figure 119 The Audio Analyzer Det Auto E BP BR Fltr Freq BW Highpass Filter Sweep Track dBr B 387 3 mi a wFs O00 dE mJe00 0 Ohme ATS 2 User s Manual 145 Chapter 10 The Audio Analyzer The Function Meters 144 There are two BW bandwidth filter control fields The left field is the highpass field The highpass filter is effective in all Function meter functions except Crosstalk Bandpass SMPTE and Phase This field allows you to se lect essentially flat response at low frequencies the lt 10 Hz selection spe cific highpass filters at 22 Hz 100 Hz 400 Hz or a User HP A highpass filter when selected is connected in the measurement paths of both Function meter channels but does not affect the Level or Fre quency meters The 22 Hz and 100 Hz high pass filters are four pole 24 dB octave de signs in all functions of the Function meter In the two THD N functions the 400 Hz filter also is four pole how ever in the Amplitude or 2 Ch Ratio functions the 400 Hz filter be comes an extremely sharp high rejection ten pole elliptical high pass filter Selecting the 400 Hz filter in these functions p
98. frequency on the Analog Generator panel turn the generator ON then close the panel window The signal will continue at the settings you ve made until you open the panel again and turn the generator OFF Many of the ATS panels come in two sizes the smaller having fewer commands and readouts visible and the larger showing every option The most commonly used size for each panel is set as its default size Dou ble click on the panel title bar to expand or contract it Panel Settings Settings for tests and measurements are made using several different types of controls on the panels m Setting fields which come in several versions e First is a text box in which you can directly enter a value from the Freg 397000 kHz keyboard e Second is a drop down list box in which you can make a Bits selection from a set of choices ATS 2 User s Manual 11 Chapter 2 The ATS Control Software The ATS Panels fi OOO Vime a e Third is a combination of the first and second a text box with an 1 000 Wms added drop down list from which you can choose the units to Le Ma express your value See Appendix A Units of Measurement pp Setting fields display dark black or blue text or numbers on a white field Ji F m Check boxes which allow you to set non exclusive conditions Out Ohms l ean c 200 m Option buttons which provide for exclusive conditions m Browser buttons which open dialog boxes called browsers
99. high bandwidth analog to digital converters to extend the analog analysis bandwidth from 30 kHz up to 120 kHz and an additional Analyzer instrument called the Digital Interface Analyzer that can more closely examine the interface signal providing eye patterns histograms waveform display and FFT spectrum analysis of the recovered jitter signal and triggering from a number of different interface patterns and bits Conceptual Architecture of ATS 2 1 Pal HIGH RES ANALOG I O DSP i i HIGH BW ADC JITTER DETECTOR So INTERFACE MEASUREMENT AES 3 INPUT pall AES 3 B f OUTPUT STAGE DIGITAL TROGER OUT JITTER I O DSP Mur UTILITY OUT UTILITY OUT CoM APIB INTERFACE o AES 3 INPUT TV SYNC DETECTOR SAMPLE RATE CONVERTER PRECISION SAMPLE RATE RECEIVER GENERATOR PROGRAMMABLE diri DIVIDER VARIABLE SAMPLE RATE GENERATOR Figure 2 ATS 2 conceptual block diagram The functional components implemented in ATS 2 include two DSP im plemented audio signal generators a suite of DSP implemented audio data and interface signal analysis capabilities digital and analog input and output modules and modules for synchronization and APIB communica tion All signal generation is performed in the digital domain One of the two DSP signal generators is dedicated to the digital output The signal from this generator called the Digital Generator is routed through t
100. in control and measurement win dows called panels These can be thought of rather like the physical con trol panels often found on conventional test and measurement equipment with range function and trigger controls ON and OFF switches linear ad justment pots and sliders numerical meter readouts bar meters X Y wave form displays graphs and so on The ATS panels are available through menu commands toolbar icons and keyboard shortcuts You can control ATS 2 from just one or two ATS panels if that s all your measurement requires A more typical test might involve four or five pan els a complicated test perhaps six or seven ATS 2 User s Manual The ATS Panels Chapter 2 The ATS Control Software Figure 4 ll Analyzer x An ATS Instrument Panel Instrument Audio Analyzer ChA Input Analog Che Lia Level EA Freq al Range Iv a AA Function La Eg Measurement Function Amplitude Range Iv zj Det Auto E BP BR Fltr Freg Bue lt 10 Ha Fsr2 Fite None a E References dBr amp 387 3 mi dB B f387 3 mi a Fred 0000 kHz wisi O00 Y twatts 8 000 Ohms dBm en0 0 Ohms Although the ATS panels can all be placed on one workspace page most users prefer to organize their workspace by placing panels on several different pages You can close a panel without canceling its function or effect for exam ple you could set a signal s output voltage and
101. inputs simultaneously Circuit conditions external to ATS 2 could degrade the system performance However a connection to the optical input can be maintained simultaneous to a connection to either the balanced or unbalanced digital input The DIO panel will select only one input at a time Electrical vs Data Characteristics Across Formats The various standards defining digital audio interface formats cover a broad number of characteristics including line impedance signal voltage acceptable rise time and jitter figures and also the information carried as data on the interface Although the ATS 2 balanced and unbalanced digital connections do sat isfy the electrical requirements for certain standards as mentioned above selecting the balanced or unbalanced digital input or output does not con figure the digital data stream This is done in other fields on the DIO panel ATS 2 User s Manual 39 Chapter 4 Signal Inputs and Outputs The Digital Input and on the Status Bits panel See Chapters 7 and Appendix B for a full dis cussion of the digital data stream and status bits It is entirely possible to route digital audio data configured to the profes sional format standard AES3 to the unbalanced output with voltage and impedance characteristics matching the consumer format standard IEC60958 3 as it is possible to route consumer formatted data to the bal anced output at the professional format voltage levels and impedance val
102. intermodulation distortion to the SMPTE or DIN stan dards measures the amplitude of the IMD residuals created below the high frequency component of a two tone test signal These are recovered by first passing the signal through a 2 kHz high pass filter and then demod ulating and filtering the sidebands Appropriate two tone test signals can be generated by the Analog or the Digital Generator The combined ampli ATS 2 User s Manual 157 Chapter 10 The Audio Analyzer The Function Meters tude of the recovered sidebands is stated as a ratio to the amplitude of the high frequency tone with units of or dB being the most common The BW high pass and low pass filter selections are not available for the SMPTE DIN function CHANNEL A PEAK 1 423 Vp METERS m n n 2 1 we 0 1 y i CHANNEL B CHANNEL A CHANNEL A CHANNEL A CHANNEL A A to D Peak Anaoa Anang a a a fae Ranging AC DC onverters etectors Coupling A Inputs 4 CHANNEL B CHANNEL B CHANNEL B CHANNEL B DIO Analog Input Panel n Frequency ESS CHANNELA Digital CHANNEL A AC DC 80 000 Hz FREQUENCY Coupling METERS CHANNEL B CHANNEL B CHANNEL A CHANNELA Detectors CHANNEL A Ranging RMS 830 4 mV J LEVEL amp rasi RMS CHANNEL B METERS CHANNEL B CHANNEL B Detector Amplitude Settings References CHANNELA CHANNEL A CHANNEL A CHANNELA CHANNELA CHANNELA 2 kHz
103. is discussed below Look in the ATS 2 User s Manual for m Detailed discussions of every ATS 2 feature and every software panel control and display 2 ATS 2 User s Manual ATS 2 Capabilities Chapter 1 Introduction m Reference information on audio test and measurement techniques sample and utility file listings and much more A copy of the ATS 2 User s Manual is shipped with every ATS 2 system The manual is also published as a PDF on the Audio Precision Resources Disc and on our Web site at ap com ATS 2 Capabilities ATS 2 is a comprehensive high performance audio testing system m ATS 2 can make amplitude frequency THD N noise phase crosstalk bandpass and IMD measurements for analog or digital audio devices and can perform a detailed analysis of individual harmonic distortion products m AIS 2 can perform measurements on audio signals using fast Fourier transform FFT analysis with advanced high speed FFT analysis techniques available including multitone recognition and analysis capability frequency adjustment for bin centering synchronous FFT processing and advanced post FFT analysis FFT analysis can also provide time domain oscilloscope type waveform display of signals Non audio signals such as interface signal jitter components can also be studied with FFT techniques m ATS 2 can use a combination of different measurement instruments and parameters to perform complex sweeps and can display and print the
104. is made and no new transform is performed For the time domain view F6 and Ctrl F6 have the same result Making a new acquisition is usually the most time consuming step in the process performing the transform is next and processing the results for dis play is usually the fastest step When time becomes an important consider ation as in repeated automated processes you should take care to include only necessary FFT steps 158 ATS 2 User s Manual The Acquisition Record Chapter 11 The Spectrum Analyzer The Acquisition Record Figure 131 ATS Spectrum Analyzer FFT E 92 Acquires Track FFT j Track FFI Lo Acquire selections es dom Esuiipple as z1 UE Trigger Delay 0 00000000s Cr mal Free Aim laa See Appendix C for a conceptual overview of FFTs including a discus sion of the acquisition record and FFT length In performing an FFT ATS 2 first acquires data taking a brief sample of the signal to be analyzed This acquired data is called the acquisition re cord and it is stored in a location in ATS 2 s DSP memory called the acqui sition buffer The two channels of a stereo acquisition are maintained in two separate acquisition buffers Acquiring the data and performing the FFT are two separate steps You can choose to acquire new data with each execution of an FFT or you can re transform the same acquired data repeatedly using different processing or timing settings with each FFT When usin
105. it against Data 3 which displays the reference duplicate of the original data ATS 2 User s Manual Chapter 20 Printing and Exporting ATS graphs can be printed to any Windows compatible printer in black and white or in color As an option the underlying data can be also printed as a table ATS graphs can be copied to the Windows Clipboard as well in either bitmap or vector graphics format Graphs can also be directly exported as a Windows Metafile or Enhanced Metafile ATS panels can be captured as bitmapped screen shots by the Edit gt Copy Panel to Clipboard command on the Edit menu Once the panel is on the Windows clipboard it can be pasted into a word processing pro gram such as Microsoft Word or into one of many paint or draw graph ics programs for editing or printing Printing ATS Graphs When printing an ATS graph the key information shown on the graph panel is carried through unchanged to the printed page This information includes m the parameters to be graphed and m X axis and left and right Y axis calibrations and scaling This information cannot be changed from the print menus However display aspects of the graph can be made independent of the graph and elements such as trace visibility color and line style graph la beling and legend graticule visibility and so on can be modified at print time These changes are made on the Page Setup panel ATS 2 User s Manual 329 Chapter 20
106. kHz 48000 12 m 3 42857 kHz 48000 14 and so on White Noise Figure 90 Digital Generator Noise Digital Generator fel Waveform tine Tm Wfm Noise The ATS 2 Digital Generator offers a DSP generated white noise signal The DSP generated noise is pseudo random and has a length of 2 or 1 048 576 samples which means that with the DIO OSK set to a sam pling rate of 48 kHz the noise pattern repeats about every 22 seconds The noise has a zero mean a crest factor of 1 73 and a rectangular probability distribution function The spectrum of the noise is flat from just above O Hz to just below half the sampling rate and consists of spikes spaced at SR 2 Hz ATS 2 User s Manual 113 Chapter 9 The Digital Generator Choosing a Digital Generator Waveform 114 White Noise Characteristics The spectral distribution of white noise is characterized by equal noise energy per hertz This means that the spectral range between 100 Hz and 200 Hz will have the same energy as the range between 10 000 Hz and 10 100 Hz If analyzed by a constant bandwidth spectrum analyzer such as a superheterodyne or FFT analyzer white noise will show a flat energy characteristic versus frequency up to the bandwidth limitation Analysis of white noise with a constant percentage bandwidth con stant Q filter such as in the Audio Analyzer Bandpass mode or as in most real time analyzers will show a rising characteristic versus fre quency
107. maximum Burst On duration is 65 535 cycles of the sine waveform if Interval is set to its maximum the minimum is 1 cycle Burst On can be set in units of Cycles or s B seconds Burst Only Burst On durations which are less than the Interval durations can be entered ATS 2 User s Manual 85 Chapter 8 The Analog Generator Choosing an Analog Generator Waveform a Interval Enter a value in the Interval field to set the period between the onset of the tone burst and the onset of the next burst The maximum Interval is 65 536 cycles of the sine waveform the minimum is 2 cycles Interval can be set in units of Cycles or s B Interval does not describe the time between the end of a burst and the beginning of the next but the entire period from the beginning of one burst until the beginning of the next m Low Level When a tone burst is ON the level of the sinewave in the burst is the same as the current Amplitude setting for the Analog Generator When a tone burst is OFF the low level is the ON level multiplied by the value set in the Low Level field The OFF level is a ratio of the ON level set here in units of X Y ratio dB per cent or PPM See Ratio Units page 378 If Low Level is set to equal the burst high level amplitude no burst effect will occur and the output will be a continuous sinewave At large amplitude ratios the amplitude resolution of Low Level becomes poorer The display will show the actual available resolution st
108. mean a crest factor of 1 73 and a rectangular probability distribution func tion The spectrum of the noise is flat from just above O Hz to 60 kHz The noise waveform amplitude is calibrated in peak equivalent sinewave terms See Amplitude Control and Units on page 80 White Noise Characteristics The spectral distribution of white noise is characterized by equal noise energy per hertz This means that the spectral range between 100 Hz and 200 Hz will have the same energy as the range between 10 000 Hz and 10 100 Hz If analyzed by a constant bandwidth spectrum analyzer such as a superheterodyne or FFT analyzer white noise will show a flat energy characteristic versus frequency up to the bandwidth limitation Analysis of white noise with a constant percentage bandwidth con stant Q filter such as in the Audio Analyzer Bandpass mode or as in most real time analyzers will show a rising characteristic versus fre quency at the rate of 3 dB per octave ATS 2 User s Manual Choosing an Analog Generator Waveform Chapter 8 The Analog Generator Arbitrary Waveforms 4 Analog Generator Of x Wim Arb wim y Look in GJ WAVEFORM Jol al alae D Auto On EF el ci mls 1 000 Vims 32K a 1K 0 44 agm a 40010048 agm a 400 2048 4K a 1K 0 48 agm laa 40011044 agm a 400 3 44 2 48K laa 2K_fm60 agm sa 40011048 agm a 400 3 48 2 ls 1415tt44 agm a 400 0 44 agm a 40012044 agm a 400 4044 Sa
109. ms Audio Precision Ml ES 10m Figure 96 Monotonicity waveform 24 bit word width 10 samples step 48 kHz sample rate Dither is disabled when the Monotonicity waveform is selected The Monotonicity waveform is used principally in testing low level linear ity of D to A converters and digital domain devices by viewing their output in the time domain using the Spectrum Analyzer instrument In the Spectrum Analyzer instrument panel Select Digital Gen as the Trigger Source The Wave Display field on the panel should be set to either Display Samples or Absolute Value but not Interpolate See Chapter 11 for more information about using the Spectrum Analyzer Non linearity is shown by unequal step to step amplitudes Non monotonicity is indicated by a reversal in direction of the pattern of constant decrease from step to step ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator Wfm Special J Test J Test is a waveform which produces a maximum amount of data in duced jitter on low bandwidth digital transmission links J Test consists of a squarewave at one fourth the sample rate combined with a second low frequency low amplitude squarewave that has a digital DC offset Dither is disabled for J Test and no amplitude control is available since the signal definition specifies exact data values The J Test signal would normally be transmitted while measuring jitter at the receiving
110. no window Flat Top window Hann window and finally adjusted very slightly in frequency to 799 805 Hz to be synchronous Graphing FFTs ATS 2 FFT results are usually displayed as graphs In ATS the number of samples in the record and the number of points or steps requested for the graph not necessarily the same You can set up an FFT length of only 256 samples and a graph of 5000 steps or an FFT 32 768 samples long displayed on a graph of only 10 steps The FFT length is determined by your frequency resolution needs and the time involved in acquisition 16 384 samples is a typical choice Here are some guidelines to selecting the number of graphed points m Use the fewest steps which result in a useful graph Fewer steps provide faster operation m There is no purpose in graphing more points than you have samples a 128 point FFT graphed at 512 steps will display 384 redundant points If your end use is a graph on a screen or printed on paper there is no purpose in graphing more points than your monitor or printer can display Selections of 500 to 1000 points typically provide excellent graphs m If your end use is a table you may want to specify more graph steps than mentioned above if you have a high resolution FFT and you would like a detailed table of values 400 ATS 2 User s Manual Appendix D User Downloadable Filters Creating User Downloadable Filters A User Downloadable Filter consists of a properly form
111. number within that mode digital audio reference 00 nota DARS signal DARS 10 DARS grade 2 10 ppm 01 DARS grade 1 1 ppm sampling frequency 0000 not indicated 1000 24 kHz 0100 96 kHz 1100 192 kHz 1001 22 05 kHz 0101 88 2 kHz 1101 176 4 kHz 1111 User defined sampling frequency 0 no scaling scaling 1 apply factor of 1 1 001 to value alphanumerical channel four character label using 7 bit ASCII origin with no parity Bits 55 63 71 79 0 alphanumerical channel four character label using 7 bit ASCII destination with no parity Bits 87 95 103 111 0 local sample address 32 bit binary number representing the sample count of the first sample of the channel status block time of day code 32 bit binary number representing time of source encoding in samples since midnight reliability flags 0 data in byte range is reliable 1 data in byte range is unreliable 00000000 not implemented X error check code for bits 0 183 390 ATS 2 User s Manual Serial Interface Measurements Appendix B The Digital Audio Signal Serial Interface Measurements ATS 2 provides tools to examine and test both the embedded audio sig nal and the serial interface signal ATS monitors and analyzes the embedded digital audio signal using in struments in the Analyzer panel such as the Audio Analyzer the Spec trum Analyzer the Multitone Audio Analyzer and the Harmonic Distortion Analyzer Many interface related proble
112. or Hz are discussed in more detail in the relevant sections on amplitude or frequency units Relative Units dBg decibels relative to the Analog Generator amplitude setting dBr decibels relative to a user defined reference The generators and the analyzer have separate independent dBr or dBr A dBr B fields in the References area of their respective panels You can manually enter dBr values from the keyboard or you can capture current ATS values for cer tain Reference fields as follows m Analog Generator dBr Function Key F3 or Edit Menu command Set Generator dBr Ref ATS 2 User s Manual Frequency Units Appendix A Units of Measurement m Analyzer dBr Function Key F4 or Edit Menu command Set Analyzer dBr Ref dBrInv decibels relative to a user defined reference inverted This is exactly as described under dBr just above but plotted upside down so that smaller or negative values are at the top of the graph and larger or positive values are at the bottom The dBrInv units are commonly used in conjunction with Regulation mode such as when measuring frequency response of a pre emphasized broadcast transmitter Inverted plotting of the generator levels required to produce constant modulation percentages produces the expected shape of the transmitter frequency response Frequency Units Hz hertz This is the basic frequency unit expressing the number of cy cles of a signal in one second The rest of the frequ
113. origin data 65 66 67 68 69 Alphanumeric channel origin data last character 73 74 75 76 77 Alphanumeric channel destination data first character 81 82 83 84 85 Alphanumeric channel destination data 90 91 92 Alphanumeric channel destination data 97 98 99 100 101 Alphanumeric channel destination data last character bit 104 105 106 107 108 109 Local sample address code 32 bit binary LSW bit 112 114 115 116 117 Local sample address code 32 bit binary bit 120 122 123 124 125 Local sample address code 32 bit binary bit 128 130 131 132 133 Local sample address code 32 bit binary MSW bit 136 138 139 140 141 142 Time of day code 32 bit binary LSW bit 144 146 147 148 149 Time of day code 32 bit binary bit 152 154 155 156 157 Time of day code 32 bit binary bit 160 162 163 164 165 Time of day code 32 bit binary MSW bit 168 170 171 172 173 reserved Reliability flags bit 176 177 178 179 180 181 182 183 Cyclic redundancy check character CRCC bit 184 185 186 187 188 189 190 191 388 ATS 2 User s Manual The Serial Digital Interface Signal Appendix B The Digital Audio Signal Professional format channel status field interpretations pro con 0 consumer 1 professional format BB non audio 0 audio data is linear PCM samples or more accurately 1 other than linear PCM samples not linear PCM emphasis 000 Emphasis not indicated 100 No emphasis 110 CD type emphasis 111 J 17 emphasis
114. pass and low pass filter selections are not available for the Phase function ATS 2 User s Manual 139 Chapter 10 The Audio Analyzer The Function Meters 140 180 180 deg 0 360 deg 90 270 deg Auto reading without sweep om Auto when swept and graphed gt 540 360 180 360 540 Figure 116 Audio Analyzer phase display modes Function Meter Units As with the Level meters the units available for the Function meters de pend upon whether the Analyzer Input is set to Digital or Analog The measurement function you choose for the Function meters will change the unit options as well m In the amplitude measurement functions Amplitude THD N Amplitude and Bandpass the analog input and digital input units and their references are exactly as described above under Level Meter Units on page 126 m In the various ratio measurement functions 2 Channel Ratio Crosstalk THD N Ratio and SMPTE IMD the available units are dB and X Y independent of whether Analog or Digital input is selected m In Phase function the only unit available is degrees For an explanation of the units of measurement used in ATS and the ref erences for the relative units go to Units of Measurement Chapter 1 Function Meter Ranging Like the Level meters the Function meters have a set of amplitude ranging controls which are located lower on the Audio Analyzer panel be nea
115. pattern is a special view of the interface waveform which gives a quick estimation of the quality of the signal With conventional oscilloscopes the eye pattern is created by setting the horizontal sweep to about one UI triggered at the cell rate 2 UI The per sistence of the screen phosphors or the storage capabilities of the scope display an overlay of hundreds or thousands of data cells This produces a one cell wide display with a shape like an eye The in side of the eye is reduced horizontally by jitter which moves the left and right sides of the eye in and out the eye is reduced vertically by noise which moves the top and bottom of the eye up and down or by reduced signal level bandwidth reductions tip the leading or trailing sections of the eye opening The Digital Interface Analyzer collects a long series of data cells about 120 000 at a 48 kHz sample rate and produces a graphic display equiva lent to the inside of an eye pattern on an oscilloscope AESS specifies a minimum eye opening of 200 mV vertically by 0 5 UI horizontally The AES3 minimum can be superimposed as a reference on the eye pattern display by entering these values into a Limit file The file 48kAES3 Eye Pattern atsl is provided as a sample of such a Limit file On the Digital Interface Analyzer panel Wave Display must be set to Eye Pattern 192 ATS 2 User s Manual Digital Interface Analyzer Waveform Views Chapter 12 The Digital Interface Analyz
116. perform DSP calculations on the data before display These are called batch mode measurements since the data is acquired and processed in discrete batches In batch mode there is always an initial ac quisition after which the data is in memory and different analyses can be performed Analyzer instruments which use FFT techniques including the Spectrum Analyzer the Digital Interface Analyzer and the Multitone Audio Analyzer are all batch mode instruments The Analyzer Instruments Figure 11 Analyzer ATS Analyzer instrument selection Instrument Audio Analyzer hi Ch A Pet udio Analyzer FFT Spectrum Analyzer INTE RYO Digital Interface Analyzer FASTTEST Multitone Audio Analyzer Harmonic Distortion Analyzer A Range cd A The Analyzer panel provides access to several specialized analysis tools called instruments Selecting an Analyzer instrument loads a specific mea surement program into the Analyzer DSPs Each Analyzer instrument changes the appearance of the Analyzer panel bringing its own set of in put setting reading and other parameter choices The Analyzer instruments are discussed individually in subsequent chap ters They are m The Audio Analyzer Chapter 10 ATS 2 User s Manual 43 Chapter 5 Signal Analysis with ATS 2 Sweeps and Graphs m The Spectrum Analyzer Chapter 11 m The Digital Interface Analyzer Chapter 12 m The Multitone Analyzer Chapter 13 m The Harmonic Distortion Ana
117. preferences are made on the panel all the results are displayed on the Graph panel in conjunction with settings on the Sweep panel ATS 2 User s Manual 189 Chapter 12 The Digital Interface Analyzer The Digital Interface Analyzer panel Data 1 Data 1 Data 1 Data 1 Intervu Jitter sec Intervu Intervu Intervu Lower Intervu Jitter Ul Probability Amplitude Eye Opening Data 3 Intervu Upper Eye Opening al Interface o Amplitude mE Histogram a Z g gt Jitter Interface Rate Interface 0 Spectrum Histogram Spectrum e y One 5 a gt ig l Interface Jitter Bit Width Interface Eye 2 Waveform Waveform Pattern E Histogram 32 o 3 ae a Jitter E Histogram 55 O J n gt g Figure 151 Sweep panel selections for the Digital Interface Analyzer views 190 ATS 2 User s Manual Digital Interface Analyzer Waveform Views Chapter 12 The Digital Interface Analyzer Later in this chapter we will look at the Digital Interface Analyzer panel in detail but first we will look at the Sweep panel settings necessary to cre ate the nine basic Digital Interface Analyzer views The chart in Figure 151 shows the nine views and the Sweep Source 1 and Data 1 and Data 3 for Eye Pattern settings which define the views Also see InterVuMenu atsb on page 201 InterVuMenu atsb is a macro that makes the Digital Interface Analyzer setup a one click process combin ing a graphical menu interface with automated s
118. provided on the Audio Precision Resources Disc and are also available for download from our Web site at ap com Audio Precision provides a utility program called FDP as a download from our Web site at as an aid to creating your own downloadable filters Several Matlab functions are also available on the Audio Precision Re sources Disc and on the Web site which will be helpful to Matlab users in creating properly formatted downloadable filter files use with ATS See Ap pendix D for more information 148 ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer Bandpass Bandreject Filter Tuning Figure 123 The Audio Analyzer 0 00282 Function 0 00282 BP BR Filter Selections Measurement Function Crosstalk Range lv Det Auto E BPYBR Fltr Freg E Counter Tune a Counter Tuned Sweep Track References Gen Track dBra 387 3 rr der B D Gen Track Fixed Freq 1 00000 kHz WF SAT y ufatts 8 000 Ohm dBmJen0 0 Ohms The BP BR Fitr Freq bandpass bandreject filter frequency controls af fect only the Function meters and only in certain functions as listed be low The filter does not affect the Level meter or Freq counter readings The bandpass filter is a highly selective filter of approximately 1 13 oc tave bandwidth Q 19 giving a 3 dB bandwidth of 5 2 of the center frequency The filter is tunable across the audio spectrum from 0 04 to 42 of the sa
119. require longer times to acquire and transform the signal Auto is the recommended selection The Auto selection automatically sets the acquisition buffer and transform length to be exactly twice the ATS 2 User s Manual 227 Chapter 13 The Multitone Audio Analyzer Processing 228 length of the arbitrary waveform presently loaded into the generator This condition is essential for the Noise measurement function of the Multitone Audio Analyzer and will also work well with any other Multitone test One of the seven fixed FFT lenaths can also be selected For Multitone to provide useful results a selected fixed FFT length must be an integral multiple of the multitone waveform length See Appendix C for more infor mation on transform length for synchronous FFTs Processing Figure 193 Multitone Processing Processing Synchronous S el ecti ons i 5 uF chronous E Triggering Freq Corrected Windowed The Processing choices for the Multitone Audio Analyzer are Synchronous Freq Corrected Windowed Synchronous is the normal selection Synchronous processing uses no window function and assumes that the generator tones are synchro nous with the FFT length Freq Corrected is also a synchronous selection but similar to the None move to bin center selection in the FFT Analyzer this choice first corrects the frequency of the received signal by up to 4 in an attempt to make the generator tones and the FFT length synch
120. results with a powerful graphing engine ATS 2 offers control over instrument regulation and over sweep settling parameters Pass fail limits or equalization data can be attached to a sweep to constrain a particular measurement A variety of computations can be performed on the measured data after acquisition Sweep tests can be saved and recalled and ATS 2 measurements can be automated by macros written in the AP Basic programming language m ATS 2 can examine the digital interface signal and perform elemental analysis of digital communication paths and assure the integrity of digitally transmitted data ATS 2 can extract a variety of statistics from the digital waveform such as the actual sample rate the interface waveform voltage the active and inactive data bits and flag bits ATS 2 can measure the jitter in the interface signal ATS 2 also has the capability of transmitting and receiving the full complement of status bits for both the AES3 professional and IEC60958 3 consumer digital audio interface signals m ATS 2 s sample rate may be synchronized to an external AES signal a squarewave or an NTSC PAL video source ATS 2 User s Manual 3 Chapter 1 Introduction A STAGE ars BW ANALOG gt i STAGE A TRIGGER INPUT UTILITY INPUT UTILITY INPUT BUFFERS DIGITAL INPUTS C SYNC REF INPUT Conceptual Architecture of ATS 2 m The ATS 2 Performance Upgrade Option adds more power a pair of
121. rms This unit is used only on the Analog Generator and Digital Generator panels and this setting accurately calibrates the genera tor output in Vrms when a sinewave is being generated When using other waveforms such as noise squarewaves multitone IMD test signals and so on with Vrms the signal has the same peak to peak voltage as a sinewave at that setting as shown in Figure 285 For the analog outputs Vrms is an open circuit value and the actual output voltage will be less with a load GENERATOR AMPLITUDE SETTING 1 000 V 0 dBV IN ALL CASES SIGNAL AMPLITUDE 2 828 Vpp IN ALL CASES 2 828 Vpp SINEWAVE SQUAREWAVE 500 Hz 3 kHz 1 1 RATIO rms AMPLITUDE rms AMPLITUDE IMD TEST SIGNAL 1 000 V 0 dBV 1 414 V 3 01 dBV rms AMPLITUDE 0 707 V 3 01 dBV Figure 285 ATS 2 generator output calibrations Vp volts peak This unit is used on the output setting fields on the An alog Generator and Digital Generator panels and on the Peak Mon me ters on the Analog Input panel This calibration assumes a sinewave and is arithmetically scaled to the Vrms value by V2 approximately 1 414 Since non sinusoidal waveforms are calibrated to have the same peak to peak value as a sinewave the Vp unit should be correct for most non sinusoidal waveforms When used with the Analog Generator Vp is an open circuit value and the actual output voltage will be less with a load Vpp volts peak to peak This unit is used on the output settin
122. sections can be examined by typing fil ters 1 sos at the prompt ATS 2 User s Manual 407 Appendix D User Downloadable Filters MATLAB Downloadable Filter Support 408 ATS 2 User s Manual Appendix E AP Waveform File Support Audio Precision waveform files aam aas agm ags are of propri etary format These files can be created in the ATS environment and saved on disk using the File Menu Saved files can be opened for insertion in the acquistion buffer the transform buffer or either the analog or digital gener ator arbitrary waveform buffers This chapter discusses additional support for working with Audio Preci sion waveform files You can export to and import from standard WAV files and MATLAB users are provided with functions to write read and equalize arbitrary waveforms that are in the Audio Precision format Exporting to WAV The Export WAV File selection provides the capability to export audio data to disk as a Microsoft Windows PCM WAV file from one of three 2700 Series instrument memory buffers the Arbitrary Waveform buffer the Acquisition buffer or the Transform buffer Operation From the Main menu select File gt Export gt wav File You will be presented with the File Save dialog Enter a file name and browse to the folder where you would like create the WAV file Click Save to continue In a few moments you will be presented with the Export MS wav Waveform dialog In the Ins
123. signal coupling in ATS 2 m For signals in the analog domain capacitors can be switched in and out of the input circuits to block or pass DC When Analog is selected as the Audio Analyzer Input AC or DC coupling is controlled from the Analog Input panel as explained in Chapter 4 For signals in the digital domain blocking or passing DC is accomplished in DSP When Digital is selected as the Audio Analyzer Input DSP AC or DC coupling is controlled from the Audio Analyzer panel as explained below This selectable coupling affects the readings shown on the Audio Analyzer Level and Frequency meters the Function meters as you will see below always have a high pass filter implemented effectively blocking DC to the various Function readings under all circumstances Also refer to the block diagram in Figure 101 Figure 106 8 Analyzer Dl x The Audio Analyzer Level Meters aa Audio Analyzer gt Coupling Options Digital Input Only ChA Input biga E ChB lv DC DEM With Input set to Digital the selections on the Audio Analyzer panel operate as follows ATS 2 User s Manual 127 Chapter 10 The Audio Analyzer The Frequency Meters m When the check box for either channel is unchecked DC is blocked in DSP for that channel m When the check box for either channel is checked DC is passed for that channel Common Mode Testing and Coupling Issues When making common mode tests small DC offsets from the DUT can resu
124. signals normal dither 256x synchronous averaging triggered from digital generator Figure 139 is the same signal with 256x synchronous averaging trig gered from the digital generator The sinusoidal waveform is now clearly visible Signal Alignment for Synchronous Averaging In order for the amplitude of coherent signals to be preserved during syn chronous averaging each new acquisition must be accurately time aligned with the previous acquisitions before it is added to the accumulating signal in DSP memory For some signals time alignment may be accomplished by proper triggering at acquisition Other signals may require a DSP re alignment process Also see Triggering with Synchronous Aver aging on page 181 Because of the frequency shifting that occurs using the None move to bin center Spectrum Analyzer Window selection the synchronous averag ing choices change with the FFT windowing mode For all FFT Window se lections except None move to bin center the synchronous choices are Sync re align and m Sync If None move to bin center is selected as the FFT Window there are four synchronous choices Sync re align move center first m Sync re align average first Sync move center first and m Sync average first ATS 2 User s Manual 169 Chapter 11 The Spectrum Analyzer Averaging 170 Sync without re align When you are confident that nature of the signal and the triggering selec tions on the Spec
125. sion Web site at ap com Online Help While you are running ATS you will have much of the information con tained in the ATS 2 User s Manual available to you instantly in the online Help system included as part of the ATS 2 system You can access the Help system while you are using ATS in a couple of ways m On the Menu bar click Help The Help menu offers commands to search the Help Index browse through the Help Topics or select an alternate Help library AP Basic Lanquage m ATS also has context sensitive Help available Almost every control and display on each software panel has a help topic associated with it To view the topic simply click on the field or control then press the F1 function key The AP Basic User s Guide and Language Reference You can create simple or complex test and measurement macros to auto mate ATS 2 using AP Basic the programming language included with the system The same AP Basic language is also used to automate other Audio Precision PC controlled systems and to interface with other programming languages The AP Basic User s Guide and Language Reference is published in elec tronic form as a PDF file available on the Audio Precision Resources Disc and as a download from the Audio Precision Web site at ap com You will also find online Help for AP Basic while running ATS Click Help gt AP Basic Language Help on the Help menu 6 ATS 2 User s Manual GPIB Documentation for ATS 2 Chapter 1
126. test will termi nate An External Sweep test can be manually terminated by pressing the Esc key or clicking on the Stop button when it is apparent that the se quence of test tones has ended but End On can terminate the sweep au tomatically End On follows this logic m if the value set in End On equals the Stop value plus or minus the Spacing percentage the sweep will terminate when the End On value occurs m if the value set in End On does not equal Stop Spacing and is outside the range set by Start and Stop the sweep will terminate when the End On value occurs m if the value set in End On does not equal Stop Spacing and is within the range set by Start and Stop the sweep will terminate on a second occurrence of the End On value This produces several different behaviors m The first case where End On equals Stop Spacing allows you to set End On at the end of your desired sweep The last value acquired Stop Spacing will be graphed m The second case where End On does not equal Stop Spacing and is outside the Start Stop range allows you to set End On beyond your desired sweep You can for example place an out of band cue tone after the swept tones to terminate the sweep m The third case where End On does not equal Stop Spacing and is within the Start Stop range allows you to set End On to a value in the mid range of your desired sweep This accommodates for example a frequency test which sweeps
127. that are non synchro nous this selection modifies the signal so that it becomes synchronous None move to bin center shifts the fundamental frequency of the sig nal to the center of the nearest bin which is the same as stretching or com pressing the waveform so that an integer number of cycles fits exactly in the transform length See Appendix C for a conceptual overview of FFTs including basic information on synchronous FFTs When used with a single sinewave this technique results in excellent se lectivity with the signal spreading to the adjacent FFT bin normally 120 dB down or more Due to the correction the signal in the DSP buffer will now be at an exact bin center and NOT at the original frequency Here s an example assume that you want to test an ADC operating at a 48 00 kHz sample rate using a test signal frequency of 997 Hz This fre quency is often chosen because it is non synchronous with the sample rate and causes the converter under test to be exercised through a large num ber of its possible states With an FFT length of 16 384 samples the two nearest synchronous fre quencies are 996 09375 Hz exactly 340 cycles in the buffer and 999 0234375 Hz exactly 341 cycles The None move to bin center mode of the FFT program will shift the frequency of the acquired 997 Hz signal in DSP memory down to 996 09375 Hz the nearest synchronous frequency and then perform a windowless FFT The result the ADC under test was
128. the Analog Input panel to the Spectrum Analyzer Channel A input and the jitter signal from the DIO to the Channel B input The only difference between the two choices are the units selected for the jitter measurements unit intervals UI or seconds Digital signals are applied directly to the Spectrum Analyzer DSP ana log signals are first digitized by precision ADCs selected on the Analog In put panel before being applied to the Spectrum Analyzer To configure analog input connectors range coupling select ADCs bandwidth and so on go to the Analog Input panel see Chapter 6 To configure digital input connectors digital input format and other aspects of the interface go to the DIO panel see Chapter 7 Peak Level Monitors Figure 130 ATS Spectrum Analyzer peak ESS mal level meters Instrument FFT Spectrum Analyzer Ch A Input Digital a Ch B oo rs res Mon oo Frs The two Peak Mon meters on the Spectrum Analyzer panel continu ously display the peak amplitude of the digital signal as it is presented to the Spectrum Analyzer Only digital domain units FFS dBFS FS or bits are available for these meters The primary purpose of the peak monitors is to avoid overload of the in put analog to digital converters ADCs When signal is being acquired from the analog source and Auto Range is in use on the Analog Input panel ADC overload should never be a problem If any of the Analog In put range contr
129. the instability of the mea sured parameter is consistently greater than the Tolerance value entered on the Settling panel and that it is impossible to satisfy the Settling algo rithm and get a settled reading The Timeout control exists to keep your sweep from running slowly or even locking up under these conditions If a settled reading cannot be made within the period of time entered in the Timeout field ATS will cal culate the average value of the last 6 measurements enter that value as a data point and move on to the next sweep step ATS 2 User s Manual 283 Chapter 15 Sweeps and Sweep Settling Timeout The default Timeout value per step is 4 000 s Timed out points are marked with a white T at the top of the graph above the plotted point In the Data table each timed out point is indi cated with the letter T following the data The Log File can also indicate timed out data with several notices See The Log File page 364 284 ATS 2 User s Manual Chapter 16 Graphs The graph is a central feature of the ATS 2 test and measurement sys tem As mentioned in Chapter 15 the functions of the Graph panel and the Sweep panel are closely related To configure and initiate any measurement to be plotted on a graph you must go first to the instrument panels and then to the Sweep panel Whether real time Analyzer measurements or batch mode FFT measure ments the Sweep panel is the control center Besides coll
130. the signal negative peak value and the other at the positive peak value If the interface signal pulse top and bottom are clean and level no tilt or aberrations the spikes will be narrow and of high probability values Slower rise and fall times cause each spike to broaden in the direction of zero volts Normal mode noise causes broadening of each spike to both lower and higher amplitude values If these impairments are severe enough the two spikes will merge into a low probability lump spread across the peak to peak voltage range of the signal i Figure 157 Digital Interface Analyzer interface signal amplitude probability 5 Vpp signal ATS 2 User s Manual 197 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Histograms 198 As indicated in Figure 151 this view requires these Sweep settings Source 1 Intervu Amplitude Prob and m Data 1 Intervu Probability Source 1 range should be about 5 V a Data 1 range of 0 to about 20 on a linear scale is useful for this view Interface Pulse Width Histogram The interface pulse width histogram view displays the probability of vari ous values of width for interface signal pulses With no impairment of the interface signal the resulting histogram will consist essentially of three vertical spikes at the 1 UI 2 UI and 3 UI points on the horizontal axis The height of each UI spike shows the probability of pulse widths of that value occurring For ty
131. tivity and in potential amplitude measurement error The Hamming and Hann windows for example have the best selectiv ity near the top of the window but limited rejection of signals more distant from the center The Blackman Harris Equiripple and Rife Vincent win dows have much better rejection of more distant signals The Flat Top win dow has the poorest selectivity but virtually no amplitude error across the center three bins See Figures 134 and 135 for comparison of the close in selectivity curves of the Spectrum Analyzer FFT windowing choices The window function is applied after signal acquisition and before the transform which means that you can change the FFT Window selection and re transform the data using the F6 command without making another acquisition You can compare the effects of several different window func tions on the same signal acquisition by checking the Append box on the Sweep panel and using F6 to re transform the data with new window set tings pm Audio Precision FLAT TOP WINDOW BLACKMAN HARRIS WINDOW EQUIRIPPLE e WINDOW 120 140 160 1 05k Figure 134 FFT Window Functions Flat Top Hann Blackman Harris and Equiripple ATS 2 User s Manual Spectrum Analyzer Window Selection Chapter 11 The Spectrum Analyzer E Audio Precision HAMMING WINDOW GAUSSIAN EQUIRIPPLE WINDOW WINDOW RIFE VINCENT ig NOW 4 WINDOW Figure 135 FFT Window Functions
132. to 1 unit interval The dB UI provides a logarith mic time unit scaled to the interface signal and is primarily used for FFT plots of jitter amplitude ATS 2 User s Manual DCX 127 Units Appendix A Units of Measurement DCX 127 Units The DCX 127 Multifunction Module brings additional measurement ca pabilities to ATS 2 and with these features come additional units of mea surement DCX 127 Amplitude Units Vdc volts dc This is the basic unit of direct current dc electromotive force f V f of V is a value which is a function of voltage f V is computed from f V V offset x scale See DMM Offset and Scale Values on page DCX 127 Resistance Units Ohms ohms This the basic unit of electrical resistance also shown by the symbol Q f O f of O is a value which is a function of resistance f O is com puted from f O ohms offset x scale See DMM Offset and Scale Values on page DCX 127 Digital Input and Output Units dec decimal The decimal unit converts the DCX 127 digital input and output between binary and decimal representation hex hexadecimal The hexadecimal unit converts the DCX 127 digital input and output between binary and hexadecimal representation oct octal The octal unit converts the DCX 127 digital input and out put between binary and octal representation g x input Like the scaled voltage and resistance units g x enables you to scale digital in
133. ues 40 ATS 2 User s Manual Signal Analysis with ATS 2 This chapter gives a brief overview of the tools ATS 2 provides for signal analysis and serves as an introduction to test and measurement techniques using ATS 2 ATS 2 can test and measure analog audio signals the serial digital interface signal and the digital audio signal carried on the interface For each type of signal ATS 2 provides the capability to generate a vari ety of stimulus signals for input to the device under test DUT and the ca pability to analyze the output of the DUT in a number of different ways References link the key topics introduced here to later chapters where they are examined in detail Analog Audio Signals Analog Audio Generation and Output ATS 2 can produce a wide range of analog audio signals in the Analog Generator see Chapter 8 to be applied to the input of an analog DUT as stimulus signals The Analog Generator panel also provides controls to select and config ure the analog outputs The Analog Generator and the Digital Generator discussed below are similar in appearance and function Analog Audio Input The ATS Analog Input panel provides the means to select and configure the analog inputs The signals routed through the Analog Input panel are then converted to digital audio signals for analysis using high perfor mance analog to digital converters ADCs After conversion the signals ATS 2 User s Manual 41 Cha
134. unbalanced connectors for both A and B channels are routed to the ATS 2 analog inputs See Chapter 4 Signal Inputs and Outputs for more information about the ATS 2 inputs and outputs and the software panels associated with them Refer to the manual Getting Started with ATS 2 for detailed in put and output specifications The ATS 2 Rear Panel The only switch on the ATS 2 hardware is the mains power switch The power switch is located on the left side of the rear panel in the power entry module which also contains the power cord connector the mains voltage selector and the power fuse s The ATS 2 monitor and headphone sync ref trigger auxiliary control and APIB connections are also mounted on the rear panel 32 ATS 2 User s Manual The ATS 2 Rear Panel Chapter 3 The ATS 2 Hardware Fuse Holder Power Mains Supply Mains Voltage Reserved for Monitor Switch Voltage Jumper Indicator GPIB Panel Sync Refin Outputs TrigIn_ Trig Out ZL Power Fuse Power S N Option APIB Auxiliary Cord Replacement Entry Label Headphone Auxiliary Control In Ground Connector Information Module Jack Control Out Connector Figure 7 ATS 2 Rear Panel POWER ENTRY MODULE this module includes the e POWER SWITCH This switch turns the main power supply to the ATS 2 hardware ON I or OFF O To assure stable operation after ATS 2 is switched off or loses power wait 15 seconds before re applying power e POWER C
135. waveforms simultaneously See Chapter 8 for more information on the Analog Generator Signals for Digital Measurements The Digital Generator creates audio signals in DSP that are then embed ded in a digital audio interface data stream such as described in the AES3 or IEC60958 standards This interface signal is configured for output by set ATS 2 User s Manual 99 Chapter 9 The Digital Generator The Digital Generator Panel tings made in the Digital Input Output DIO panel which is discussed in detail in Chapter 7 See Appendix B for more information on the digital au dio signal The Digital Generator Panel Open the Digital Generator panel by choosing Panels gt Digital Gen inn erator by clicking the Digital Generator button on the Panel toolbar or by the keyboard shortcut Ctrl D Like most ATS panels the Digital Gen erator can be viewed in two sizes Double click the panel Title Bar to change sizes Figure 70 The Digital Generator Panel i Digital Generator O x af fra Sine Normal Frequency Ch A q y 357001 kHz en Isis EQ Curve wa Ens Em zj Dither Type Triangular X References Volts FS fi 000 Freq 397000 kHz dBr 387 3 mFFS The Digital Generator panel is divided into three areas ret FFS ail Amplitude ee m The upper area which provides fields for choosing waveforms setting amplitude and attaching EQ curves m the center area which offers cont
136. which allow you to navigate lists of options search for a file by browsing through a hierarchy of folders and so on Browser buttons are identified by the ellipsis mark cua Outputs Grr cae m Custom buttons that control special functions such as GO ON OFF 1 0 and so on m Sliders with which you can continuously adjust a value Sliders are found on the Volume toolbar and on Bar Graph panels Sliders can be operated by either the mouse pointer or by using the arrow keys Panel Readings Results of tests or measurements are called readings which ATS can dis play in several ways as Phase 0 02 deg a m Reading fields sometimes called measurement fields or meters Reading fields come in two variations with and without a drop down list to select units See Appendix A Units of Measurement Reading fields always display green text or numbers on a black field m Bar graphs which display values as a continuous colored bar like a conventional analog meter lock coding m Status indicators which show the presence or absence of a condition by a small colored rectanale 12 ATS 2 User s Manual The ATS Menus Chapter 2 The ATS Control Software The ATS Menus The ATS Menu bar extends across the top of the ATS window and is al ways visible In this chapter we will take a brief tour of some of the ATS menus Details of menu options controls and submenus will be explored in the chapters discussing specific AT
137. which are the components of a squarewave FFT Record Looping The mathematics of FFT processing see the record as an endless loop of signal just as if the end of the record was spliced to the beginning of the record C Figure 291 Truncation of non synchronous waveform In audio editing if there is any difference in the value or slope of the sig nal at the moment of the splice there will be a discontinuity or jump in the waveform at that point An audio edit will pop or click at such a dis continuity The same thing happens in FFT processing the discontinuity like an audio pop contains a great deal of energy spread widely over the frequency spectrum This energy swamps all but the largest signal peaks and produces a useless set of results and a characteristic spectrum Figure 292 shows an FFT of a 100 Hz sinewave with a discontinuity in the record loop Without a way to deal with loop discontinuities almost all FFTs would look something like this ATS 2 User s Manual FFT Windowing 20 50 100 200 500 1k 2k 5k 10k 20k 20k Hz Figure 292 Non synchronous FFT with no windowing function 100 Hz sinewave Two techniques have been developed to solve this problem One is FFT windowing the other is the use of synchronous FFTs FFT Windowing Let s return briefly to the audio editing example The click caused by an abrupt transition can usually be eliminated by making the transition grad ual with a ra
138. within the Graph panel can be adjusted for size You can zoom in or magnify any area of the graph by dragging the mouse pointer diagonally across the area you would like to magnify Dragging the mouse pointer will draw a rectangle surrounding the area as The Graph Options Menu Chapter 16 Graphs shown in Figure 224 When you release the mouse button the graph will re size itself to the rectangle you have drawn You can perform this opera tion repeatedly to zoom further and further in When you are zooming into graphs of batch mode measurements the Sweep Reprocess Data Ctrl F6 command is normally sent to the Ana lyzer requesting new data at the new sizing so that the zoomed view will consist of the maximum possible resolution This automatic reprocessing can be disabled on the Configuration panel by unclicking Reprocess FFT data on zoom The Sweep Reprocess Data command is only effective if the acquired signal is still in the DSP memory A test file loaded from disk for example will only contain the Graph data of the FFT being viewed when the test was saved and increasing the resolution during a zoom is not possible The Graph Options Menu Click the right mouse button anywhere within the graph itself and the Graph Options menu will appear at the mouse pointer This menu pro vides graph display and control options as shown in Figure 225 Figure 225 Graph Options menu Mew Data Zoomaut oomout to Origina
139. 1 ATS 2 User s Manual The Digital Input Chapter 4 Signal Inputs and Outputs We recommend that you do not use the balanced and unbalanced digital outputs simultaneously Circuit conditions external to ATS 2 could degrade the system performance However the optical output can be used simultaneously with either the balanced or unbalanced digital output The Digital Input The digital input accommodates the same interface formats as the digi tal output The XLR female connectors provide a balanced input for satisfy ing the electrical requirements of an AES3 professional format digital audio signal in either single or dual connector configurations Use the connector labeled I for the customary single connector configuration and both I and Il for the optional dual connector configuration Input termination can be set on the DIO panel to HiZ approximately 10 kQ or to 110 Q the AES3 standard The BNC input connector is configured for an unbalanced digital signal satisfying the electrical requirements of both the AES3id professional for mat and the IEC60958 3 S PDIF consumer interface format Input termi nation can be set on the DIO panel to HiZ approximately 10 kQ or to 75 Q The optical input is compatible with the Toslink interface Digital input selection and interface configuration are set on the DIO panel page 51 We recommend that you do not maintain connections to the balanced and unbalanced digital
140. 1 Tolerance setting The Flat algorithm guarantees that the signal transients have been set tled to the specified Tolerance for some time This tends to take longer than the Exponential algorithm Average Settling Algorithm The Average settling algorithm takes the mathematical average of the number of consecutive measurements entered in the Points field and re ports the result as a data point The Average algorithm is particularly useful when the signal is fundamentally noisy and might never settle within a practical tolerance Settling Tolerance Settling Tolerance represents the amount of variability you are willing to accept from test to test A tolerance of 0 1 about 0 01 dB may be ap propriate for frequency response tests on a DUT with excellent characteris tics at the other extreme tolerances of 10 to 25 may be necessary to obtain data under noisy conditions The default value is 1 Settling Floor When working near the very bottom of the dynamic range for a particu lar ATS instrument the difference between two adjacent values or quantization levels can be large compared to the criteria in the settling algo ATS 2 User s Manual rithm At levels greater than a few percent of full scale on the instrument the value set in the Tolerance field is normally the determining parameter but close to the bottom of a measurable range another technique is needed to keep the settling from slowing down the sweep or even stopp
141. 1 or Source 2 fields of the Sweep panel m When AGen Track is selected the filter tracks the frequency of the Analog Generator This mode is useful for testing ADCs driven from ATS 2 s analog output m When DGen Track is selected the filter will automatically track the frequency of the Digital Generator This mode is normally used when sweeping input to output through a digital device with the stimulus tone coming from ATS 2 s Digital Generator m When Fixed is selected the field immediately below which is grayed out in other modes becomes active The filter will be set at the frequency entered in this field It is also possible to vary the filter frequency in this mode as part of a sweep test Although this is similar to the Sweep Track choice above in this case the filter can be swept independent of generator frequency To sweep the filter frequency during a test first be sure you have selected Fixed in the BP BR Filter Freq field here on the Analyzer panel Fitr Selecting Harmonics in Bandpass In Bandpass function the Fltr field offers the selections of Narrow Narrow Freq x2 Narrow Freq x3 Narrow Freq x4 and Narrow Freq x5 150 ATS 2 User s Manual References Chapter 10 The Audio Analyzer Figure 124 The Audio Analyzer E Functior Ea Narrow Fltr harmonic selections Measurement Function Bandpass v Range I zj Det Auto JRE a BP BR Fltr Freg Bu lt 10 Hz Fsi2 Sweep Tra
142. 16384 samples the frequency resolution has doubled to 2 93 Hz The effect of this is that any tone or product of a tone from the orig inal 8192 sample long multitone must fall only into alternate bins in the FFT the even bins that are 5 86 Hz apart The in between or odd bins shown in light gray in Figure 186 contain only noise The result at each sweep step is twice the rss sum of the noise power in the odd bins between that sweep step and the step below it A response curve the dark line in Figure 186 is drawn through these results for display Why TWICE the rss sum To take into account the unmeasured noise power in the skipped even bins in each measurement segment The ATS Noise Multitone Measurement selection provides a noise vs frequency curve as shown in Figure 187 100 200 Figure 187 Typical Multitone Noise measurement In a DUT with no distortion a Multitone Distortion measurement and a Noise measurement will provide essentially the same results ATS 2 User s Manual 223 Chapter 13 The Multitone Audio Analyzer Multitone Measurements Masking Curve Figure 188 Example of a ANEA multitone masking curve analysis Fi F2 F3 F4 F5 F6 F7 F8 CHANNEL A st lc TT R N j F6 F7 F8 In a masking test ATS determines the correct masking curve the shapes of which vary with frequency for every tone to be evaluated at the levels they are received from the DUT The dark lines in the up
143. 263 Plotting Data as X versus Y 2 004 263 Data 3 through Data6 2 2000 264 Sweep Display Mode 2 0050 88 ee 265 Go Stop Pause ioocipaorasoco oro erase 266 Repeat aaa a 000 a a a a a a a a a 266 Append amp cae coud a a a ewe hee a a ma a 266 AppendingaFile 266 Stereo SweepS 2 002 ee ee ee a 267 Single PointSweeps 2 20500 268 Nested Sweeps using Source2 269 Pre Sweep Delay 2 0000 pee eee eee 269 Pre Sweep DelayandAutoOn 269 TableSweeps 0000 eee eee ee ee 270 ExternalSweeps 2 0 004 ee eee 271 External Sweep Operation 272 Start and StOp aooaa a a a a a a a a a a a a a a a a 273 Spacing oaoa a a a a a a a a a a a a a a a aa 273 ATS 2 User s Manual MINE oo 2 2 eo eee eee ee a ee ee 275 Stal COMRUIES 2 curar Oe ORE Se SE 275 Some HINTS s oirrses rra eee 276 External Stereo Sweep aooaa er a a 277 External Single PointSweeps 277 TIME SWEEDS ss cse rrera e traera Ces eas 277 Sweep Settling Bere bee ee Pewee ee Be ee Se Be 278 The Settling Panel spero ow we oe Bee ee 279 Settling Concepts be ea Owe ae ewe ew AR 280 Settling Delay TIMO naaa 280 Algorithm Selection oc cd ee oe Bees oe Gea eee we ES 280 Exponential Settling Algorithm 281 Flat Settling Algorithm
144. 4 Working with Files and ATS 25 Test Files 2 00 0 ee ee ee eee 25 Macro Files 00 0 eee eee ee ee eee 25 Data Files 20 00 eee ee eee 26 Waveform Files 050 epee ee eae 26 Sample Files 00200 eee eee eae 27 The LogFile 02 002 eee eee 27 Keyboard Shortcuts 2 5 580 58a 27 Function Keys 27 ATS2andGPIB 0 002 ee ee eee eee 29 Chapter 3 The ATS 2 Hardware 31 The ATS 2 Front Panel 2 00200 31 The ATS 2 Rear Panel 2 20052 32 Power Recycle Time 2 2 505 804 34 Chapter 4 Signal Inputs and Outputs 35 The Analog Outputs 2 200508 36 The Analog Inputs 0050 eee 37 The Digital Output 38 The Digital Input 39 Electrical vs Data Characteristics Across Formats 39 Chapter 5 Signal Analysis With ATS 2 41 Analog Audio Signals 41 Analog Audio Generation and Output 41 Analog Audio Input 41 Digital Audio Signals 42 The Serial Digital Interface Signal 42 Digital Audio Generation 42 The Analyzer 0 0 000 ee a ee ee 42 Real Time and Batch Mode Measurements 43 ATS 2 User s Manual The An
145. 7 Equalize Compute algorithm 326 Equiripple FFT window Digital Interface Analyzer 208 Spectrum Analyzer 164 Errors logging 314 Export acquistion to WAV file 409 co a ke ak we ee ERA Ee a 334 External sweep 271 end on Lo 274 single point 277 spacing 273 start and Stop 273 start on rules 275 SLOT muss esa A A 277 External sweeps SOUrCE 1 y ga eae he ae da 271 External vs internalsweeps 271 Eye pattern Digital Data Anlyzer 192 E Fast RMS detector see detector function meter 142 Fasttest Multitone Audio Analyzer 213 FFT acquisition 157 394 FFT acquisition length 160 FFT acquisition record 159 394 FFTbDandW IdAth 394 FFT bin width 395 FFT commands 158 FFT display processing 173 Digital Interface Analyzer 202 Spectrum Analyzer 157 FFT graphing 400 FFT record looping 396 434 FFT Specturm Analyzer Spectrum Analyzer 155 FFT start time 177 FFT transform record 161 FFT transforming 157 FFT trigger delay time 180 FFT trigger slope 180 FFT triggering 177 FFT triggering with quasi AC
146. 8 Harmonic Distortion Product Amplitude 248 Harmonic Order Control 249 Distortion Product Bandwidth Limitations 249 Amplitude Units 220004 250 ATS 2 User s Manual RETEPENCES heen teen eb eeeRaeE KG aew ee ee 251 Steering Control 2 005000 251 High Speed High Accuracy Control 252 Sweeping and Graphing Results 254 Chapter 15 Sweeps and Sweep Settling 255 Introduction Sweeps and Graphs 255 Batch Mode Sweeps 2 02880 4 257 Plan YourSweep 2 005 ee eee ae 257 The Sweep Panel 2 00502 eee 258 Source 000 ee ee ee ee 258 Settings Or Readings 2 005002 259 Selecting a Sweep Source 20 259 Start and Stop Values 260 Source 1 LogorLinScales 260 Sweep Resolution 260 Linear Scale StepS 260 Logarithmic Scale Steps 261 X Axis Divisions 000 a eee ee 261 Dalat sdb ee eee raros 261 Selecting the Data1 Reading 261 Top and Bottom Vvalues 204 262 Data1 LogorLinScales 2 262 Y AXiS Divisions 2 0002 2 ee ee 263 Data LiMItS lt 4 eit e eee be ee eee eee a a eu ees 263 Data k a Ohh eSB E OER OR EEE ee Ewes ED
147. 80 80 so so so 80 00 00 00 00 OO 00 00 00 00 00 Receive 4 AEREA AAA ee Transmit E 03 00 d 006 00 OO OO Of 00 00 OO 06 06 00 00 00 0 00 0 Receive B oa 00 00 00 00 00 00 00 00 00 00 00 00 00 0 1E 10 00 00 00 00 00 00 F Figure 36 The Status Bits panel Transmit Status Bits The left side of the status bits panel has a number of fields to select sta tus bit conditions for the transmitted serial interface signal appearing at the ATS 2 digital output The first three option buttons select whether the settings you make oper ate on Channel A Channel B or both To select the format click Consumer or Professional Since the con sumer and professional formats vary greatly in the status bit fields avail able the choice of format will bring an entirely different set of options to the panel We will look at the Consumer format options first ATS 2 User s Manual 71 Chapter 7 The Digital I O Panel The Status Bits panel Consumer Format Status Bits Figure 37 Transmitting Consumer Format J a Status Bits Digital 1 0 Status Bits SS 2 90 Dont care Dont care With the option buttons and drop down lists shown here you can set any of the consumer format status bit conditions See page 386 for more information about Channel Status and for detailed tables of the consumer format status bit fields and interpretations 72 ATS 2 User s Manual The Status Bits panel Chapter 7 The Digital I O P
148. 9 in wide equipment rack using optional mounting hardware m The ATS measurement software which runs on a personal computer PC and provides all the control display report and automation functions for the ATS 2 system The PC is not provided with ATS 2 With the exception of the mains power switch on the rear panel there are no knobs dials controls readouts meters or switches on the ATS 2 chassis All of the measurement settings and adjustments are made on the PC The ATS control software will run under Microsoft Windows XP Profes sional Service Pack 2 or Microsoft Windows Vista Business Edition 32 bit operating systems APIB The control software communicates with the ATS 2 instrument through the Audio Precision Interface Bus APIB Several options have been pro vided for accessing APIB from your PC including m The USB APIB adapter m The APIB PCI card and cable m The APIB PCI Express card and cable m The APIB PCMCIA card and cable GPIB With Option GPIB hardware installed ATS 2 can also be controlled by the industry standard IEEE 488 2 General Purpose Interface Bus GPIB See page 31 for more information about ATS 2 with GPIB About This Manual You re reading the ATS 2 User s Manual This is the primary operation and reference manual for the Audio Precision ATS 2 audio test and mea surement system We recommend you begin by reading the separate introductory manual Getting Started with ATS 2 which
149. ATS These are substituted with Amplitude mode m Cascade has both Auto Fast and Auto Precise modes for automatic selection of detector reading rate ATS has only one Auto automatic selection mode so it is used for both of these cases m Average Peak and S Peak Peak Equivalent Sine detectors are not supported in ATS These are mapped to RMS Bandwidth Lowpass settings have changed 22 kHz in Cascade is substituted with 20 kHz in ATS Cascade settings for 30 kHz 80 kHz gt 500 kHz are substituted with FS 2 in ATS m Cascade and S2 hardware option filters are not supported in ATS 2 m In the Cascade Analog Analyzer Phase is an independent reading in ATS 2 it is one of the Analyzer measurement modes Since a test can only have one measurement mode tests that use both analog Phase readings and readings from another measurement mode such as THD N Ratio or Amplitude may not be mapped correctly All sweeps and bararaphs in the original test will be examined if any refer to the analog Phase reading the Phase measurement mode will be selected and references to other measurement modes will be ignored This does not apply to the Digital Analyzer case since the implementation used by the Digital Analyzer is the same as that in ATS 2 m The fields and hardware controlling the Monitor Speaker are quite different between products An attempt is made to m
150. ATS 2 source resistance and the resistance of the external load for an accu rate setting you must enter the value of the load resistance in the Refer ences dBm field on the generator panel On the Audio Analyzer panel V is the measured rms voltage and R is the value of the source resistance which you must enter in the References dBm field on that panel If you have the 600 Q impedance option you can select that value on the Ana log Input panel as the input termination impedance 600 Q is the most common circuit impedance value for dBm measurements dBm is rarely the correct choice of units for audio measurements dBm units are often mistakenly chosen when dBu units should be used See the sidebar dBm versus dBu on page 375 dBu decibels relative to 0 7746 V rms This is usually the correct choice of units for audio levels in professional audio equipment and sys tems The dBu is a voltage unit and unlike the dBm is independent of cir cuit impedance When used with the Analog Generator dBu is an open circuit value and the actual output voltage will be less with a load See the sidebar dBm versus dBu on page 375 ATS 2 User s Manual Analog Amplitude Units Appendix A Units of Measurement dBm versus dBu Although still in use the dBm unit of measurement is a legacy from earlier days of audio technology when measuring the audio power transferred in impedance matched circuits was important The dBm is a unit of power referenced
151. ATS Menus Chapter 2 The ATS Control Software The View Menu The View menu allows you to select which workspace page is visible and whether or not the Status bar and any combination of Toolbars are dis played A checkmark next to a View menu listing indicates that the selec tion is visible ATS 2 User s Manual 15 The ATS Menus Chapter 2 The ATS Control Software The Panels Menu The Panels menu shows all the control panels available in the control software Click on a Panel name or on its corresponding Toolbar button to open a panel on the current workspace page Panels can be duplicated on more than one page for convenience Closing a panel does not stop its activity If a generator panel has been set to output a sine wave or an analyzer panel to measure a voltage these activities continue whether or not the panel is visible on any page The panel functions are discussed in detail in these chapters m Analog Generator panel Ctrl G See Chapter 8 16 ATS 2 User s Manual The ATS Menus Chapter 2 The ATS Control Software m Digital Generator panel Ctrl D See Chapter 9 m Analog Input panel Ctrl A See Chapter 6 m Analyzer panel Ctrl Y See Chapter 10 m Sweep panel Ctrl S See Chapter 15 m Graph panel See Chapter 16 m Settling panel See Chapter 15 m DCX panel The DCX 127 is an auxiliary multifunction instrument controlled by the ATS software See the user s manual provided with the DC
152. Acquired Waveform Files As with other ATS tests you can save the setup and results of any Spec trum Analyzer tests as an ats2 test file The acquired waveform in the FFT acquisition buffer however is not saved as part of a test If you want to keep the acquired data record for further analysis you must save it as an aam acquisition mono or aas acquisition stereo acquired waveform file Single channel mono waveforms saved at different times can later be individually loaded into the two channels of the FFT acquisition buffer to become stereo acquisitions for comparison in the time or frequency do mains ATS 2 User s Manual 185 Chapter 11 The Spectrum Analyzer Acquired Waveform Files Saving Acquired Waveforms Figure 147 ATS Spectrum Analyzer ENEE Save Stereo Waveform dialog box an To save an acquisition select the File gt Save As menu command choosing either the Stereo Waveforms aas or Mono Waveforms aam as the file type A stereo acquisition waveform file consists of two waveforms joined to gether into a single file a mono acquisition waveform file contains a single waveform To simultaneously save the waveforms from both acquisition buffer channels A and B select the stereo choice To save only one of the channels select mono The left half of the dialog box defines what will be saved into the first section of a waveform file and the right half defines what will go into the second sect
153. Analyzer ERG LCs ee sos e a oe amp oe ye ae 157 435 Index Limits actions upon failure 314 Attached File Editor 313 attaching a limit file 312 making a limit file 311 overview 310 sweep datalimits 02 2 263 Lin scale sweep Data 262 sweep Source 260 Lin scale SOUrceAd 260 Linear Regulation algorithm 357 Linearity Compute algorithm 321 LOg errorS 4 06 64 as wee 314 Log file Clear 202 20 2 2 248 368 configuration 0 364 VIEW gt a oasa drernen ises Padt 368 Log scale SWeepData 262 sweep Source 261 Logscale Source1 260 Looping FFT record 396 Low bound Regulation parameter 357 Lowpass filter see bandpass filter M PCA se ge ES ns 55 64 also see A law MACO iia Se eee Ee ee a Oe 351 Macro EILOF e ecu eos wa dow ws 353 Macro toolbar 22 23 Macro transiator 422 Makewave see Multitone Creation Utility Masking curve analysis 224 MATLAB 412 Maximum Compute algorithm 325 Maximum Regulation algorithm 357 Minimum Compute algorithm 325 Minimum Regulation algorithm 358 Modifying data with Compute 317 Monitor outputs 444446286 psss 339 Monitor Outputs
154. Audio Analyzer or the Digital Interface Analyzer is the Ana lyzer instrument and is grayed out under other conditions In a new test first select the Spectrum Analyzer as the Analyzer instru ment then click the Sweep Spectrum Waveform button This will auto matically enter Sweep panel settings for a two channel FFT spectrum ATS 2 User s Manual Acquired Waveform Files Chapter 11 The Spectrum Analyzer display Click Sweep Start and you will see the FFT plot on the Graph panel Click the Sweep Spectrum Waveform button again and the Sweep panel settings will be re set for a two channel waveform display Click again and the display will toggle back to a spectrum display Clicking the Sweep Spectrum Waveform button does not acquire or re acquire data it only re transforms the acquired waveform for time do main or frequency domain display Click Sweep Start to acquire new data Figure 146 ATS Sweep panel showing Source 1 FILFFT Freq E Waveform toggle button Start 20 0000 Hz Log Lin Stop 20 0000 kHz Hele Auto Steps 51 1 waveform Multiply fi 01361 Table Sweep Repeat e Stereo Sweep Append FP Single Point Once an FFT spectrum or waveform view has been set up on the Sweep panel a new button appears on the panel In waveform view this button is labeled Spectrum in spectrum view it is labeled Waveform This button controls the same toggling functions as the Sweep Spectrum Waveform button
155. Bal LA Figure 68 Analog Output Configuration Dut Ohms 600 Q impedance option Contiguration Bal sLA Do not unbalance the balanced outputs by connecting pin 2 or pin 3 of an XLR output connector to ground as might be done with adapter cables Connecting the ATS 2 balanced outputs to an unbalanced load will produce distorted waveforms Use the unbalanced output connectors for an unbalanced load See Chapter 4 for more information about the ATS 2 Analog Outputs Analog Generator References With the appropriate choice of units amplitude and frequency settings in the Analog Generator can be made relative to reference values These references are entered manually in the Analog Generator References ATS 2 User s Manual 95 Chapter 8 The Analog Generator Analog Generator References 96 area Freq and dBr references can also be entered on the fly from the cur rent generator settings as explained below Figure 69 Analog Generator References Heferenees Freq 1 00000 kHz dEr 387 3 rn watt 000 Ohms Bre J 00 0 Ohms dBr Amplitude Reference The dBr which is shorthand for decibels relative to a reference refer ence is an easy way to set a nominal level against which your settings or readings are made Enter a reference value in the References dBr field or load it on the fly from the current generator amplitude setting using the menu command Edit gt Set G
156. Bu 10 000 dBu 10 000 dBu 10 000 dBu 7 000 dBu 7 000 dBu 3 1 99990 kHz 7 000 dBu 7 000 dBu 2 00000 kHz 13 000 dBu 13 000 dBu 20 0000 kHz 13 000 dBu 13 000 dBu Figure 241 Creating a Limit Data in the Data Editor This will produce the limit traces shown in Figure 242 ATS 2 User s Manual 311 Chapter 18 Editing Data and Setting Limits Setting Limits 312 Figure 242 Limit Traces ARE shown on Graph S 20 5D 100 200 500 1K 2k AK 10k 20k Hz When you are satisfied with the limits you have created save the data as an AP limit file using the command File gt Save As gt Limit Data When making a limit file there are some constraints you must remem ber The Source 1 column of the limit data must correspond with the Source 1 parameter of the sweep the file will be attached to For example a frequency sweep test may have generator or FFT frequency as Source 1 and any limit files used with this test must also have frequency at Source 1 m There must be a Data column heading for each limit m The units of measurement for each limit data column must be in the same unit domain as the corresponding data in the sweep the file will be attached to You can save upper and lower limits in two separate files or you can save upper and lower limits as two different data columns in the same file If two measurements are to be compared against exactly the same limits as is often done in stereo sweeps
157. Chapter 7 ATS 2 User s Manual 247 Chapter 14 The Harmonic Distortion Analyzer The Fundamental Amplitude Meters 248 The Fundamental Amplitude Meters Figure 207 Harmonic Distortion Analyzer tha Analog Ch B Fundamental Amplitude Meters MEA E o y 1 00000 kHz Freg EN Two Fundamental Amplitude meters are located near the top of the Har monic Distortion Analyzer panel one for each input channel The Fundamental Amplitude meters display the rms value of the in put signal component at the frequency defined by the Steering control described on page 251 This is typically the stimulus signal frequency generated by ATS 2 s analog or digital generator This amplitude value is used as the reference for all ratio units dB ppm X Y when the Ratio box is checked for any Harmonic Sum meter The Fundamental Frequency Meters Immediately below the Fundamental Amplitude meters are the Fun damental Frequency meters or counters for the two channels These display the frequency of the dominant component of the input signal nor mally the fundamental signal This is the frequency that the Harmonic Distortion Analyzer s selective analysis capability will track when Coun ter Tuned is selected for the Steering mechanism The Frequency meters are only enabled when Counter Tuned is se lected Harmonic Distortion Product Amplitude Harmonic Sum 1 Figure 208 Harmonic Distortion Analyzer Product Amplitud
158. Eq 4 El Al el le El n A ei 10 0000 Hz 19 744 dBY 13 0000 Hz 19 631 dBY 16 0000 Hz 19 494 dBV 18 0000 Hz 19 389 dBY 20 0000 Hz 19 275 dBY 22 0000 Hz 19 152 dBV 24 5000 Hz 18 988 dBY 27 0000 Hz 18 813 dBY 30 0000 Hz 18 592 dBY a Nrsc pre atsq File name Riaa pre atsq Files of type Eq Curve File atsq 33 0000 Hz 18 360 dBY 36 0000 Hz 18 120 dBY 40 0000 Hz 17 790 dBY 45 0000 Hz 17 369 dBY 50 0000 Hz 16 943 dBV A Figure 56 EQ file attachment and editing Click the EQ Curve button to open the Equalization Curve dialog box then click the browser button to open the Equalization Curve file browser When you have selected an EQ file it will be attached to the generator panel and the file name will appear in the Equalization Curve dialog box The default amplitude data column is Column 2 you can choose another column from the drop down list in the Equalization Curve dialog box To view or edit the EQ file click the Edit button to open the Attached File Editor see page 313 You can create custom EQ curves by manually creating an ATS EQ file or by using the current sweep data in memory and a Compute function to produce an appropriate EQ file See Chapters 18 and 19 for more informa tion on saving data files and modifying EQ data from a sweep using Com pute functions Typical EQ Applications The most common applications of generator equalization are to produc
159. However the Q Peak choice is only effective on the Function meters If Q Peak is selected the Level meters use the normal rms detector Level Meter Units If you click on the arrow to the right of either Level meter reading field a list of measurement unit choices will drop down The units shown on the list depend upon whether Analog or Digital is selected in the Input field With Digital selected the units list includes m digital domain units FFS dBFS FS and Bits m relative units dBr A and dBr B m and units relative to the analog domain V dBu and dBV ATS 2 User s Manual The Level Meters Chapter 10 The Audio Analyzer These analog domain units are calculated relative to the value you enter in the V FS field in the References area of the panel and can be helpful in cross domain measurements When measuring an ADC for example you could enter the full scale analog input voltage of the converter into the V FS field and view your results here using one of the analog domain units available With Analog selected the units list includes m analog domain units V dBu dBV dBm and W watts m relative units dBr A dBr B dBg A dBg B m and units relative to the digital domain FFS dBFS and FS For an explanation of the units of measurement used in ATS and the ref erences for the relative units go to Appendix A Units of Measurement AC and DC Coupling There are a few issues to consider when examining AC and DC
160. Importing an APWIN test Appena Import at2c test file r The ATS 2 Test Translator appears as an additional menu selection in the ATS File menu Choose File gt Import gt at2c test file to open a file browser for translation See Figure 298 Navigate to the appropriate folder and select the test file you want to translate If you select only one file that test will be imported loaded into mem ory and saved as an ATS 2 test If you select multiple files all the selected files will be translated in a batch Each file will be first loaded into memory and then saved the last file opened will remain in memory Import Test 3 Diodnalpzer EX AE DIO CLOCK JITTER FFT at2c AS DIO INTERF EYE PATTEF AS DIO CLOCK JITTER WS TIME atc de pic INTERF FFT atec AS DIO D 4 JITTER TOLERANCE at2c Me pic INTERF JITTER WS T AS DIO D O JITTER TOLERANCE at2c debio INTERF PULSE IO AE DIO INTERF AMPL HISTOGRAM at2c Ae pic INTERF RATE HISTC AS DIO INTERF BALANCE atc debio INTERF WAWE amp JIT Apin files atc Figure 298 Selecting APWIN test s 420 ATS 2 User s Manual The Test Translator Appendix F Test and Macro Translators Test files will be saved with their original filenames but the filename ex tension will be changed to ats2 the ATS 2 test filename extension You should NOT import an at2c file into ATS in Demo Mode Instead have your ATS 2 hardware powered on and connected to your computer s
161. Introduction The AP Basic Extensions Reference for ATS 2 The AP Basic Extensions Reference for ATS 2 is a large supplementary li brary of OLE ActiveX automation commands for use specifically with ATS 2 The AP Basic Extensions Reference for ATS 2 is published in electronic form as a PDF file available on the Audio Precision Resources Disc and as a download from the Audio Precision Web site at ap com You will also find online Help for ATS 2 Basic Extension while running ATS Click Help gt AP Basic Extension for ATS 2 Help on the Help menu Application Notes and TECHNOTES From time to time Audio Precision publishes technical papers such as AP Application Notes and TECH NOTES which can help in your under standing of the operation of the ATS 2 system Many of Audio Precision technical publications are available for download from our Web site at ap com New technical papers and online solutions are added on a regular basis Viewing and Printing PDF files Audio Precision documentation is provided in Adobe Portable Doc ument Format PDF format on the Audio Precision Resources Disc and on our Web site at ap com You can view the PDF files using Adobe Acrobat Reader a free pro gram that can be downloaded from Adobe at www adobe com You can also print PDF files using Acrobat Reader and a Windows compatible printer GPIB Documentation for ATS 2 With Option GPIB hardware installed ATS 2 can also be controlled by the indust
162. Multitone Creation HS RIFF Waveform Creation Ea Utility MS RIFF Creation dialog box Waveform Length E Sec Bits Dither 14 re 15 Triangular Rectangular ore ATS 2 User s Manual Creating Multitone Waveform Files Chapter 13 The Multitone Audio Analyzer Final Options A final series of dialog boxes will open with some examples shown here ATS Basic Macro l ATS Basic Macro xj f e _ _ ATS Basic Macro _ You may reply Yes or No to any of these boxes At this point in the pro cess all the files you have requested have been created and saved so re plying No will not change or abort multitone creation The Yes options enable you to continue directly with your testing or to immediately view the statistics files ATS 2 User s Manual 243 Chapter 13 The Multitone Audio Analyzer Creating Multitone Waveform Files 244 ATS 2 User s Manual Chapter 14 The Harmonic Distortion Analyzer Figure 204 The Harmonic Distortion iaa E oOlx Analyzer panel strument Harmonic Distortion Analyzer 2468101214 135 711 dis B387 3 me watt s 000 Ohms dE mf oo o Ohms Introduction The Harmonic Distortion Analyzer is a DSP instrument selection on the Analyzer panel The Harmonic Distortion Analyzer permits flexi ble highly selective measurement of the amplitude of user specified har monic orders You can choose to measure any individual harmonic or the sum of any arbitrary sel
163. ON 4 4 40 24440856 ek aoe ae 46 ATS 2 User s Manual Go sweepcommand 266 GPIB ix cis eee we HERS EEX 7 31 Graph printing to a file 333 DUET 3 ee amp Be oe ee one E 294 comment 293 configuration 366 copy to clipboard 334 CUTSOPS ias nos esa as 289 export 1 ivocco nooo n d 334 legend 295 optionsmenu 287 overview 2 285 o lt lt ea ss e bea ee OES 329 sweep and table relationship 255 285 sweep display mode 265 titles and labels 293 ZOOM e cola us a ets ee ae BA Be 286 Graph bar see Bar graph Graphic aliasing 176 Graphing FFTs 400 Graphing Harmonic Dist Anlyzer results 254 Gray as reference trace color 294 H Hamming FFT window 164 Hann FFT window Digital Interface Analyzer 207 Spectrum Analyzer 163 Hardware status 368 Harmonic Distortion Analyzer bandwidth limitations 249 OvervieW 245 Harmonic selection in bandpass measurements 150 Harmonic sum meters Harmonic Dist Analyzer 2 4 248 Harmonic weighting filter see weighting filter Headphone monitoring 337 Headphone Speaker panel 338 Headphone Speaker source selection 338 Helomenu 22 18 He
164. ORD CONNECTOR This is a standard grounded connector for the mains power supply cord e FUSE HOLDER MAINS SUPPLY VOLTAGE JUMPER Open the cover of the fuse holder see the separate manual Getting Started with ATS 2 for access to the mains power fuse and the mains supply voltage configuration jumper card e MAINS SUPPLY VOLTAGE INDICATOR The white tip of the plastic indicator on the voltage configuration jumper card appears in one of four small holes to show the mains voltage selection m FUSE REPLACEMENT INFORMATION This chart lists the fuse values required for correct operation at the four supply voltage options a S N OPTION LABEL This label lists the Audio Precision serial number date of manufacture and hardware Performance Upgrade Option if installed m HEADPHONE JACK This is a 3 5 mm stereo jack suitable for driving headphones or other audio monitors m RESERVED FOR GPIB PANEL This blank panel can be removed for factory installation of the GPIB configuration option adding GPIB IEEE 488 2 General Purpose Interface Bus functionality to ATS 2 Operation under GPIB control is not covered in this manual ATS 2 User s Manual 33 m APIB INTERFACE This connector provides the two way Audio Precision Interface Bus connection between ATS 2 and the personal computer running the ATS control software m SYNC REF IN This connector provides an additional input for an external digital audio signal a squarewave or an N
165. Off M Track 4 The Analog Generator signal outputs are toggled ON and OFF by the OUTPUTS button Additionally each channel output can be switched indi vidually on and off by the CH A and CH B buttons on either side of the OUTPUTS button Both the main OUTPUTS button and an individual channel button must be switched on to route signal to the analog output circuitry Auto On If the Auto On checkbox is checked the Analog Generator is automati cally switched ON when a sweep starts and OFF when the sweep stops This is useful for power amplifier or loudspeaker testing With the genera tor set to OFF and Auto On enabled signal will only be applied to the DUT while the sweep is actually running ATS 2 User s Manual 79 Chapter 8 The Analog Generator The Analog Generator Panel S0 See Chapter 15 for more information on sweeps Also see Pre Sweep Delay on page 269 for a discussion of avoiding transients in the Auto On mode Amplitude Control and Units Figure 44 Setting the Analog Generator Amplitude al ells Ga eae N HE F Track A If the Track A checkbox is checked the amplitudes of both Channel A and Channel B are set by the Channel A Amplitude setting If the Track A checkbox is not checked the amplitudes of the two Ana log Generator channels can be controlled individually Type a value in the Amplitude setting field for either Channel A or Channel B and press En ter You can choose an amplitude unit of meas
166. Printing and Exporting Printing ATS Graphs Page Setup The Page Setup panel is available by the menu choice File gt Page Setup The page settings you make are saved when you save your work as an ATS test file along with the current data and the various instrument panel settings also included in a test file Page Setup Figure 259 Page Setup panel Display page a lt a lt 4 E soia Ea The Page Setup panel has three tabs On the Display page shown in Figure 259 you can select the page orientation the text and labels to be in cluded and how the graticule lines are to be printed Page Setup Figure 260 Page Setup panel Layout page Figure 260 shows the Layout page where you can set margins center the graph on the page or resize the graph to fill the page You can set margins either by entering numbers in the margin boxes or by dragging the page margins shown as dotted lines on the preview panel with the mouse pointer 330 ATS 2 User s Manual Printing ATS Graphs Chapter 20 Printing and Exporting To resize the graph drag the corner of the graph with the mouse pointer To move the graph on the page set the mouse pointer within the graph and drag the graph to a new location The Center and Fill Page checkboxes override any existing or manu ally set size and position adjustments On both the Display and Layout pages you have the option of saving your settings as new default settings You can also rese
167. Repeat operation Quasi AC Coupling Figure 136 ATS Spectrum Analyzer id Equiripple oc Coupled J coupling selections The Spectrum Analyzer can be dc coupled to the input signal or can op erate in one of two modes of quasi ac coupling The field at the right of the Window selection field offers three choices DC Coupled m Subtract Avg When Subtract Avg is selected the DSP computes the average value of all samples in the acquisition buffer and subtracts that computed value from the value of each sample before the FFT or waveform display is performed For noisy signals the Subtract Avg selection generally results in better dc rejection than the Subtract 1 2 pk pk selection a Subtract Y2 pk pk The Subtract 2 pk pk selection computes the maximum difference between positive and negative peak values in the acquisition buffer and subtracts half that amount from each sample before the FFT or waveform display is performed For symmetric low noise signals the ATS 2 User s Manual Averaging Chapter 11 The Spectrum Analyzer Subtract Y2 pk pk selection generally results in better dc rejection than the Subtract Avg selection The general effect of either of these selections is similar to having used ac coupling before acquiring the signal as long as no signal peaks ex ceeded digital full scale Use of either of the quasi ac coupling functions may be valuable when examining low level signals that have large dc offset
168. S functions The File Menu The File menu offers commands for opening saving appending import ing exporting and printing ATS files and access to the Quick Launch menu Since there are a number of different files types used by ATS submenus are available at the small black arrows accompanying some menu choices to choose for example whether to Save As a Test or Data or Macro file The listings at the bottom of the File menu show the last tests opened by ATS and provide a convenient way to quickly launch a previously used test Simply click on the name of the test you would like to open ATS 2 User s Manual 13 Chapter 2 The ATS Control Software The ATS Menus The Edit Menu The Edit Menu provides several groups of commands m Undo and Cut Copy and Paste provide editing functions for ATS text entries m Copy Panel to Clipboard places a bitmap image of the selected ATS panel on the Windows clipboard m The Set Analyzer and Set Generator commands provide an easy way to set reference levels and frequencies for the Analyzer and Generator panels for relative measurements These are discussed in detail in the appropriate chapters Reset Bar graph Max Min clears the gray minimum maximum excursion bar from a selected Bar Graph display m The four last commands are only active when the ATS Data Editor is open and selected and provide the means to insert add and delete data rows 14 ATS 2 User s Manual The
169. Sweeps and Sweep Settling Sweep Settling 278 The time interval starts when you click the Sweep Go button You can view the Time Sweep from the beginning if you have entered 0 000 s as your Start value The sweep will continue until your Stop value is reached As with generator sweeps you can enter the number of Steps or step Multiply in Log mode or Stepsize as Source 1 settings For very closely spaced readings ATS s ability to make measurements will be lim ited by other factors such as Sweep Settling or meter detector reading rates For example if your selected reading rate is 8 readings per second two consecutive readings cannot be closer than 125 ms At the very short reading intervals which are necessary to acquire mea surements which are close together the speed of your computer and the number of panels open in ATS and the windows open in other software running will have a noticeable effect on the speed of acquisition Sweep Settling Most of the measurements in ATS 2 are taken continuously often at rates as high as 32 or 64 readings per second The real time numeric meter displays show this raw data and you will notice that the readings jump around when the signal contains transients or other momentary disrup tions We mentally settle these measurements as we observe them ignor ing the brief extremes and taking the perceived average or trend as the reading If raw readings like this were plotted without
170. TPUT ANALOG INPUT CHANNEL A CHANNEL B CHANNEL A CHANNEL B sx amp 9 9 9 UNBAL Digital Output Digital Input Analog Outputs Analog Inputs Power Indicator Figure 8 ATS 2 Front Panel The analog inputs are configured on the software Analog Input panel the analog outputs are controlled from the Analog Generator panel A digital audio signal has two aspects the electrical interface signal and the information carried in the interface data stream Selection and electri cal configuration of the digital interface signal input and output is accom plished from the Digital Input Output DIO panel as are many characteristics of the data stream itself Additionally features of the audio embedded in the data stream are controlled from the Digital Generator panel See Specifications in Getting Started with ATS 2 for detailed hard ware specifications for both the analog and digital inputs and outputs ATS 2 User s Manual 35 Chapter 4 Signal Inputs and Outputs The Analog Outputs The Analog Outputs Ye Zo Don t float more than 0 5 V R typ 500 Q Electronically Floating Unbalanced Output Configuration Ve Zo Common Mode Test Output Configuration Figure 9 Analog Output Circuit Configurations simplified The ATS 2 analog outputs can provide a balanced output signal an un balanced signal or a common mode test signal The software output config uration selection affects both Channels A and B Th
171. TS Sweep function gives you the following capabilities m You can sweep a parameter as an independent variable across a range you define This can be an ATS instrument parameter set in Source 1 a table of pre defined values an external signal tracked as a sweep source or a time base to generate chart recorder type plots m As many as six other parameters called Data 1 through Data 6 can be measured during the sweep m You can choose from extensive lists of settings or readings for either Source or Data selections m You can set the number of sweep steps or the distance between the steps made within your range m You can impose pass fail limits on your results m You can specify the units and divisions displayed on your graph m You can set sweeps to automatically repeat m You can append successive sweeps on your graph m You can nest sweeps to generate curve families Data Editor 0 145 dBrA a 17 8250 kHz 0 065 dBrA 0 228 dBrA T 15 8875 kHz 0 013 dBrA 0 176 dBrA 3 14 1600 kHz 0 023 dBrA 0 140 dBrA 412 6200 kHz 0 051 dBrA 0 115 dBrA 511 2475 kHz 0 077 dBrA 0 089 dBrA 6 10 0225 kHz 0 106 dBrA 0 058 dBrA 7 8 93250 kHz 0 110 dBrA 0 055 dBrA 7 96250 kHz 0 122 dBrA 0 041 dBrA 7 Figure 213 Tabular display of sweep results graphed in Figure 212 256 ATS 2 User s Manual Plan Your Sweep Chapter 15 Sweeps and Sweep Settling Batch Mode Sweeps The ATS Sweep panel is also used to initia
172. TSC PAL video signal for sample rate synchronization house sync This connector also serves as the input for the Pass Thru generator function m MONITOR OUTPUTS These connectors provide audio signal monitor outputs The SOURCE monitor signals are routed from the input of the ATS 2 Analyzer at the Level meters the FUNCTION monitor signals are routed from the Analyzer Function meter monitoring the reading in process m TRIG IN This connector provides an input to trigger or initiate certain measurement functions m TRIG OUT This connector provides an output for the purpose of triggering an external oscilloscope m AUXILIARY CONTROL OUT A 9 pin DSUB connector to enable ATS 2 to control other instruments m AUXILIARY CONTROL IN A 9 pin DSUB connector for external control and display input m GROUND CONNECTOR This is a chassis ground connection suitable for bare wire or banana plug connection Power Recycle Time To assure stable operation after ATS 2 is switched off or loses power wait 15 seconds before re applying power ATS 2 User s Manual Chapter 4 Signal Inputs and Outputs This chapter discusses the hardware aspects of ATS 2 s main analog and digital signal inputs and outputs Monitor connections are discussed in Chapter 21 while sync reference and auxiliary connections are examined in Chapter 22 The primary signal input and output connectors are mounted on the ATS 2 front panel ANALOG OU
173. Tone bursts are often used as stimulus signals and can reveal character istics of a DUT s performance which are not observable with continuous tones The Analog Generator Sine Shaped Burst signal is essentially identi cal to the Digital Generator Sine Shaped Burst signal and both are sim ilar to the Digital Generator Sine Burst signal ATS 2 User s Manual Choosing an Analog Generator Waveform Chapter 8 The Analog Generator For both generators the Sine Shaped Burst has a raised cosine shaped envelope creating a relatively narrow energy spectrum around the sinewave frequency The Digital Generator Sine Burst has a rectangular envelope with fast rise and fall times and consequently a wider spectrum of energy Figure 53 Analog Generator Sine Shaped Burst panel wim Sine ShapedBurst Ch A F 1 0000 kH requency z rhe Burst i Cycles h Interval 3 Cycles h Low Level 10 0000 ka W Track A 1 000 E Amplitude 7 The frequency of the sinewave is set in the Frequency field The Ampli tude field sets the generator amplitude at the maximum burst ON level GENERATOR AMPLITUDE I I I LOW LEVEL i i l I I l le BURST ON I f lt INTERVAL _ gt Figure 54 Tone burst definitions using a shaped burst as an example Refer to Figure 54 for definitions of the following settings Burst Enter a value in the Burst On field to set the duration of the tone burst The
174. W Frequency References CHANNELA Digital CHANNEL A AC DC FREQUENCY Coupling METERS CHANNEL B CHANNELA CHANNEL A Detectors CHANNEL A Ranging RMS 1 005 V j LEVEL amp Fast RMS METERS CHANNEL B CHANNEL B Detector Amplitude Settings References CHANNELA CHANNELA CHANNEL A CHANNELA CHANNEL A Highpass Pee Detectors CHANNELA Eon aas Filters Weighting Ranging P Rvs Fast RMS gt EENI MEES AC Coupling mer amp Q Peak FUNCTION Highpass atest METERS iahti etectors lors Fiers Weighting Ranging Has Fast Rus gt EEIE AC Coupling amp Q Peak CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B Measurement Function AMPLITUDE Audio Analyzer Panel E Figure 109 Conceptual Block Diagram Audio Analyzer Amplitude Function The Amplitude function measurements are similar to the Level meter measurements In certain configurations the Amplitude function readings will be identical to the Level meter readings ATS 2 User s Manual 131 Chapter 10 The Audio Analyzer The Function Meters Amplitude measurements can differ from Level meter measurements for two reasons Amplitude measurements are affected by the highpass lowpass and weighting filter selections made in the BW and Fltr fields while Level meter readings are always unfiltered m In addition to the two rms detectors Amplitude function measurements may be made with the quasi peak detector the Level meters always use one of the rms dete
175. When Active Bits is selected the indicators display green for a bit that has changed state during the measurement period and black for a bit that has not Error Indicators Figure 34 The Error Flags DIO confidence lock coding panty invalid invalid Error Indicators ATS 2 User s Manual 67 Chapter 7 The Digital I O Panel The DIO Input Section 68 The ATS DIO panel contains four error indicators for characteristics of the serial digital signal The indicators are labeled Confidence Lock Coding and Parity Proper operation is indicated when none of the indi cators is lighted When an indicator lights it shows that some characteristic of the digital input signal is marginal or unacceptable Both the Digital Interface Analyzer and the Main Trigger panel can select a Parity Coding Lock or Confidence error flag to act as a trigger Two more indicators labeled Ch A invalid and Ch B invalid light when the Validity bit bit 28 the V bit of that subframe is asserted The Confidence Indicator The Confidence indicator lights when the ratio between the amplitude of the 3 Ul long pulse and the following 1 Ul long pulse in a subframe pre amble becomes large enough to cause an increasing probability of errors when slicing the input signal into logic high and low values This large ra tio occurs when the transmission bandwidth has been reduced to marginal or unacceptable values The Lock Indicator The Lock indicator lig
176. X 127 m Switcher panel The SWR 2755 series are auxiliary switching modules controlled by the ATS software See the user s manual provided with the SWR 2755 switchers m Bar Graphs panel See Chapter 17 m Data Editor panel See Chapter 18 m Digital I O Digital Input Output or DIO panel Ctrl I See Chapter 7 m Sync Ref Input panel See Chapter 22 m Status Bits panel Ctrl B See Chapter 7 m Headphone Speaker panel Ctrl H See Chapter 21 m Macro Editor panel See Chapter 23 m Regulation panel See Chapter 24 m Main Trigger panel See Chapter 22 m Auxiliary Control IO panel See Chapter 22 ATS 2 User s Manual 17 Chapter 2 The ATS Control Software The ATS Menus The Help Menu Tip of the day 475 Help ATS Basic Extensions Help AF Basic Language Help AF Basic Editor Help About ATS Release Hotes Audio Precision Web The Help menu gives you direct access to Online help and other infor mation m Tip of the Day opens the next Tip and allows you to enable or disable the Tips on software launch m AIS Help links to the Contents tab of the Main Help file for the control software Topics in this Main Help file can also be accessed as context sensitive help pushing F1 while the cursor is in a control or reading field m AP Basic Extensions help is the Help file that lists every AP Basic ActiveX Automation OLE command specific to the ATS 2 instrument Topics in this Help file can als
177. a 339 Overview ATS 2 Capabilities 3 system 2 222 2 22 2008 1 p 3 e saspe adenine eee oem 386 Pagesetup 02 330 Panels menu 16 Panels toolbar 22 Parity Dil amp emita amp GA we oe a 386 Pass thru feature 93 116 Pause sweep command 266 PCM 4 aaa arcadas 383 Peak equivalent sinewave 80 103 Peak picking 176 Peak values FFT display processing 175 Peaking filter see bandpass bandreject filter ATS 2 User s Manual Phase measurements Audio Analyzer 138 Phase unitS 380 Polarity digital interface signal 57 test waveform 93 115 Polarity inversion 102 Power entry module mains fuse and voltage selection 33 mains power cord 33 mains power switch 33 mains voltage indicator 33 Power recycletiMe 34 Preamble digital audio signal 385 Preemphasis also see deemphasis digital audio 56 Pre sweep delay 269 Printing graphS ba Hw ee Dea ew wo Es 329 pagesetup 330 Procedure see macro Procedure Editor see Macro Editor Procedure translator 422 Professional format digital interface 384 Pulse code modulation see PCM 0 Quasi peak detector see detector function meter
178. a new macro created in Learn Mode ATS 2 User s Manual AP Basic Documentation Chapter 23 Automating Tests The Macro Editor is a text editor with dedicated features for editing AP Basic macros including macro navigation and debugging tools You can begin a macro from scratch in the Macro Editor or edit macros created by Learn Mode or opened from disk AP Basic Documentation The AP Basic User s Guide and Language Reference is the primary refer ence for using automation with Audio Precision instruments Since each instrument has different capabilities each has a different set of OLE commands For ATS 2 these are discussed in detail in the AP Ba sic Extensions Reference for ATS 2 Both of these documents are included as PDF files on the Audio Preci sion Resources Disc ATS 2 User s Manual 355 Chapter 23 Automating Tests AP Basic Documentation 354 ATS 2 User s Manual Chapter 24 Regulation Regulation is a software servo mechanism which enables you to auto matically steer test parameters toward a specific measured value Let s say for example that you would like to find the point at which a power amplifier produces 1 THD N at its output With regulation ATS 2 can adjust a generator output amplitude while monitoring the DUT THD N guiding the generator up and down to the level where 1 THD N is measured At this point the DUT output wattage can be mea sured and noted as the power level at 1 THD N Figu
179. ach Channel B ATS 2 User s Manual TRIG OUT and the Main Trigger Panel TRIG OUT and the Main Trigger Panel Chapter 22 Sync Ref Trigger and Aux subframe each Y preamble in the interface signal received at the digital input If there is jitter in the received waveform that jitter will be reflected in the trigger waveform ChA Kcv Sub Frame DedJitt A trigger transition is generated at the beginning of each Channel A subframe each X preamble plus each Z preamble in the interface signal received at the digital input after the signal has been re clocked to remove jitter ChB Rcv Sub Frame DeJitt A trigger transition is generated at the beginning of each Channel B subframe each Y preamble in the interface signal received at the digital input after the signal has been re clocked to remove jitter Rev Block 192 frames A trigger transition is generated at the beginning of each Status Block frame each Z preamble in the interface signal received at the digital input This occurs once every 192 frames m Rev Error Four receive error conditions in the interface waveform are defined and flagged See Error Indicators on page 68 Select the error conditions which you wish to use as triggers in the check boxes on the Main Trigger panel When any of these selected conditions occurs in the interface signal received at the main digital input a trigger transition will be generated m ChA Xmit Subframe A trigger transition is
180. ackman Harris Maximum amplitude error is about 0 7 dB for a signal at bin edge Rife Vincent Windows Both Rife Vincent windows have smooth monotonically falling re sponses with no sidelobes The Rife Vincent 4 window has about 0 6 dB maximum amplitude error is about 100 dB at 7 bins off center and about 150 dB at 15 bins off The Rife Vincent 5 is slightly wider at the top of the main lobe with about 0 5 dB maximum amplitude error It has sharper skirts with attenuation reaching about 106 dB at 7 bins off center and about 150 dB at 12 bins off ATS 2 User s Manual Spectrum Analyzer Window Selection Chapter 11 The Spectrum Analyzer None No Window or Rectangular Window The None selection sometimes called a rectangular window does not apply any window function before the FFT This mode is normally used only with synchronous signals it is not generally useful for non synchro nous signals since energy will be spread across the entire spectrum unless the signal is exactly at bin center The maximum amplitude error due to the rectangular window attenuation is about 4 dB For synchronous sig nals there is no amplitude error None move to bin center This choice also does not apply a window function but it is not re stricted to signals that are synchronous None move to bin center may be used with any signal which consists only of a single sinewave and any harmonically related distortion products For signals
181. across the desired spectrum and then returns to a mid spectrum tone If End On is set to that mid spectrum tone it will note the first occurrence of that tone as the sweep passes through it and at the return the second occurrence of the tone will terminate the sweep Many pre recorded test tapes and CDs are made just this way with for example a 20 Hz to 20 kHz sweep followed by a 1 kHz reference tone When performing split site measurements with ATS 2 or another Audio Precision System the remote generator can be set up so that the generator dwells at its Generator panel setting which can be a mid band reference frequency before and after a Source 1 frequency sweep ATS 2 User s Manual External Sweeps Chapter 15 Sweeps and Sweep Settling Min Lvl The value set in the Min Lvl minimum level field allows you to ex clude any measurements below a preset level as measured by the meter specified in the field just to the right of Min Lvl This acts as a noise gate preventing noise or low level signals from interfering with the pro cess When Min Lvl is set very low all signals will exceed the setting and will be plotted when Min Lvl is set very high no signals will exceed the setting and nothing will be plotted This is useful in directing the sweep to ignore the silence between tracks on a test CD for example Start On Rules Additional external sweep controls called the Start On Rules have been added as OLE commands availab
182. actor See Creating Multitone Waveform Files on page 236 Channel A Phase When Fasttest ChA Phase is selected for Sweep Data in a Multitone test the readings are of the absolute phase of the acquired Channel A multitones relative to the corresponding tones at the ATS 2 generator The multitone signal must originate from a local ATS 2 generator and the Multitone Analyzer must be set to trigger from that generator The tones must not have had their phases randomized Channel B Phase When Fasttest ChB Phase is selected for Sweep data in a Multitone test you can select one of two phase measurements from the Ch B Phase field m Ch B This selection measures the absolute phase of the acquired Channel B multitones relative to the corresponding tones at the ATS 2 generator The multitone signal must originate from a local ATS 2 generator and the Multitone Analyzer must be set to trigger from that generator The tones must not have had their phases randomized m Ch B Ch A This B minus A selection measures the phase of the Channel B multitone signal tones relative to the corresponding tones in the Channel A signal For this to be meaningful the waveform for both Channel A and Channel B must be identical Use a mono multitone waveform filename extension agm Since a mono waveform has identical tones on each channel it is permissible to have used the Minimize Crest Factor feature in the creation of this file The phase rando
183. ain view is also available showing the multitone waveform as an oscilloscope style trace The time domain view does not change with measurement mode selection This view can be useful to observe the peak levels or crest factor of your multitone signal Click the Spectrum Waveform toggle button or choose Fasttest Time in the Sweep Source 1 browser to enable the time do main view See the table on page 233 for a listing of available and valid Multitone display modes and their results Frequency Resolution Figure 191 The Multitone Freq mome y 0 00000 Resolution field cis Z The Freq Resolution control has two functions m Setting Multitone triggering frequency resolution m Setting root sum square rss summing frequency resolution in Response and Distortion measurement modes Setting Multitone triggering resolution The Multitone Audio Analyzer has the ability to recognize a specific multitone waveform in the received signal by comparing the signal to the multitone file information passed from the ATS 2 generator When the fre quencies in the received signal match the generator frequencies the ana ATS 2 User s Manual FFT Length _ Chapter13 TheMultitone Audio Analyzer lyzer recognizes the incoming multitone and issues a trigger to begin the acquisition and analysis procedure If Frequency Resolution has been set to zero and the frequency of the in coming signal has been shifted Multitone will not recognize the wa
184. al of the detector reading rate value plus the time necessary for completion of the cycle of signal in progress when the reading rate period expires For example if the reading rate is set to 64 s a period of 15 6 ms and the signal being measured is a 500 Hz signal which has a 2 ms period the total time of each measurement could vary between 15 6 ms to almost 17 6 ms depending on the phase of the signal Quasi Peak provides a response conforming to the IEC468 specification for noise measurements and is normally used with the CCIR IEC468 weighting filter Detector Reading Rate Figure 118 The Audio Analyzer E BPYBR Fitr Freq Reading Rate selections Auto E Sweep Track dBrB f387 3 rei a wFs O00 Watte 3 000 Ohms dE mJe00 0 Ohme The left hand field following the Det label controls the detector read ing rate the rate at which all the Audio Analyzer meters update This is also called integration time The selections are Auto 4 s 8 s 16 s 32 s 64 s 128 s and 256 s The actual measurement time for a given selection depends on the de tector response type selected For RMS and Quasi Peak the measure ment time will be approximately the period of the selected rate for example about 125 ms at 8 s For the Fast RMS detector the rate se lected will set the minimum measurement period The actual period may 142 ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer be longer sinc
185. alue to approximately half the sample rate 24000 for a 48 kHz rate which results in a 0 5 second per step walking rate Slower computers may require a larger Samples Step value for proper display on the DIO panel Wfm Special Constant Value The Special Constant Value waveform provides essentially the same digital code at every sample This is the digital domain equivalent of an an alog DC signal Digital DC is usually dithered like most digital waveforms so the actual values at each sample will vary slightly by the amount of the applied dither There is no frequency control field for the Constant Value waveform The output Amplitude fields set the amplitude of the DC for each chan nel Wfm Special Random Special Random is a specific predictable pseudo random waveform uniformly distributed across the entire range of code values between plus and minus full scale It is intended for error rate testing of communications links AES3 interfaces and digital recorders Random is identical to the Bittest Random waveform of Audio Preci sion Systems One and Two and the RAND waveform of Portable One Dual Domain it may be used with the bit error analysis capability of any of those instruments Dither is disabled for the Random waveform Dither Dither is low level noise that is combined with the signal to improve lin earity reduce distortion at low amplitudes and extend the linear operating range below the theoretical minimum
186. alyzer Attached file considerations The filename extensions for attached files are different between APWIN and ATS The Translator detects these situations and makes copies of the attached files using the same filename and path but using the ATS file name extensions The attachment points in the ATS test will be changed to refer to the copied and renamed files Reporting Test Translation Exceptions The Test Translator will report the following conditions to the ATS log file m Tests containing Bar Graph and Sweep settings that had references to both Cascade Analog and Digital Analyzers and therefore could not be mapped to the single ATS 2 Analyzer m Settings that cannot be mapped because they are out of range for the ATS 2 Such settings are set to default values m Tests calling for a selection that is not available in ATS and no substitute is available that will result in proper operation The closest available substitution will be made but it is likely that you will need to make changes to the test In general features that do not exist in ATS 2 and therefore can never be mapped will not be reported since these conditions will occur in every test translation The Macro Translator Unlike the binary test files AP Basic macro files contain text that can be viewed and edited This makes it easier for you to check a translated macro and make changes if necessary ATS 2 User s Manual The Macro Translator Appendix F Tes
187. alyzer Instruments 0 43 Sweeps and GraphS ooa a a a a a a a a a a a a 44 Chapter 6 The Analog Input Panel 45 QUe oaa a a a a a a a a a a a a a a 45 Input Termination Option 46 Peak Monitors a a a a a a a a a a a a 46 Input Ranging aoaaa a a a a a eee a 47 Autoranging aaa aa a a a a a a a eee a a 47 Fixed Range aoaaa aa a a a a a a a a a a a a 47 DC Coupling aoaaa a a a a a a a a a 47 Converter and Sample Rate Selection 48 Chapter 7 The Digital I O Panel 51 The DIO Output Section 52 Format aaa a a a a a ee 53 Output Sample Rate OSR 54 Voltage aaa aa a a a a a a a a a 54 Output Resolution aoaaa aa a a a a a a a a a a 55 u Law and A law Compression 55 Preemphasis oaa aa a a a a a bee a a 56 Scale Freq DY ooo a a a a a eee a aa 57 Polarity oaa a a a a a a a a a 57 Send ErrorS oaa a a a a a a a a a aa 57 Changing the Parity bit 58 Sending a Validity bit 58 Jitter Generati0n aaa a a a a a a a a 58 Jitter Type aaa aaa a a a a a a a a 59 Amplitude oaoa a a a a a a a a a a a 59 Frequency 0 00 eee eee a a a 59 EQ CUFVe ooa a a a a a a a a a 60 The DIO Input Section 60 Format aaa a a e daa sa 61 Input Impedance aoaaa a a a a a a
188. alyzer instrument ATS 2 User s Manual Sync Ref Trigger and Aux In addition to the main analog and digital signal connections on the front panel ATS 2 provides a number of utility connections on the rear panel These include the the MONITOR OUTPUT connectors which are discussed in Chapter 21 and the APIB connector and GPIB connector if so configured which are discussed in Getting Started with ATS 2 In this chapter we will look at the remaining connections m SYNC REF IN m TRIG IN m TRIG OUT m AUXILIARY CONTROL OUTPUT m AUXILIARY CONTROL INPUT SYNC REF IN The SYNC REF IN BNC connection and the Sync Ref Input panel pro vide the ability to synchronize ATS 2 s master clock to several types of ex ternal reference signals including the sample rate or the frame rate of an AES3 or IEC60958 reference signal the horizontal sync frequency of NTSC PAL or SECAM analog video signals or to a squarewave or other periodic signal The master clock controls ATS 2 s internal sample rate and is the refer ence for all ATS 2 frequency measurements Synchronizing the master clock to an external reference is often necessary when making measure ments in an installation where house sync is used An AESS3 or IEC60958 digital audio signal applied to the SYNC REF IN connector can also be used as the Pass Thru signal available to the two ATS 2 User s Manual 341 Chapter 22 Sync Ref Trigger and Aux SYNC REF IN 342 signa
189. ample rate and textual information The AP downloadable filter format consists of one or more sample rates with accompanving filter coefficients in the form of second order sections ap write filter converts the filter into second order section form be fore writing it to the file This will require functions found in the MATLAB signal processing toolbox if the filter is not already in second order section form ap write filter accepts both filenames and file handles If a file name is supplied any extension is replaced with afl afh or afw depend ing on the filter type If the filename ends in the file is appended to or created if non existent ap write filter closes the file when the func tion exits If a file handle is supplied ap write filter appends to the file leaving it open on exit The arguments filter type info and sample_ rate are re quired filter type is the string 1 h or w for low pass high pass and weighting filters respectively a tor uses this informa tion to determine the filename extension and to restrict the number of sec ond order sections to the maximum allowed in the Audio Precision hardware for each filter type info is a character string that can be viewed inside ATS by clicking the Filter Info button after loading the filter This provides filter information to the ATS user sample rate a scalar is the sample rate in hertz for which the filter was designed See Multiple
190. ance pass fail limits to a test See Setting Limits page 310 Data 2 Data 2 enables you to plot a second trace of data on your graph against its own scale and calibration on the right hand graph axis Data 2 operates in exactly the same way as Data 1 with these excep tions m Data 2 plots against the scale on the graph right Y axis or if the X Y Data2 on X option button is selected m Data 2 determines the X axis calibration to enable you to plot two measured values or readings as an X versusY graph See below for an explanation of plotting data X Y When Data 1 and Data 2 are plotted together on a graph the Data 1 Top and Bottom range settings and intermediate values are displayed on the graph left Y axis The Data 2 Top and Bottom range settings and in termediate values are displayed on the graph right Y axis Plotting Data as X versus Y Sometimes it is useful to plot two measured values against one another under stimulus from a third signal ATS 2 User s Manual 263 Chapter 15 Sweeps and Sweep Settling Data 3 through Data 6 264 In a Data X versus Y graph Data 1 is still plotted on the left Y axis Source 1 is still the independent variable stepping through the Start Stop range and driving the test to create the changes in the Data 1 and Data 2 dependent variables which will be plotted However Source 1 values and calibration will not be displayed on the graph at all instead Data 2 values are used to
191. and define your primary data result the depend ent variable which changes in response to Source 1 In graphing a sweep Data 1 is shown as a trace or curve whose values are always read on the graph left Y axis A discussion of Data 2 begins on page 263 and Data 3 through Data 6 are discussed on page 264 Selecting the Data 1 Reading The default reading for Data 1 is the Analyzer Level A amplitude To select a different reading click on the Data 1 browser button ATS 2 User s Manual 261 Chapter 15 Sweeps and Sweep Settling Data 1 262 Browser Sweep Data 1 3 Instrument Parameter Level A Amplitude A Amplitude 6 Frequency E Frequency El e Show Readings Show Settings Figure 216 The Sweep Data 1 browser dialog box A dialog box will open which displays the instruments and parameters available as data readings Click on a instrument and you will see the read ings associated with it in the right browser window Top and Bottom Values Enter the graph top and bottom values in the Top and Bottom fields in the Data 1 section of the Sweep panel Drop the arrow list to change units of measurement Since Data 1 displays the results of measurements it is not always possi ble to predict the range of the values If you set the Top or Bottom values too low or high the data will still be acquired and saved but the graph trace will not extend beyond the set values In this case you can re enter the Top or Bo
192. anel Professional Format Status Bits Figure 38 Transmitting Professional A Status Bits Digital 170 Format Status Bits EA CO Consumer Normal C Non ndio Emphasis Not Indicated Freg Mode Locked Sample Freg Mot Indicated Channel Mode Not Indicated User Bits None Ausiliarn Bits 20 bit undefin Audio Wordler Mot indicated Ref Signal Not a ref sigr Origin Desk Hl Local Address 0 Time of day 0 Reliability Flags 0 5 14 17 set unreliable 6 13 f 18 21 CRC Enable With the option buttons and drop down lists shown here you can set any of the professional format status bit conditions See page 386 for more information about Channel Status and for detailed tables of the profes sional format status bit fields and interpretations Local Address and Time of Day entry If the Auto Incr box is checked ATS automatically enters a continu ously increasing count in audio samples in both the Local Address and the Time of Day fields The count begins at the moment the professional format is selected or at the moment the Auto Incr box is checked which ever occurs later If the Auto Incr box is not checked you may enter a fixed number into either field ATS 2 User s Manual 73 Chapter 7 The Digital I O Panel The Status Bits panel 74 CRC entry The AES3 professional standard defines status byte 23 as a cyclic redun dancy code CRC byte to assist the receiver in detecti
193. ap these but it ATS 2 User s Manual 429 Appendix F Test and Macro Translators Mapping exceptions and substitutions is more than likely incorrect and will need to be modified by the user to obtain the desired behavior if necessary The Harmonic analysis program in System One is very different from the Harmonic Analyzer used in System Two Cascade and ATS 2 The translator attempts to map the S1 Harmonic program to the ATS 2 Audio Analyzer as it is more similar to the System One program but this will likely need to be reworked by the user Digital 1 0 Cascade Serial and Parallel I O modes are not supported and are mapped to XLR in ATS 2 Cascade Dual BNC I O modes are not supported and are mapped to Dual XLR modes in ATS 2 Random and Squarewave jitter generation modes are not supported These are mapped to sinusoidal jitter Equalization on digital output streams is not supported These settings are mapped to equivalent non equalized settings Embedded audio in the digital output cannot be scaled by the Measured Output Rate This setting is mapped to Output Rate The XLR Common Mode digital input configuration is not available in ATS 2 This setting is mapped to XLR Compute Functions 430 Compute Sigma is not available If a test is imported with Compute Sigma in the Compute Status list this list entry will be deleted ATS 2 User s Manual A AATE a aia oe oe Bw Bee st 212 AMO os ey ee ee e
194. apter 15 Sweeps and Sweep Settling The Start Stop and scale controls Log Lin Div and Auto are still available but they no longer affect the performance of the sweep they are only used to set the graph calibration and divisions If you set the graph range in Start and Stop narrower than the range of the values in the sweep table there will be points beyond the range which will not be plot ted If instead of attaching an existing sweep table you would like to create your own open the Data Editor panel by clicking the Data Editor button or using the Menu command Panel gt Data Editor You can enter edit and delete values in the Data Editor to create your sweep table Save the contents of the Data Editor as a sweep data file atss using the Menu com mand File gt Save As gt Sweep Tables External Sweeps All the sweeps we ve discussed are internal sweeps that is the parame ters and settings for the Source 1 independent variable come from within the ATS 2 system whether they are generator settings or data from a sweep table It is also possible to use an external signal as the independent variable For example a CD alignment disc may have a frequency sweep as a test track and to test the playback capabilities of the CD player you may want to perform a response sweep with the disc as the signal source This is called an external sweep The Sweep panel settings for an internal sweep not only set and sweep the generator pa
195. ara Ieee sue TUai o apresar ol Description ap read filter imports an Audio Precision downloadable filter text file into MATLAB It parses the file and returns a structure array of filters one structure for each sample rate contained in the file It also returns the info comment strings The file is closed on exit The AP downloadable filter format consists of one or more sample rates with accompanving filter coefficients in the form of second order sections ap read filter creates one structure in the output array for each sam ple rate in the file Each structure contains the sample rate and a matrix consisting of the filter in second order section form If other forms are re quired such as state space the signal processing toolbox conversion func tions should be used Comments in the file are discarded but info strings are concatenated into the returned info variable The info strings are used by ATS to pro vide information to the user when the Filter Info button is clicked ap read filter attempts to deal with syntax errors in the file by issu ing a warning of the line number of the error ATS 2 User s Manual MATLAB Downloadable Filter Support Appendix D User Downloadable Filters Example To read the filter file generated by the first example in ap read fil Cer This returns a 1 x 3 structure array Typing filters 1 at the prompt returns ano omple ee 3 A010I0 sos 2x6 double The second order
196. ata 1 Horizontal alue Data 2 fi 0000 kHz Data 3 Data 4 Data 5 Data 6 Compute Cancel Close Compute And close To invert a trace first decide what the pivot point of your inversion should be that is which data point you would like to remain constant when the trace is flipped Enter the X axis value of that data point in the Horizontal Value field The trace inversion will be performed around this point when the data is computed Compute Smooth Compute Smooth smooths out a trace by assigning each data point a new value which is the value of the average of that point and the two points on either side of it 320 ATS 2 User s Manual Compute Linearity Chapter 19 Performing Computations on Data Figure 250 Compute Smooth Dialog Box Data to Compute p Apply After Sweep Data E Passes Data 2 fi Auto Data 3 a Data 4 Data 5 Data 6 Compute Cancel Clase Compute Any close The data can be passed through this process repeatedly with each pass increasing the smoothing The default number of passes is 1 you can spec ify a greater number of passes by entering a higher number in the Passes field If the Auto box is checked the Passes field will not be available for entry and ATS will automatically select a number of passes based on the number of measurement points in the data specifically if Auto is checked the number of passes is the integer nearest 1 2 x num
197. ata in memory select SweepData To use a data file click the browser button and navigate to the file In either case once you have selected a Delta Source you must then choose a data trace in current memory and the Delta Source data col umn you wish to subtract from it Compute Average Compute Average calculates the average value for all the data points within the range you specify in the Start Value and Stop Value fields All the values for the entire data set will be replaced with this computed av erage including data points which may be outside the range you set for calculating the average Figure 254 Compute Average Dialog Box X 1 20 0000 Hz 0 0000 kHz 324 ATS 2 User s Manual Compute Minimum Chapter 19 Performing Computations on Data Compute Minimum Compute Minimum will find the minimum value in a data set exam ining all the data points within the range you specify in the Start Value and Stop Value fields All the values for the entire data set will be re placed with this minimum value including data points which may be out side the range you set for examining the data Figure 255 Compute Minimum Dialog Box 0 0000 Hz 0 0000 kHz Compute Maximum Compute Maximum will find the maximum value in a data set exam ining all the data points within the range you specify in the Start Value and Stop Value fields All the values for the entire data set will be re placed wi
198. ater than 1 000 FFS ora combination of values in EQ Sine or Sine Offset modes for example which would result in a value greater than 1 000 FFS an error message is displayed Waveforms other than a sinewave are calibrated in peak equivalent sinewave terms that is the Amplitude setting field is calibrated to show the rms value of a sinewave with same peak value as the waveform se lected Selecting a squarewave with an Amplitude value of 100 0 Vrms on the Digital Generator panel for example produces a 141 4 mVp squarewave signal Choosing a Digital Generator Waveform The Digital Generator offers a wide choice of test waveforms selectable from the primary and secondary waveform lists Figure 74 Digital Generator Primary Digital Generator Waveform Selections T Auto O W Track A T Invert 0 eres a Invert fi OOO FFS Amplitude These list selections are for the most part sorted by the shape of the waveform such as sinewave squarewave noise and so on Most wave form choices have an associated secondary list from which you make your final waveform selection This chapter organizes the waveforms by shape The variations avail able on the secondary lists are described under each section Sine waveforms This section describes the sine waveforms available to the Digital Gener ator which cover the frequency range from 2 Hz to just under 50 of the ATS 2 User s Manual 103 Chapter 9 The Digital Gen
199. ation on page 355 Editing the Current Data in Memory In the Data Editor window you can enter or change data in any cell by selecting the cell with the mouse pointer and entering or deleting the value For other editing options right click within the Data Editor window The Data Editor menu will open and provide the following choices m New Data New Data erases all the information in memory and cannot be undone m Insert Row Before inserts a row before the currently selected row m Insert Row After inserts a row after the currently selected row ATS 2 User s Manual 309 Chapter 18 Editing Data and Setting Limits Setting Limits 310 Add Row to the End will add one row to an empty data table or will add one row below the last existing row m Delete Row deletes the currently selected rows Select all rows Unselect all rows Saving ATS Data The information in the Data Editor is saved on disk along with other in formation as part of an ats2 ATS test file When a test is loaded the test information becomes the current data and is viewable in the Data Editor The current data shown in the Data Editor can also be saved in several types of data only files which ATS uses for different purposes as follows m Data atsa file Data files can be reloaded as current data m Limit atsl file Limit files can be attached to a sweep to provide upper and lower pass fail limits against which to compare the current
200. ator m Fixed Fixed sets the fundamental frequency to the value you enter in the field to the right High Speed High Accuracy Control Hi Speed Counter Tun Hi Speed le d r B 387 3 mi The Harmonic Distortion Analyzer is normally configured to pro vide accurate results quickly Figure 211 Harmonic Distortion Analyzer Distortion High Speed High Accuracy selection y When making measurements of distortion products which are lower than 90 dB or 100 dB lower than 0 003 to 0 001 relative to the fundamental you can choose to set the instrument to a mode of even higher accuracy at the price of some sweep speed In the field to the left of the Steering control choose High Accuracy to enable this mode The default mode is High Speed 252 ATS 2 User s Manual Harmonic Distortion Product Amplitude Chapter 14 The Harmonic Distortion Analyzer THD vs THD N Measurements of THD N total harmonic distortion plus noise us THD total harmonic distortion not including the effects of noise on the same signal may differ for two reasons one theoretical and the other due to the architecture of typical THD N analyzers The theoretical difference between THD and THD N lies in the N term the noise If distortion products are much higher in ampli tude than the wide band noise in a signal the two techniques should give essentially identical results In many cases with modern well de signe
201. atted text file con taining information defining the characteristics of the filter The filter must be named with one of these extensions m for a low pass filter afl m for a high pass filter afh m for a weighting filter afw As long as the file meets the specifications set out below you can create the filter by any means including the use of a text editor or third party soft ware that has digital filter design capabilities User Downloadable Filter Design Constraints m Each file specifies a single infinite impulse response IIR filter at one or more sample rates Each IIR filter can be implemented by cascading one or more second or der sections shown here 1 2 _ Dy Dye Fz l a z a z H z First order sections are not allowed a first order section can be imple mented with the second order section by setting b and a to zero m A low pass filter may not have more than 6 poles or 6 zeros that is a low pass filter can have at most three second order sections m A high pass filter may not have more than 4 poles or 4 zeros that is a high pass filter can have at most two second order sections ATS 2 User s Manual 401 Appendix D User Downloadable Filters Creating User Downloadable Filters m A weighting filter may not have more than 8 poles or 8 zeros that is a weighting filter can have at most four second order sections Unstable filters are not allowed An unstable filter is a filter with p
202. azardous condi tion such as the presence of dangerous voltage that could pose a risk of electrical shock Refer to the accompanying Warning Label or Tag and ex ercise extreme caution ATTENTION This symbol alerts you to important operating consider ations or a potential operating condition that could damage equipment If you see this marked on equipment consult the User s Manual or Opera tor s Manual for precautionary instructions FUNCTIONAL EARTH TERMINAL This symbol marks a terminal that is electrically connected to a reference point of a measuring circuit or out put and is intended to be earthed for any functional purpose other than safety PROTECTIVE EARTH TERMINAL This symbol marks a terminal that is bonded to conductive parts of the instrument Confirm that this terminal is connected to an external protective earthing system ATS 2 User s Manual Introduction Figure 1 The Audio Precision ATS 2 audio test and measurement system ATS 2 an Overview The Audio Precision ATS 2 is a powerful computer controlled audio test and measurement system The ATS 2 system consists of two key compo nents m The ATS 2 hardware which provides the connectors and circuitry necessary for proper signal interface and precise signal generation and analysis The hardware is mounted in a compact aluminum and ATS 2 User s Manual Chapter 1 Introduction About This Manual steel chassis which can be installed in a standard 1
203. be mapped correctly APWIN allowed each channel to select among a variety of input sources that included points within the Analog Analyzer signal path and also the recovered jitter signal In ATS 2 the input sources are always the front panel inputs All APWIN Digital Analyzer sources are mapped to these ATS 2 inputs Test Trans If remapping of incompatible source selections occurs a message will be written to the log file Macro Trans If remapping of incompatible source selections occurs the incompatible source selections are commented out Most ot the APWIN FFT Analyzer sources are not supported in ATS Digital and analog inputs are mapped correctly as is the recovered jitter signal for analysis channel B Other sources will be mapped to Analog inputs If incompatible source selections were in the APWIN test a message will be written to the log file m Depending on the options installed certain input terminations may not be supported for ATS 2 inputs In APWIN three balanced input terminations are available 300 Q 600 Q and gt 100 kQ Ina standard ATS 2 only gt 100 kQ is available The 600Z option adds an additonal input termination choice of 600 Q Test Trans If the ATS 2 does not have the 600Z option installed all input termination choices will be mapped to gt 100 kQ If 600Z is installed gt 100 kQ will be mapped to gt 100 kQ and 300 Q and 600 Q will be mapped to 600 Q A message will be generated in the log file if the
204. be saved as a separate file ATS can open saved data files in order to attach previous data to a cur rent test There are four different data file types each of which has a differ ent use within ATS The extensions for data files are m AP data file atsa m AP limit file atsl m AP sweep file atss m AP EQ file atsq The four ATS data file types are identical except for their file name extensions Data saved as atsa atsl atss or atsq files can later be used for any data function The different extensions serve to help organize data files and to indicate the intended use of the data It is also possible to export ATS data as an ASCII text file for use in a spreadsheet or text editor program The extension for an ASCII data file is m AP ASCII data file atsx Waveform Files For certain analyzer functions performed in DSP including FFT displays and some types of interface analysis ATS acquires a short sample of the digital waveform These samples can be saved as waveform files and later opened by ATS for further use The extensions for waveform files are m AP stereo waveform file generator ags m AP stereo waveform file analyzer aas m AP mono waveform file generator agm m AP mono waveform file analyzer aam a AP digital interface waveform file aai ATS 2 User s Manual Keyboard Shortcuts Chapter 2 The ATS Control Software Dozens of sample tests and associated files for the ATS 2 ar
205. ber of points but is never fewer than 3 Smoothing is useful when you suspect some of the more extreme data points are spurious Loudspeaker measurements for example often show large peaks and dips which are often attributed to room reflections rather than speaker response Smoothing out such a trace may provide a more useful view of the speaker response Compute Linearity Compute Linearity graphically displays the variance of each of the measurement data points from a linear response across all the data In the first of two mathematical operations the best straight line is fitted to the data across a range you can specify This line is computed using the least squares method Next the value of every data point is subtracted from this straight line the result is a graph of deviation from perfect linearity This is useful to eval uate input output amplitude linearity of an ADC or DAC or of the in put output phase shift of a loudspeaker for example ATS 2 User s Manual 321 Chapter 19 Performing Computations on Data Compute Center Figure 251 Compute Linearity Dialog Box MATH patato Compute Ai er Sweep Bo Start Value J Data 2 20 0000 Hz Datas Stop alue Data 4 20 0000 kHz Data s Data 6 Compute Cancel Close Compute And close Typically a DUT will have its greatest nonlinearity at the measurement extremes To keep this atypical data from affecting the initial straight line fit ting you
206. box to defeat autoranging The range set ting field for that meter and channel will become active and you can enter a fixed maximum range for that input Fixed Range Using a fixed range produces faster measurements which can be impor tant when speed is at a premium as within a repetitive routine in an auto mated testing macro However you must know the probable range of the signal and set a maximum above the highest expected level Manual range selection is also preferred when using signals which vary quickly such as tone bursts or program material such as voice or music Automatic ranging will constantly switch levels when a complex wide range signal is applied This may make it difficult to adjust a device for minimum distortion or noise for example DC Coupling ATS 2 s analyzer circuitry can be DC coupled from the front panel con nectors to the input of the ADC circuits With DC coupling enabled DSP acquisition of analog signals is extended down to DC ATS 2 User s Manual 47 Chapter 6 The Analog Input Panel Converter and Sample Rate Selection Converter amp Sample Aate HiRest655365 h HiResmb5536 a HiResB05A HiB 31072 HBg A HIB 2201S 48 DC coupling also provides a superior common mode rejection ratio CMRR at low frequencies which is normally limited by the inevitable small mismatch in the values of the coupling capacitors that serve to block the DC You can choose to pass the DC compone
207. brated analog output signal that is the signal will have peaks equal to those of a sinewave of the rms value set in the Analog Generator amplitude field Configuring the Analog Outputs The analog output configuration is controlled from the Analog Genera tor panel Both A and B outputs are configured together The choices are Bal XLR a balanced signal on the XLR male connectors pin 2 high UnBal BNC XLR an unbalanced signal available on both the BNC and the XLR male connectors pin 2 high a CMTST XLR a common mode test signal on the XLR male connectors both pins 2 and 3 high 94 ATS 2 User s Manual Analog Generator References Chapter 8 The Analog Generator Figure 66 Analog Output Configuration Out Ohms Configuration Balanced Bal LA C 40 te 150 Bal LE UnBal ENCALA 7 CMTST XLF You can also choose one of two output impedances using the option but tons These impedances are available for the balanced and common mode configurations m if your ATS 2 was ordered with the standard output impedances the choices are 40 Q and 150 Q m if your ATS 2 was ordered with the Euro impedance option the choices are 40 Q and 200 Q m if your ATS 2 was ordered with the 600 Q impedance option the choices are 40 Q and 600 Q The impedances available for the unbalanced configuration are always 20 Q and 50 Q Figure 67 Analog Output European impedance option Dut Ohm Configuration
208. by low frequency noise so the value of jitter measured is likely to be a strong function of the bandwidth of the measure ment Four bandwidth selections may be selected for jitter measurements m 50 Hz 100 kHz m 120 Hz 100 kHz m 700 Hz 100 kHz and ATS 2 User s Manual 69 Chapter 7 The Digital I O Panel The Status Bits panel 70 a 1200 Hz 100 kHz Jitter may be plotted on a graph as a function of some swept parameter such as time or transmitted jitter amplitude choose Dio as the Sweep Data instrument and Interface Jitter as the parameter Using the Spectrum Analyzer instrument you can select the Jitter sig nal and display either the jitter waveform or an FFT spectrum analysis of the jitter signal See Spectrum Analyzer Signal Inputs on pace 156 Jitter may also be measured according to an entirely different technique by the Digital Interface Analyzer instrument described in Chapter 12 The Status Bits panel Channel status bits are administrative or housekeeping data carried in the AES3 and IEC60958 serial digital interfaces Each subframe has one C Channel Status bit bit number 30 The bits are gathered and ar ranged into channel status blocks of 192 bits marked off by the block start code which occurs in the interface preamble at intervals of 192 subframes Bit O in the status block identifies the format as professional or con sumer The information in the status blocks differs for the most part be twe
209. cale Freg by REN 015p Ode Polarity BO 15ps 12dB 417 20dB The embedded audio of the digital output signal may be transmitted without preemphasis as is normal or preemphasized according to one of two different functions Preemphasis is rarely used The consumer format has only one defined preemphasis condition the 50 15 us Compact Disc preemphasis The professional format adds the CCITT J17 preemphasis Either preemphasis function may be selected at normal gain or with a headroom allowance of 12 dB 50 15 us or 20 dB J17 if there is a concern that high level test signals would exceed clipping digital full scale after preemphasis has been applied Matching deemphasis and gain selections are available in the Deemphasis field of the Input section of the DIO panel to provide over all unity gain and flat response 56 ATS 2 User s Manual The DIO Output Section Chapter 7 The Digital I O Panel Scale Freq by Figure 20 The DIO Scale Freq by selections Scale Freq by Output Rate Polarity Output Rate DIO Rate Ref Trent For a digital audio signal of a given sample rate the embedded audio will be shifted in frequency when the same data is transmitted at a different sample rate The audio frequency will change by the ratio of the two sam ple rates For example a 1 kHz audio signal generated in DSP at a 48 kHz sample rate would be converted to a 666 67 Hz signal if transmitted at a 32 kHz samp
210. calibrate the X axis As an example you can perform an amplitude sweep Source 1 ona power amplifier and plot the measured percent distortion Data 1 on the Y axis against the measured power output Data 2 on the X axis The amplitude sweep itself is never displayed as such however the two sets of results are graphed to show their dynamic relationship You can switch between the conventional X Y mode and the X Y Data2 on X mode at any time using the option buttons on the ex panded Sweep panel Limits cannot be graphed and data cannot be compared to limits when the graph is in X Y Data2 on X mode Data 5 through Data 6 If you are viewing the Sweep panel in its compact mode and one or more of the Data 3 through Data 6 functions are in use these will be listed in the Sweep panel title bar between sets of arrows as shown below if Sweep gt gt Data 34 gt gt Joj xj Cata 1 Analyzer Level A E Top 16 00 Y Autoscale Bottom 1 000 rity Y f Logt Lin Divs I Auto Limits Figure 217 Compact View of the Sweep Panel with Data 3 and Data 4 active Data 3 through Data 6 enable you to plot up to six variables when used with Data 1 and Data 2 These additional Data functions operate in exactly the same way as Data 1 and Data 2 with this exception to be plotted on the graph they must share a graph calibration scale the hori zontal scaling lines and the corresponding numerical legend displayed on the
211. cesses and of course open and operate the instru ment panels where the core test and measurement work is performed ATS 2 User s Manual Chapter 2 The ATS Control Software The Workspace 10 The Workspace IZA Audio Precision ATS Untitled File Edit View Panels Sweep Compute Macro Utilities Window Help Frequeney 1 00000 kHz IE T Auto Onfena Outputs fene Y Track A 1 000 ims f Amplitude Measurement Function mn y y Configuration Z Dut Ohms DetfAuto Er faxa z 540 cew Ev ERM ESca A A Fitr None y 7 References References Freg 1 00000 kHz dBr 387 3 mi x dBrA 387 3 mv dBrBj387 3 my y watts 8 000 Ohms dBm 500 0 Ohms Freq 1 00000kH2 W FS 1 000 Y Watts 8 000 Ohms dBmj600 0 Ohms For Help press F1 Figure 3 The ATS workspace The ATS workspace has 5 pages that you can select by menu com mands View gt Page or by clicking the numbered tabs on the Status Bar The workspace is like a multi layered desktop where you can display and organize the instrument panels you are using for a particular set of tests Panels can be placed on any workspace page and duplicated on more than one page An instrument panel which appears on more than one page is simply a redundant display for your convenience The settings and results shown on redundant panels are identical and a change made on one page is reflected on the others The ATS Panels The real interaction with ATS 2 is done
212. ch will be varied in an attempt to steer the target parameter toward the desired value Use the source browser to 356 ATS 2 User s Manual Chapter 24 Regulation select the source parameter from the ATS instrument settings provided m source High and Low Bounds These are the extremes between which you want to confine the source variations There are also several panel settings which affect regulation perfor mance m Operation Operation sets one of five algorithms which determine how the regulation operation proceeds Linear The assumption for Linear operation is that any change in the Regulation Source parameter will cause the same change in the regulated Target parameter This is the normal relationship for example in the input and output amplitudes of an amplifier a 2 dB change at the input should make a 2 dB change at the output Linear is the best choice and the fastest option for setting DUT outputs to a reference level or making frequency response measurements at a constant output level In Linear operation the regulation algorithm is directed to jump to the Target value in a sinale step and the Stepsize field is unavailable Normal The assumption for Normal is that any change in the Regulation Source parameter will cause a proportional change in the regulated Target parameter This is the normal relationship between generator amplitude and measured THD of an amplifier near its maximum power point or betwe
213. ck EZ zj Marrow Freg 3 g arrow Freg 4 Narrow Freg 5 Jo ODO Lr dEm b00 0 Ohms The default setting Narrow sets the filter at the source frequency The other choices Narrow Freq x2 Narrow Freq x3 and so on move the filter to multiples of the source frequency allowing you to make individual harmonic distortion measurements of the 2nd through 5th harmonic The filter bandwidth is fixed at the normal 5 2 bandwidth value under all of these selections but its center frequency is steered to different integer multiples of the BP BR Source steering frequency See BP BR Filter Tuning on page 149 References The bottom area of the Audio Analyzer panel includes six fields with Input Analog or four fields Input Digital in which you can enter ref erence values Each reference serves as a basis for its corresponding unit of measurement on the panel The Freq and V FS references are the same for both the Analog and Digital inputs the other reference fields will change with the input configuration Analyzer Analog References Figure 125 Analyzer References Analog References dBr A 387 3 mi dBr B 387 3 mi Freq 0000 kHz WiFS I 00 Y tufatts 8 000 Ohms dBm e00 0 Ohms m dBr A and dBr B When the Analyzer Input is set to Analog the dBr A and dBr B values serve as the analog references for the dBr A and dBr B units selectable at any meter measuring amplitude m Freq The frequency Freq value
214. coding This scheme provides a transition at the beginning of every data bit and a second tran sition in the center of the bit if the bit is a data 1 Bi phase mark encod ing ensures that there is at least one transition for each data bit no matter the state of the bit or the state of neighboring bits The bi phase mark pattern is broken for the three types of preambles as a means of identifying the frame subframe and block beginnings The Frame and Subframe Figure 288 shows the AES3 data pattern The frame is the basic subunit and is comprised of two subframes called subframe A and subframe B The frame rate is normally the same as the sample rate a signal sampled at 44 1 kHz will normally be carried on an interface signal running at 44 100 frames per second Each subframe carries one word of audio Normally subframe A will carry a word of audio A nominally the left channel subframe B usually carries audio B the right channel Other assignments may be made though and in dual connector operation both subframes A and B may be subsequent words of the same audio channel with the second channel car ried on the second connector In multitrack applications subframes A and B may carry audio channels 7 and 8 for example Each subframe has the following structure 0 34 2728 31 LSB 24 bit Audio sample word MSB V UICIP Figure 289 The AES3 frame First there is a preamble which has a lenath of 4 data bits The pream bles
215. ctors Since the Level meters have no equalization or filtering available you must use the Amplitude function for weighted or band limited noise mea surements 2 Channel Ratio Function CHANNEL A PEAK B 1 442 Vp AS METERS 2 2 E EE EEEE oy m CHANNEL B n CHANNEL A CHANNEL A CHANNEL A CHANNELA A 3 a nalog AES A to D Peak Ranging pega Receiver a Converters Detectors Coupling q m bi CHANNEL B CHANNEL B CHANNEL B CHANNEL B Inputs E Analog Input Panel ME AAA a ee ee y ll y a Frequency References CHANNELA Digital CHANNEL A AC DC 11 000 kHz FREQUENCY Coupling METERS CHANNEL B CHANNEL B CHANNELA CHANNELA Detectors CHANNEL A Ranging RMS 1 005 V J LEVEL amp Fast RMS SNE METERS CHANNEL B CHANNEL B Detector Amplitude Settings References CHANNELA CHANNELA 7 CHANNEL A FUNC Highpass e a Detectors CHANNEL B LEV Filters ed H egning Ranging RMS Fast RMS gt 133 3 AC Coupling MEIS lers vs amp Q Peak FUNCTION Highpass Detect METERS ee etectors Filters Low Pass _ Weighting m Ranging RMS Fast RMS 74 053 AC Coupling Filters Filters a amp Q Peak CHANNEL B FUNC ChA Level CHANNEL A LEV CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B Measurement Function 2 CH RATIO Audio Analyzer Panel Figure 110 Conceptual Block Diagram Audio Analyzer 2 Channel Ratio Function Figu
216. d the data is loaded with the test but is not automatically graphed m Reprocess FFT data on zoom If this box is checked each time a Graph zoom is initiated for an FFT plot the data acquisition is re processed with an automatic Sweep Reprocess Data Ctrl F6 command Although this processing takes more time it assures that the plotted resolution is always the maximum supported by either the number of points graphed or by the FFT length See Retransforming and Reprocessing Data on page 157 and Zoom on page 286 Do not load panels on Open Test Normally when a test is opened all the instrument panels bar graphs and graphs are loaded on each page at the location and size that they were when the test was saved If this box is checked the instrument control settings including waveform amplitude frequency Analyzer instrument and function sweep settings and so on are loaded without changing the current panel and graph size and location Set Sample Rate when loading generator waveforms Most applications using arbitrary waveforms require that they be played back at the same sample rate at which they were created Audio Precision waveform files contain information on the design value of the sample rate If this box is checked ATS automatically sets the correct internal sample rate when a waveform file is loaded See Arbitrary Waveforms on page 91 and page 114 At the bottom of the page is the Company Name field where you can enter th
217. d Graph func tions which are discussed in Chapter 15 and Chapter 16 ATS 2 User s Manual 307 Chapter 18 Editing Data and Setting Limits The Data Editor The Data Editor Panel Figure 240 The Data Data Editor lolx Editor panel Digital Gener 1 Analyzer Leve 2 Analyzer Leve m 17 8218 kHz 15 2724 kHz E 143 0877 kHz W 11 2155 kHz 3 26190 kHz The ATS Data Editor is available by selecting Panels gt Data Editor from the Menu bar or by clicking the Data Editor icon on the toolbar E Columns Data Editor columns cannot be edited You cannot add delete move or rename a Data Editor column These columns correspond to the Source and Data settings in the Sweep panel to add or remove a column you must reconfigure the sweep The column width can be adjusted by dragging the column header de limiters with the mouse pointer Rows Data editor rows correspond to Sweep measurement points You may add or remove Data Editor rows Adding or removing rows changes the data in memory the graph and stored data files will reflect your modifica tions Data The settings and reading values shown in the Data Editor cells can also be edited Editing the value in a cell changes the data in memory and the graph and stored data files will reflect your modifications Data Display Typefaces The displayed values in the cells can appear in a normal typeface in a bold typeface and when limits are exceeded i
218. d audio equipment actual distortion is very low across most of the normal operating dynamic range and wide band noise dominates A THD N analyzer operates by removing the fundamental signal with a notch bandreject filter then measuring everything left over The left over signal in this case is the wide band noise and distortion products A THD analyzer makes highly selective amplitude measurements only at each specific harmonic product frequency The bandwidth of these selective measurements is so narrow that noise has almost no ef fect In such a noise limited case a THD analyzer such as Harmonic Distortion Analyzer may produce a much lower value than a THD N analyzer such as the Audio Analyzer in THD N functions Another difference comes about only when Ratio units dB X Y or ppm are selected Practical THD N instruments make a compro mise with the actual definition of distortion ratios in the interest of circuit economy The definition of THD and THD N ratios computes the am plitude of the distortion or distortion and noise products with reference to the amplitude of the fundamental signal component However practi cal THD N analyzers use the amplitude of the input signal including all distortion products as the reference instead of the fundamental compo nent alone At total distortion values of 10 0 and lower 20 dB and below the difference between these two approaches is negligible At higher distortion values t
219. d dragging sideways The mouse pointer changes from the standard arrow to a dragging pointer which indicates by a number whether you are dragging cursor 1 or cursor 2 When you have dragged the cursors off one another each cursor is assigned its own X axis display box ATS 2 User s Manual 289 Chapter 16 Graphs The Graph Options Menu a Audio Precision A A VIEW WAVEFORM Amplitude vs Time 1 114 V 1 114 Y 1 114 V 1 114 Y Figure 226 Graph Cursors on a deselected trace The cursors are shown as vertical lines whenever no Data traces are se lected To select a trace click on the corresponding row shown in the graph legend the legend row then appears highlighted to indicate that it is selected See Graph Legend later in this chapter on page 295 The se lected trace will be displayed as a thicker line and the cursors will be as signed to that trace displayed as crossed circles rather than vertical lines The crossed circles can be dragged along the trace with the mouse pointer To deselect a trace click the selected row a second time clicking in the Data or Axis cell When a trace is selected the Y axis values at both cursor intersections are shown in new display boxes at the left side of the graph A new display box also appears at the top of the graph showing the difference between the two cursor Y axis values You can also move the cursors on the graph using the keyboard When the graph window is selected click anywhere i
220. d in alternating bold and normal typefaces A bold typeface is used for odd numbered sets of traces a normal typeface is used for even numbered sets of traces m Data Editor scrolling The Data Editor automatically scrolls so that the set of data corresponding to the trace selected in the Graph Legend is shown at the top of its window ATS 2 User s Manual Chapter 16 Graphs 297 Chapter 16 Graphs Graphing invalid or suspect data 298 Graphing invalid or suspect data Not all readings can be displayed on the Graph panel A single point sweep for example returns only one data point This cannot be displayed on an ATS araph See Single Point Sweeps page 268 Invalid readings are skipped leaving a blank region in the graph Cur sors are restricted to regions of valid data If an entire trace consists only of invalid readings the message No Valid Data in Selected Trace will be dis played See Data Display Flags page 309 Occasionally Sweep Settling will time out before a final settled read ing can be made In such cases the unsettled data point is plotted but is flagged both in the Data Editor and on the Graph panel Timed out points are marked with a white T at the top of the graph above the plotted point See Timeout page 283 When regulation is used occasionally ATS s attempt to regulate the data will be unsuccessful In such cases the unregulated data point is plotted but is flagged both in the
221. d setup and so on Print Preview Click File gt Print Preview to view an on screen preview of your printed page You can zoom to different magnifications by clicking the Zoom buttons or by clicking the mouse pointer on the preview page Audio Precision APWIN A A FREQ RESP RIAA EQ at2c Figure 262 Print Preview Cri Next Page ena Iwo Page Zoom In Za Close Audio Precision A A EQ FREQUENCY RESPONSE RIAA Phono Preamp 36 25 00 15 38 44 ae LETH S ET ET 0 50 100 200 500 ik 2k 5k 10k 20k He responsa of a Phono preamp The Generator uses a addy fle lo agus he ppa ie Sclicra the RIAA preo emmphais curve Printing ATS Data as a Table You also have the option of printing the ATS data in a tabular format Click File gt Print gt Data The Data Editor will appear followed by the Print dialog box Click Print to print the table ATS 2 User s Manual Printing to a File Chapter 20 Printing and Exporting Audio Precision 07 08 02 14 41 53 File Name untitled Digital Generator Analyzer Analyzer Frequency Level A Level B 0 20 0000 Hz 10 000 dBu 10 000 dBu 1 199 990 Hz 10 000 dBu 10 000 dBu 2 200 000 Hz 7 000 dBu 7 000 dBu 3 1 99990 kHz 7 000 dBu 7 000 dBu 4 2 00000 kHz 13 000 dBu 13 000 dBu 5 20 0000 kHz 13 000 dBu 13 000 dBu COMMENTS Figure 263 Printing ATS Data in a tabular format Printing to a File You have the option of routing your print job to an HPGL or Postscript file rather tha
222. dB level adjustment to accomplish this when IEC468 Weighting and Q Peak are selected together m The F Weighting filter is based on psychoacoustic research and relates to typical human hearing sensitivity at a sound pressure level of 15 phons m CCITT Weighting and C message Weighting filters are essentially voice band filters sometimes required for telecommunications applications m The HI 2 Harmonic Weighting filter is available as a selection only when the Function meters are in THD N Ratio or THD N Amplitude functions The primary purpose of the HI 2 Harmonic Weighting filter is for rub and buzz measurements on loudspeakers This filter has a rising 12 dB octave response with the unity gain frequency four times higher than two octaves above the frequency of the THD N notch filter which means it emphasizes the effect of signals above the fourth harmonic and reduces the effect of signals below the fourth harmonic Maximum gain of the HI 2 Harmonic Weighting filter is limited to 28 dB m User Weighting provides a way to insert a custom weighting filter into the Function meter paths See User Filters below ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer The A EC 468 and F weighting filters are specified to 20 kHz at sample rates below 44 kHz their response within a few kilohertz of Fs 2 will deviate from specification Weighting filter responses are perfectly accurate at the following sample rat
223. digital codes The rms value of this sine wave is the full scale reference defined as 1 FFS or 0 dBFS Note that other waveforms noise or mu sic for example have different crest factors than a sine wave crest fac tor is the ratio of a signal s peak amplitude to its rms amplitude and will have different rms values at the amplitude at which their peaks just reach the maxima A consequence of defining full scale as an rms value is that high level signals that have a lower crest factor than a sine wave can display rms values greater than 1 FFS or 0 dBFS even though the digi tal maximum and minimum codes are not exceeded For example a square wave whose top and bottom are at the maximum digital codes will have an rms value of 1 414 FFS or 3 01 dBFS See Figure 286 FFS fraction of full scale simply the ratio of the rms value of the signal to the full scale value expressed as a decimal fraction A sinewave half the value of full scale would be indicated as 0 5 FFS The lower levels often en countered in practical audio applications may be displayed as mFFS milli fractions of full scale or FFS 1000 and wFFS micro frac tions of full scale or FFS 1000000 FS percent of full scale This is the FFS value multiplied by 100 For example a signal at 0 8 FFS is 80 FS dBFS decibels relative to full scale This is a logarithmic measurement defined as 20 log FFS For example a signal at 0 1 FFS equals ATS 2 User s Ma
224. diting Equalization Curve D Digital Gener 10 0000 Hz 13 0000 Hz 19 744 dBY 19 631 dBY 16 0000 Hz 18 0000 Hz 20 0000 Hz 22 0000 Hz 24 5000 Hz 27 0000 Hz 30 0000 Hz 33 0000 Hz 36 0000 Hz a Nrsc pre atsq Riaa pre atsq Files of type Eq Curve File atsq z File name 19 494 dBV 19 389 dBY 19 275 dBY 19 152 dBV 18 988 dBY 18 813 dBY 18 592 dBY 18 360 dBY 18 120 dBY 40 0000 Hz 45 0000 Hz 50 0000 Hz 17 790 dBV 17 369 dBV 16 943 dBV f Click the EQ Curve button to open the Equalization Curve dialog box then click the browser button to open the Equalization Curve file browser When you have selected an EQ file it will be attached to the generator panel and the file name will appear in the Equalization Curve dialog box 108 ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator The default amplitude data column is Column 2 you can choose another column from the drop down list in the Equalization Curve dialog box If you would like to view or edit the EQ file click the Edit button to open the Attached File Editor see page 313 You can create custom EQ curves by manually creating an ATS EQ file or by using the current sweep data in memory and a Compute function to produce an appropriate EQ file See Chapters 18 and 19 for more informa tion on saving data files and modifying EQ data from a sweep using Com pute functions Typical EQ Appl
225. duces faster measurements which can be impor tant when speed is at a premium as within a repetitive routine in an auto mated testing macro However you must know the probable range of the signal and set the fixed range maximum above the highest expected level Manual range selection is also preferred when listening to program mate rial such as voice or music on the built in loudspeaker or via the head phone jack Automatic ranging will constantly switch levels when a complex wide range signal is applied This may make it difficult to adjust a device for minimum distortion or noise for example ATS 2 User s Manual 129 Chapter 10 The Audio Analyzer The Function Meters 130 ATS 2 ranges are implemented in discrete steps When selecting a fixed range enter the maximum expected value into the Range field ATS 2 will select the next range which accommodates that value The Function Meters Figure 108 8 Analyzer Alla ES The Audio Analyzer Instrument Audi Analyzer Function Meters ChA input Analog ChB M o o y Ea 0 ala Range E Function a gt Measurement Function Amplitude Ch Ratio Crosstalk THD N Ratio THO N Ampl Bandpass SMPTE DIN Phase dBra 387 3 rei der B f287 3 rie Freq 00000 kHz wFs Ooo watts 8 000 Ohms d m E00 0 Ohms The Level meters examined previously display the rms amplitude of the signal applied to the Audio Analyzer The Function meters wh
226. e a nominally flat output from a device which contains a known equalization function Typical examples would be U S FM and TV aural broadcast transmitters using 50 us and 75 us preemphasis curves ATS 2 User s Manual Choosing an Analog Generator Waveform Chapter 8 The Analog Generator By attaching an equalization curve to the ATS 2 generator that is the in verse of the nominal curve used in the device under test the resulting mea sured output should be flat Small variations from flatness will be a measurement of the accuracy of equalization in the device since the atsq curves provided are accurate to better than 0 01 dB and the specified gen erator flatness is of the same order Squarewave Analog Generator Ta Ww Fri Square og Frequency 20 0000 kHz ii Figure 57 Analog Generator Squarewave Waveform Wfm Square The frequency range for squarewaves is from 2 Hz to 20 kHz The squarewave amplitude is calibrated in peak equivalent sinewave terms See Amplitude Control and Units on page 80 intermodulation Distortion IMD Intermodulation distortion IMD testing requires a stimulus which is a combination of two waveforms and a specific analysis technique to evalu ate interaction of the waveforms within the DUT ATS 2 provides two ver sions of the SMPTE DIN standard IMD test signals IMD signal amplitude is set in the Analog Generator Amplitude field The IMD composite waveform amplitude is calibrated in
227. e entered as digital or analog domain units with the V FS reference value being used to scale the references ATS 2 User s Manual 155 Chapter 10 The Audio Analyzer References 154 ATS 2 User s Manual The Spectrum Analyzer Figure 127 The Spectrum Analyzer panel EGRESS 5 x FFT Spectrum Analyzer Power spectrum only 1 0 00000000 0 00000000 Free Run Slope Psg 100 0 mFFS 100 0 mFFS 1 00000 kHz 1 000 Introduction The Spectrum Analyzer is a DSP instrument selection on the Analyzer panel It is named FFT on instrument browser lists and in OLE refer ences The Spectrum Analyzer is a general purpose waveform display and spectrum analyzer for ATS 2 It provides both m time domain oscilloscope display of waveforms and m frequency domain spectrum analyzer views ATS 2 User s Manual 155 Chapter 11 The Spectrum Analyzer Loading the Spectrum Analyzer The Spectrum Analyzer can analyze and display analog input signals up to 120 kHz with the optional high bandwidth ADCs and digital signals up to 108 kHz Features include large dedicated memory buffers flexible triggering av eraging techniques waveform processing selectable display methods a wide choice of FFT windowing functions and the capability of shifting a sinewave signal to a bin center for synchronous analysis This chapter examines each function control and display of the Spec trum Analyzer in detail If you are ne
228. e 18 for reference The field to the right of the Resolution field allows selection of u Law or A law compression This selection overrides the normal uncompressed word width selected in the left Resolution field which is grayed out un der these conditions Choose u Law or A law to enable the compression or Bits to return to normal linear PCM resolutions The Digital Generator outputs a 14 bit or 13 bit signal when the Resolution is set to u Law or A Law Dither if enabled is properly scaled to these word lengths ATS 2 User s Manual 55 Chapter 7 The Digital I O Panel The DIO Output Section See the sidebar on u Law and A law below for more information on these companding techniques p Law and A Law The International Telecommunication Union ITU specifies in its standard G 711 two similar approaches for reducing the bit rate in digi tal voice telephony Called u Law and A Law these techniques have been widely used in digital telecommunications for a number of years u Law and A Law are known as companders converting 14 bit lin ear PCM samples u Law or 13 bit linear PCM samples A Law to an 8 bit pseudo floating point representation via compression at the en coder and expansion at the decoder ATS 2 can both transmit and receive u Law and A Law encoded digital signals through the AES3 IEC60958 3 and optical inputs and outputs Preemphasis Figure 19 The DIO Preemphasis Pre emphasis Off selections ma S
229. e Audio Analyzer DSP analog sig nals are first digitized by precision ADCs selected on the Analog Input panel before being sent to the Audio Analyzer To select digital input connectors digital input format and configure other aspects of the serial interface go to the DIO panel see Chapter 7 ATS 2 User s Manual 125 Chapter 10 The Audio Analyzer The Level Meters 126 To select analog input connectors range coupling and ADCs go to the Analog Input panel see Chapter 6 You will notice that as you select Digital or Analog the appearance of the Audio Analyzer panel changes as well displaying a different set of settings units and references The Level Meters if Analyzer Oo x Instrument Audio Analyzer ChA Input Analog ChB ME Level A Fea al Range lv La gt Function Measurement Function 4mplit Til Rangel Det Auto ans Bue 10 Hz Fsr2 Flt None a Two Level meters are located near the top of the Audio Analyzer panel one for each input channel The Level meters display the audio am plitude of the input signals These meters are true rms instruments using the normal or the fast rms detector as selected in the Detector Det field lower on the panel Figure 105 The Audio Analyzer Level Meters The meter detectors are discussed in more detail on page 141 Note Detector choices affect both the Level meters and the Function meters
230. e Meters Below the Frequency meter displays are panel sections labeled Har monic Sum 1 and Harmonic Sum 2 Each section contains a meter dis play and control fields for input channels A and B for a total of four Harmonic Sum meters Each meter consists of the digital display a Ra tio unit checkbox and controls for selecting the harmonic orders that the ATS 2 User s Manual Harmonic Distortion Product Amplitude Chapter 14 The Harmonic Distortion Analyzer meter will measure The meter display has the usual ATS selections of am plitude units When the Ratio units box is checked the meter will display in units of dB X Y or ppm referenced to the fundamental amplitude Harmonic Order Control The rows of numbers below each Harmonic Sum meter provide the means to select the harmonics the meter reads The upper row of numbers selects the even harmonic orders through the fourteenth 2 4 6 8 10 12 and 14 The lower row selects the odd harmonic orders through the fifteenth 3 5 7 9 11 13 and 15 You can select or deselect any harmonic order by clicking on the number of the or der Clicking the checkbox at the beginning of a row selects or deselects the entire row of harmonic orders When only one harmonic order has been selected for a particular meter the display in the meter is the amplitude of the specific harmonic signal se lected For example clicking 3 in the lower row causes the associated dis play to conti
231. e Reference 2 96 Frequency Reference 2 00 5502 96 Watts Reference 0000 2 ee eae 96 dBm Reference 0000 bee eee 96 Chapter 9 The Digital Generator 99 Test Signal Generation in ATS 2 99 Two Audio Signal Generators 99 Signals for Digital Measurements 99 The Digital Generator Panel 100 Frequency Units 0 20052 101 Output On Off and Channel Selection 101 Auto ON 000 eee ee ee ee 101 Channelinvert 0 00502 a 102 Amplitude Control and Units 102 Choosing a Digital Generator Waveform 103 Sine waveforms 005050 e eee 103 Wfm Sine Normal 2 0005 104 Wfm Sine Var Phase 2 2500s 104 Wfm Sine Stereo 2 002 ee a 105 Wfm Sine Dual 2 2 2 2 2 2 2 2 22 284 105 Wfm Sine Shaped Burst 2 106 Wfm Sine EQ 0 000 eee ee ee 107 Wfm Sine Burst 2 2 2 02 2 2 2 2 2 2 808 109 Wfm Sine Offset 2 2 0008 eee 111 Intermodulation Distortion IMD 112 Wfm IMD SMPTE DIN 4 1 08 112 Wfm IMD SMPTE DIN1 1 08 112 Squarewave 0 00 eee ee ee eee 112 Wfm Square oaa a a a a a a a 112 White Noise a a a a a a a a a eee eee 113 Wfm Noi
232. e analog and one digital ATS 2 has one analyzer that must be switched between analog and digital domains This means that in any test only one Cascade analyzer can be mapped to the ATS 2 analyzer This decision is made on the basis of the settings saved in the test s Bar Graph or Sweep panel settings since these reflect the way the test creator was using the instrument These rules are used m If all the Bar Graphs in the Cascade test are attached to Cascade s Analog Analyzer the Analog Analyzer controls will be mapped to the ATS 2 Audio Analyzer m If all the Bar Graphs in the Cascade test are attached to Cascade s Digital Analyzer the Digital Analyzer controls will be mapped to the ATS 2 Audio Analyzer ATS 2 User s Manual 421 Appendix F Test and Macro Translators The Macro Translator 422 Bar Graphs that are attached to neither Analyzer are not considered m If no Bar Graphs are attached to either Analyzer or if Bar Graphs are attached to both Digital and Analog Analyzers the translator will check the Cascade Sweep panel Data 1 field If Data 1 is attached to the Analog or Digital Analyzer the controls of that Analyzer will be mapped to the ATS 2 Analyzer controls a If Data 1 is not attached to either Analyzer the translator will continue checking Data 2 through Data 6 in a similar fashion m If no Bar Graph or Sweep Data field indicates an Analyzer domain the Cascade Analog Analyzer will be mapped to the ATS 2 An
233. e and other information and a 3n byte payload where n is the number of samples in the waveform Each sample is quantized to 24 bits and is in the range 1 1 2 3 ATS 2 User s Manual MATLAB support Appendix E AP Waveform File Support ap write wave accepts both filenames and file handles If a filename is supplied any extension is replaced with agm or ags depending on the size of the data matrix ap write wave closes the file when the function exits If a file handle is supplied ap write wave appends to the file leaving it open on exit sample rate a scalar is the sample rate of the waveform in hertz If normalize is 1 the data is scaled so that the peak of the waveform reaches full scale The data is also dithered before reducing the word size to 24 bits This preserves low level information and eliminates harmonic distortion due to quantization This mode is recommended unless multiple waveforms are being generated whose amplitude relative to one another is important If normalize is O the data is written to the file unscaled If any sam ples are outside the allowable range they are clipped and a warning is is sued data is a matrix containing the waveform If the smaller dimension is 1 a mono waveform file is generated If it is 2 a stereo waveform file is gen erated Any other size will generate an error Example At a sample rate of 40 kHz create a sinewave of approximately 1 kHz in channel A and noise in cha
234. e balanced signal is available on the XLR male connector with pin 2 wired to the high leg of the signal pin 3 to the low and pin 1 to ground In balanced mode the BNC connector for that channel is discon nected When an output is set to unbalanced the signal is available at both the XLR male connector and the BNC connector simultaneously In this config uration pin 1 of the XLR is wired to ground the BNC shell and pin 3 of the XLR are held to the unbalanced signal low and the center pin of the BNC and pin 2 of the XLR carry the signal high 36 ATS 2 User s Manual The Analog Inputs Chapter 4 Signal Inputs and Outputs Do not unbalance the balanced outputs by connecting pin 2 or pin 3 of an XLR output connector to ground as might be done with adapter cables Connecting the ATS 2 balanced outputs to an unbalanced load will produce distorted waveforms Use the unbalanced output connectors for an unbalanced load The common mode test signal is applied to both pins 2 and 3 of the XLR connector while pin 1 is grounded The BNC connector is discon nected in the common mode configuration Three impedance configurations are available for the ATS 2 at the time of ordering Changes in impedance configurations must be performed at the factory or by an authorized Audio Precision representative a Standard Impedance Configuration With the standard impedance configuration output impedances can be set to 40 Q or 150 Q in the
235. e buttons Se lecting Pos causes triggering to occur on a positive going portion of the trigger source signal while Neg causes triggering on a negative going waveform ATS 2 User s Manual Triggering Chapter 11 The Spectrum Analyzer Triggering with Synchronous Averaging Synchronous averaging which depends on the precise alignment of many acquisitions requires careful consideration of triggering techniques See Synchronous Averaging on page 167 Without Re alignment If synchronous averaging without re align mode is used proper trigger ing is absolutely essential Random untriggered acquisitions will not be aligned in time resulting in cancellation of coherent signals and large am plitude errors In stimulus response testing from ATS 2 either the Analog Gen or Dig ital Gen as appropriate FFT trigger sources should be used If an exter nal signal is presented from another signal source one of the ChA or ChB selections should be used as trigger source If signals are being acquired on both channels without re align they must be at the same frequency or must have harmonically related frequen cies Sync without re align will properly measure only signals harmonically related to the trigger source A signal whose frequency is not related to the trigger source may have large amplitude errors or may entirely disappear With Re alignment The re align mode should be used for accurate amplitude measurements on all signals abo
236. e floor than RPDF dither but it imparts no noise modulation effect to the audio Triangular dither can add or subtract up to one LSB peak amplitude at the selected resolution Rectangular Rectangular probability distribution function RPDF dither provides a better signal to noise ratio than triangular dither but suffers from noise modulation effects Rectangular dither can add or subtract up to one half LSB peak amplitude at the selected resolution m Shaped Shaped dither is TPDF dither shaped through a filter resulting in a dither signal with a rising 6 dB per octave slope set with the O dB effect point at one half the sampling rate This places most of the dither power at higher frequencies where much of the resultant noise falls out of band for most devices and where audibility is lower m None No dither is applied Certain generator waveforms such as Monotonicity J Test Walking Ones or Zeros and Random waveforms are only usable with no dither When one of these waveforms is selected dither is automatically disabled and the Dither Type field is not available ATS 2 User s Manual 121 Chapter 9 The Digital Generator Digital Generator References 122 Digital Generator References With the appropriate choice of units amplitude and frequency settings in the Digital Generator can be made relative to reference values These ref erences are entered manually in the Digital Generator References area Figure 100 Digita
237. e information in the ASCII version of an AP data file fj ATS 2 adx Notepad File Edit Search Help untitled 61 26 62 14 61 21 Digital Generator Frequency Analyzer Level A Analyzer Level A Analyzer Level A Data 1 Data 2 Data 3 9 99999999713 9 99999999713 10 0000000029 9 99999999713 9 99999999713 10 0000000057 6 99999999713 6 99999999713 7 00000000287 6 99999999426 6 99999999426 7 00000000574 12 9999999971 12 9999999971 13 0000000029 12 9999999943 12 9999999943 13 0000000057 Figure 245 ASCII version of an AP data file ATS 2 User s Manual 315 Chapter 18 Editing Data and Setting Limits Setting Limits 316 ATS 2 User s Manual Chapter 19 Performing Computations on Data Chapter 19 Performing Computations on Data Chapters 15 16 and 18 explain how ATS 2 can gather display edit and perform other operations on a set of data Using the commands on the Compute menu you can also process the current data in memory with a number of mathematical algorithms Use of the Compute algorithms does not change the acquisition of data Instead the acquired data points are changed according to the applied al gorithms by averaging for example or inversion or normalization The Compute algorithms irrevocably change the data in memory Save the original data on disk if you wish to keep it See Comparing Computed Results with Original Data page 327 ATS provides 10 different computations w
238. e name you would like to appear on ATS graphs If a name is en tered here you have the option enabling or disabling screen or print dis play in the Graph Label dialog box or in the Page Setup dialog box ATS 2 User s Manual 363 Chapter 25 Configuration and the Utilities Menu The Configuration panel Log Figure 280 The Log System Status and Information Configuration tab The Log File The log file is an optional record of many important ATS operations in cluding test names date and time of each running of tests limits failures file loading and saving activity and error messages New information is ap pended to the log file so a log file can become a complete record of an en tire audio testing procedure The log file is a standard ASCII text file readable by text editors such as Windows Notepad and other applications A log file has the extension alg FAIL 69 25 01 16 69 38 Execute sweep C ATS Log Limsweep ats2 Failed Upper 8 Lower 6 Timeouts 6 UnRegulated 6 BadData 6 Analog Generator Frequencuy Hz Analyzer Amplitude A 566606 13 538827277 gt 30 36656 6 26895629521 gt 15 99660696 26858 4 71412875609 gt 5 346 5 8 0116795131327 gt 3 2789288 25H 8 0225582941998 gt 10 1860295 _ 186 175 B 0421745019645 gt 18 0698889 136 45 8 599749184736 gt 26 1677627 100 7 9648988702 b 34 2759719 Figure 281 A typical ATS log file showing test file name and path date and t
239. e provided on the Audio Precision Resources Disc and are also available for download from our Web site at ap com You can use the test samples as examples or as starting points for your own custom tests The Log File ATS can generate a log file which can contain error messages file activ ity sweep activity graph information and pass fail test results The log file can be viewed on the screen or printed The extension for the log file is m AP log file alg The log file is enabled and set up on the Configuration panel and is dis cussed in detail in Chapter 25 Keyboard Shortcuts Many of the ATS Menu and Toolbar commands are also available as keyboard shortcuts The Sweep Start command for example is F9 the Analog Generator panel can be brought to the screen with Ctrl G Keyboard shortcuts are identified in the chapters which discuss the func tions they command and are listed as alternative commands in the ATS menus They are all listed here as well Function Keys F1 Help Context sensitive Help brings the Help topic associated with the currently selected panel feature to the screen F2 Resets Min Max In a Bar Graph resets the minimum maximum value history F2 Edit In the Data Editor enables editing within a data cell F3 Set Gen Ampl Ref Sets the Analog Generator dBr reference value to the current Analog Generator amplitude setting Ctrl F3 Set Gen Freq Ref Sets the Analog Generator frequency r
240. e rate a trigger point a time vector and the waveform vector The sample rate and trigger point are deter mined from the header information in the waveform file For acquired waveforms the trigger point is the sample at which the trig ger occurred during acquisition For generated waveforms such as arbi trary waveforms created by the Multitone Creation utility in ATS 2 the trigger point is usually zero The time vector is constructed from the trigger point the total number of points in the waveform and the sample rate The data vector consists of the file payload converted to double If ap read wave determines that the file contains data acquired from an analog source it attempts to scale the data so that the value of a sam ple represents the analog voltage at that time Because some gain con stants are known only to the hardware on which the waveform was acquired however this will only be approximate Data originally from a digital source is not scaled ATS 2 User s Manual MATLAB support Appendix E AP Waveform File Support Example Read the ags file generated by the ap write wave example This returns a 1 x 2 structure array Typing waves 1 at the prompt re turns ans sample trace 10000 nd ger Poan time 2048x1 double data 2048x1 double The data can now be examined figure 1 plot waves 1 time waves 1 data figure 2 plot waves 2 time waves 2 data ATS 2 User s Manual 415
241. e rate at sample rates above approximately 44 kHz As sample rates decrease toward twice the corner frequency of the selected filter it essen tially becomes the same as the Fs 2 selection You can also use a custom lowpass filter file by selecting User LP See User Filters page 147 The Fitr Field The field labeled Fltr just beneath the bandwidth filter fields has dif ferent operations in different functions of the Function meter m In the Amplitude 2 Ch Ratio and the two THD N functions this field allows selection of weighting filters as discussed below In the Bandpass function the field permits selection of whether the bandpass filter is tuned to the fundamental frequency of the source being tracked or to the 2nd 3rd 4th or 5th harmonics See BP BR Filter Tuning on page 149 m In the Crosstalk SMPTE DIN and Phase functions the field disappears Fitr Weighting Filters Figure 121 The Audio Analyzer Det Auto RMs BP ER Fitr Freq Fltr selections Bw lt 10H Fef Sweep Track Fltr Mone dEr A Weighting IE C48 Weighting Fed F Weighting CCITT Weighting wa L Meszage Weighting Hl Harmonic weighting User Weighting Weighting filters provide response curves which are relevant to the char acteristics of human hearing Weighting filters are frequently required for meaningful noise measurements and sometimes for THD N as well Stan dards often specify weighting filters f
242. e to be applied to the DUT which ATS 2 User s Manual 107 Chapter 9 The Digital Generator Choosing a Digital Generator Waveform is the value entered in the Amplitude field corrected by the value at that frequency of the correction factor in the attached EQ file When Sine EQ is selected the values in the Amplitude field are displayed in blue rather than black To set the output amplitude you can enter a value in either the Ampli tude field or the Post EQ field and the value in the other field will be properly adjusted according to the correction factor The Digital Generator will not permit an output amplitude entry greater than 1 000 FFS 0 dBFS If the value of the normal pre EQ Amplitude field as modified by the equalization file would produce an amplitude greater than 1 000 FFS an error message is displayed If a frequency value outside the frequency range span of the EQ file is entered on the generator panel or occurs during a sweep the Post EQ am plitude will go to O FFS Specifying the EQ Curve The EQ curve is specified by an ATS data file usually an EQ file with the extension atsq which lists frequencies in Column 1 and the corre sponding amplitude changes in Column 2 or another column of your choice Equalization Curve Digital Generator Frequency Column 2 Analyzer LeveB y Edit OK Cancel E AeA AY e IEC60958 3ijittertolerance atsq aa Riaa de atsq Figure 84 EQ file attachment and e
243. e typical device transients tend to fall off in an exponential fashion this can be a very useful settling algorithm especially for analog signals m Flat Flat provides highly repeatable results but often requires more settling time than Exponential Flat is the default algorithm selection ATS 2 User s Manual Sweep Settling Chapter 15 Sweeps and Sweep Settling m Average Average is useful for noise measurements and for other random or aperiodic signals The algorithms look to the Settling panel for values to use in making their evaluation of signal settling Average uses only the Points value Ex ponential and Flat also look to the values set in the Tolerance and Floor fields As mentioned in Settling Delay Time above all measurements taken during the initial Delay period are discarded before ATS begins evaluating the signal with any of the selected algorithms Exponential Settling Algorithm The Exponential Algorithm reports a data point after a certain num ber of readings the value set in the Points field fall within an exponential settling criteria envelope an example of which is shown in Figure 222 The shape and calibration of this envelope are determined primarily by the value set in the Tolerance field The Floor field which is explained be low keeps the size of the envelope from decreasing to zero as the value be ing measured becomes very small 16 8 4 2 1 Envelope Centering Yy 1 de
244. e with Fast RMS the measurement continues until the next positive going zero crossing of the signal cycle Normally Auto will be your best choice with the most important excep tion being noise measurements discussed below The Auto algorithm takes into account the signal frequency being measured and whether or not the bandpass filter is in use and then selects the fastest reading rate which will deliver the specified accuracy under these conditions For noise measurements the 4 s selection is recommended to provide integration of noise over a longer period You might also choose 4 s when measuring periodic waveforms for the best accuracy and repeatability at very low frequencies The 8 s 16 s 32 s 64 s 128 s and 256 s choices provide progres sively faster measurements If you are watching a bararaph display while making adjustments to a DUT for example the faster rates better approxi mate real time readings and will give you better feedback However low frequency measurement accuracy is reduced at faster rates Each step faster in reading rate raises the low frequency limit to accu rate measurement Faster reading rates are also less tolerant of noise in the signal The Bandwidth and Filter Fields Beneath the detector fields are three fields which allow selection of vari ous filter options for the Function meters The first two are labeled BW for bandwidth and consist of highpass and lowpass filter options The third
245. early readings and then calculates when a reading should be considered stable enough for data to be acquired The Settling panel offers two independent controls to accomplish this for each ATS meter the Settling Delay time and the Settling Algorithm selec tion Settling Delay Time The first task in settling is to ignore all early readings Any measurements which arrive within the period between the beginning of a sweep step and the time set in the Delay field are discarded Typical default Delay settings are in the 20 ms to 100 ms range depend ing on the instrument selected The Delay value is independent of the Algorithm choice and is effec tive even if the Algorithm selection is None To disable the sweep settling delay for a particular instrument enter 0 00 as the value in the Delay field For Time Sweeps where it is desired to make as many measurements per second as possible the Delay value should be set to 0 00 and the Al gorithm selection should be None All settling functions must be disabled when performing an External Sweep which has a continuously moving independent variable a glide sweep See Some Hints on page 276 Algorithm Selection In addition to setting a Delay time you can also select one of three or None Settling Algorithms to evaluate the stability of your signal The three Settling Algorithms are u Exponential Exponential usually provides consistent results in the minimum length of time Sinc
246. eate a new list of frequencies in Multitone Creation Utility click OK instead First the current test is saved as Makewave tmp Then you are pre sented with the following dialog box ATS 2 User s Manual Creating Multitone Waveform Files Chapter 13 The Multitone Audio Analyzer Choose File gt Open from the ATS Main menu and select the test or data file which has the information you want in it and then click Con Figure 199 ATS Multitone Open File dialog box tinue Macro Go to Editing the Frequency list below File Options Figure 200 ATS 2 Multitone Creation Utility Supporting File Creation Options ES Supporting File Creation Options dialog Data File s containing Frequency box M Amplitude and Phase information 4754 ASCII Data file s containing Frequency M Amplitude and Phase information AT Se e ASCII Waveform statistics file s FS e ASCII Sweep Table statistics file s STS e Retain 46M files when making Stereo files The File Options button opens the Supporting File Creation Options dia log box which offers the following options m Data File s containing Frequency Amplitude and Phase Information atsa In addition to the agm or ags generator files and sweep table files this option specifies the creation of an Audio Precision data file a ASCII Data file s containing Frequency Amplitude and Phase Information atsx This is an ASCII text file containing the same
247. ecting the data for the graph display the Sweep panel also sets the graph scaling and calibration that is the number and spacing of the vertical and horizontal graticule lines and the X axis and Y axis numeri cal calibration and unit domain To change these graph parameters you must go to the Sweep panel To view the graphed data in a tabular format go to the Data Editor This chapter discusses the display controls available on the Graph panel The Graph Panel The ATS Graph panel is available by selecting Panels gt Graph from the Menu bar or by clicking the Graph icon on the toolbar The Graph panel plots the Source and Data information provided by the Sweep panel as X Y relationships and provides a number of controls to modify the display examine the traces with cursors and add labels com ments and descriptive legend information to both the screen display graph and exported or printed versions of the graph ATS 2 User s Manual 285 1m 2m 3m 4m ereer roe Joso unesye foso vs orreri Yellow ts Sai E i 4 FFT ChA Amplitude Left Be s Green w Solid 1 FFT ChB Amplitude Right FFT is used to display a time sample of the D converted signal waveform Press the Sweep Spectrum Yaveform button for the frequency domain 4 The Graph panel itself can be resized to any practical dimension or as pect ratio you prefer by dragging the borders with the mouse pointer Simi larly the Legend and Comment areas
248. ection of harmonic distortion products from the 2nd through the 15th The Harmonic Distortion Analyzer uses FFT techniques to isolate and measure each harmonic The FFT bins are very narrow and measure ATS 2 User s Manual 245 Chapter 14 The Harmonic Distortion Analyzer Introduction ment of residual noise is almost entirely excluded This means that the Harmonic Distortion Analyzer can measure harmonic distortion with out noise for any specified set of harmonic products If all the harmonics are selected the Harmonic Sum meters read THD Total Harmonic Dis tortion without noise Even though it is internally based on FFT technology the Harmonic Distortion Analyzer effectively operates as a real time program The analyzer drives constantly updating panel meters and its results can be displayed on bararaphs or plotted as traces on a graph See Appendix C for more information on FFTs The Harmonic Distortion Analyzer will accept either digital or ana log domain audio input signals as selected by the Input field at the top of the panel It is a two channel instrument capable of performing mea surements on both channels of a stereo signal at the same time For an analog signal the Harmonic Distortion Analyzer can measure a fre quency range from dc to half the converter sample rate F 2 set on the Analog Input panel for digital signals the Harmonic Distortion Ana lyzer can measure a frequency range from dc to half the signal samp
249. ectrum view uses this time domain acquisition synchronous averaging is also useful for frequency domain views With synchronous averaging and time alignment via proper triggering or the Sync re align mode coherent components will be unchanged by the averaging process The average value of noise components will be reduced by 3 dB for each doubling of the averaging factor Figures 140 and 141 show the same signal conditions but Figure 141 has been averaged over 128 acquisitions using synchronous averaging Note that the peak to peak variance of the noise is still approximately as it was with no averaging but the average level of the noise is now approximately 180 dBV This low ered noise floor makes clearly visible a 9 kHz distortion product another peak at 12 kHz and the hint of another at 6 kHz ATS 2 User s Manual 171 Chapter 11 The Spectrum Analyzer Averaging 100 120 140 160 1860 OL A Figure 141 Low level signal viewed in the frequency domain averaged with 128x synchronous time domain averaging Average noise level is reduced from noise level shown in Figure 140 with no change in noise variance Power Spectrum Averaging Spectrum averaging operates only on the frequency domain amplitude vs frequency results following an FFT It will not operate if a time domain display FFT Time at Source 1 has been selected The primary purpose of spectrum averaging is to provide a more accu rate measurement o
250. ed ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator Zero Crossing The beginning and ending of any tone burst are always at the posi tive going zero crossing points of the sinewave which eliminates transients from the output Because of the zero crossing nature of the tone bursts only integer num bers of cycles can be entered as a Burst On or Interval setting if you are using s B units only time durations which represent multiples of the full pe riod of a cycle of the selected sinewave can be entered as a Burst On or Interval setting Wfm Sine Offset Figure 87 Digital Generator Digital Generator Sine Offset wire Sine Offset Frequency 997001 kH m Cha ChB Offset fo 000 FFS E inet FFS El Amplitude ak FFS This waveform is a combination of a sinewave with a digital DC signal Digital DC is essentially the same digital code sent for every sample see Wfm Special Constant Value on page 120 The frequency of the sinewave for the Sine Offset waveform like the other Digital Generator sinewaves can be set in the range of 2 Hz to 50 of the sample rate the sinewave level is set in the Amplitude field s The digital DC signal amplitude which can have a positive or negative value is set in the Offset field The sum of the sinewave and DC ampli tudes may not exceed positive or negative full scale FS If the sinewave amplitude is O FS the
251. ed dither is visible in the averaged result but not on any single acquisition and FFT Coherent signals very near the noise floor such as the distortion product at 9 kHz in Figure 142 may become visible as the noise converges to its average value Spectrum averaging is selectable in the field to the right of the Avgs la bel as Power spectrum only If a time domain view is selected following a spectrum averaging process the Reprocess Data command Ctrl F6 must be used to view the time domain data rather than the Transform Data w o Acquire F6 command Only the last acquisition of the series of averaged acquisitions will be viewed See page 157 for more information Display Processing Waveform time domain Display Processing Four modes are available in the Spectrum Analyzer for processing the amplitude versus time relationship of a sampled signal before displaying the waveform These modes are applicable only to time domain oscillo scope views and have no effect on frequency domain FFT spectrum analy sis VIEWS ATS 2 User s Manual 175 Chapter 11 The Spectrum Analyzer Display Processing 174 The display processing setting determines how the data is modified for display when the spacing of the sweep points is different from the spacing of sample points in the acquisition The four modes available in the Wave Display field are m Interpolate m Display Samples Peak Values and Absolute Values Interpolate
252. ee Figure 27 for reference The Voltage field displays the input amplitude of the serial digital inter face signal Serial digital interface signal voltage is measured in volts peak to peak Vpp The Voltage field does not display when Optical is se lected as the digital input Format The serial interface input voltage may be used to control a sweep as part of a test by selecting Dio as the instrument and selecting the reading Input Voltage at Source 1 or Source 2 on the Sweep panel ATS 2 User s Manual 63 Chapter 7 The Digital I O Panel The DIO Input Section 64 Input Resolution Figure 28 The DIO Resolution selections Resolution 24 E El its De emphasis OFf Scale Freg by The actual resolution or word width of the incoming digital signal is shown in the Active Bits display below The Resolution field shows the resolution or word width to be en forced on the incoming digital signal You can set the resolution to any inte ger value from 8 bits to 24 bits by typing in the value and pressing the Enter key If the value entered in the Resolution field matches or exceeds the reso lution of the incoming digital signal the signal is passed on unchanged If the value entered is lower than the incoming resolution the signal is trun cated at the LSB The value of quantization noise and distortion of the audio of digital in put signals measured by the Analyzer instruments will be affected by the In put Resoluti
253. eference value to the current Analog Generator frequency setting ATS 2 User s Manual 27 Chapter 2 The ATS Control Software Keyboard Shortcuts 28 m F4 Set Analyzer Ampl Ref Sets the Audio Analyzer and the Harmonic Distortion Analyzer dBr reference value to the current Analyzer amplitude reading Ctrl F4 Set Analyzer Freq Ref Sets the analyzer frequency reference value to the current value displayed in the analyzer frequency counter F6 Re Transform without Acquire for FFT based batch mode instruments Spectrum Digital Interface and Multitone Analyzers Performs a new transform on the acquired data and graphs the results Ctrl F6 Re Graph without Transform or Acquire for FFT based batch mode instruments Spectrum Digital Interface and Multitone Analyzers Graphs the transform results currently in DSP memory without performing a new transform F7 Graph or Re Graph Graphs the data currently in computer memory Alt F8 Store in Graph Buffer Stores the present trace or traces to the Graph Buffer memory F8 Display Graph Buffer Displays the trace or traces currently stored in the Graph Buffer memory Ctrl F8 Clear Graph Buffer Deletes any trace or traces in the Graph Buffer memory F9 Sweep Start Go Starts a new Sweep equivalent of Sweep Start or clicking the Go button Ctrl F9 Sweep with Append Starts a new Sweep while retaining previous data appending the new sweep to the old equi
254. eform Views 191 Interface Waveform 2 0 005 eee 191 Eye Pattern 192 Jitter Waveform 00002 ee eee 193 Digital Interface Analyzer Spectrum Views 195 Interface Soectrum 2 20000 ee eee 195 JitterSpectrum 0 000 eee eee 195 Digital Interface Analyzer Histograms 197 viii ATS 2 User s Manual Interface Amplitude Histogram 197 Interface Pulse Width Histogram 198 Interface Bit Rate Histogram 199 Jitter Histogram 2 2 002004 200 InterVuMenu atsb 2 2 2 2 0 2 002 eee ee 201 Digital Interface Analyzer panelsettings 202 Wave Display processing Time Domain view only 202 Interpolate 0 000 ee ee eee 203 DisplaySamples 2 080 505 ee 203 Peak Values 0000 eee eee eee 204 Eye Pattern 204 Jitter Detection 02 2 2 00484 204 Squarewave Converter Clock Jitter Detection 206 Averages spectrum view only 207 FFT Windows for the Digital Interface Analyzer 207 Trigger Source 2 002 eee ee ee 209 Triggering for squarewave acquisitions 210 Trigger Slope 2 002 eee ee ee ee 210 Data Acquisition 002 0502 eee 211 Receive Error Triggers 208 211 References oaoa aa a a a a a a a a a a a 211 Saving and Loadin
255. eform to be generated instead it passes the digital audio signal connected to the rear panel SYNC REF IN BNC connector through to the Digital Generator output ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator Since the sample rate at the Digital Generator output is set at the DIO OSR this is a convenient way to synchronize an external test signal with ATS 2 You can also use Pass Thru to convert an external signal from one sample rate to another as might be necessary when working at a 48 kHz sample rate but using a Compact Disc with test signals at a 44 1 kHz sam ple rate as a source The REF IN signal sample rate must be between 28 8 kHz and 108 kHz The ratio between the OSR and the REF IN signal sample rate is calculated by ATS and a sample rate converter is used to maintain the output audio frequency at the REF IN audio frequency value The Digital Generator output signal is then synchronized and frame synced to the con verted REF IN signal Additionally the ratio of the REF IN sample rate to the OSR must fall in the range between 1 3 to 3 1 or stated another way OS lt REF INSR lt OSR x3 The range of the OSR is 28 8 kHz 108 kHz To avoid attenuation and distortion in Special Pass Thru the REF IN audio frequency must not exceed 0 47 x OSR If the REF IN signal is stereo the output signal will also be stereo Sta tus bytes are not passed through to the output but are set on t
256. either case once you have chosen a EQ Source you must then se lect which data trace in current memory and which data column from the EQ Source you wish to use Compute Equalize interpolates between data points in the EQ Source data as necessary to produce Y axis values precisely at the speci fied X axis values Compute Status The Compute Status command on the Compute menu brings up the Compute after Sweep Status panel which lists all the Compute operations you have selected to Apply After Sweep ATS 2 User s Manual Clear All and Reset Chapter 19 Performing Computations on Data The list shows the order in which the computations will be performed This initial order is determined by the order in which you have set up and enabled Compute operations and set them to Apply After Sweep Compute after Sweep Status Computes Data Add amp Target 1 000 Vo Honz 1 00000 kHz Start 150 000 Hz Stop 12 0000 kHz Start 15 0000 Hz Stop 18 0000 kHz Start 555 000 Hz Stop 8 25000 kHz Clear List Figure 258 Compute Status Dialog Box You can add new Compute operations to the list change the order of the computations and clear the entire list Note that the Compute After Sweep Status list shows only those Com pute operations which have their Compute After Sweep checkbox checked Adding a Compute operation from within the list sets the checkbox in the specified operation panel Clicking the Clear List button does not clear
257. en generator frequency and measured high pass filter output amplitude on the attenuation skirt Normal The assumption for Normal is that any change in the Regulation Source parameter will cause an inverse proportional change in the regulated Target parameter This is the normal relationship between generator frequency and measured low pass filter output amplitude on the attenuation skirt or between generator amplitude and measured THD N in relative units dB or in the lower noise limited range of a DUT Maximum Maximum regulates in search of a maximum or peak value steering the Source parameter to find the peak ATS 2 User s Manual 357 Chapter 24 Regulation e Minimum Minimum regulates in search of a minimum peak value steering the Source parameter to find the minimum peak m Stepsize 358 The Stepsize field controls the initial size of the increments which will be made to the regulation Source parameter When the regulated parameter reading first passes beyond the Target value the actual step size will be decreased and the direction of change reversed as the algorithm goes into a binary search mode to determine the final value to regulate the measurement Stepsize may be set in a number of ratio units including X Y and dB The optimum value for Stepsize depends upon the DUT and the distance to the Target value from the initial starting value Large steps will reach and pass the Target rapidly but more iterati
258. en the two formats See page 386 for more information about Channel Status The ATS Status Bits panel gives you the ability to both view received sta tus bits and to set transmit status bits to any condition Choose Panels gt Status Bits to open the panel or click the Status Bits button on the Toolbar or on the DIO panel ATS 2 User s Manual The Status Bits panel Chapter 7 The Digital O Panel Status Bits Digital 1 0 Receive A Receive B Mode Professional Mode Normal C Non Audio Audio Mode METE Audio Mode PTE iad D Coic Emphasis None 7 E j gt Freg Mode Locked q P Sample Freg Hot Indicated Channel Mode 2 Channel Sample Freg Not Indicated Channel Mode Nat Indicated Category Code General Channel Mode Not Indicated l User Bits None Source Mum Don t care User Bits None ee ae Ausiliary Bits 20 bit not define Channel Mur Don t care Ausiliary Bits 20 bit not defi Sudio Word Ler Not indicated Sample Freq 441 kHz Audio Word Len Nat Indicated Ref Signal Mat a ref signal Clock Accuracy EE Ref Signal Not aref sigr aan aa Drigin Dest Desk O Local Address D ete 1056576 yf Time of day 0 Time of day os Reliability Flags 0 5 14 17 Reliability Flags 0 5 1114 17 set unreliable 643p 18 21 On unreliable 36 131 9 271 CAC Enable CAC Walid 9 10 11 12 12 14 15 16 17 l 19 20 21 22 23 Tramemita 05 00 00 00 oo oo so so
259. ency units used in ATS measurements are relative units expressing the relationship of the measured frequency to a reference frequency you have entered into the References gt Freq fields in the generator and analyzer panels F R This is a frequency ratio unit obtained by dividing the measured frequency F by the reference frequency R dHz delta hertz dHz is the difference in frequency between the mea sured frequency and the reference frequency dHz F R Hz percent hertz Hz is obtained by dividing the measured fre quency by the reference frequency and multiplying the result by 100 Hz 100 F fl R For example a measured frequency of 950 Hz would be expressed as 95 0 of a reference frequency of 1 kHz cent the cent unit is 1 100 of a musical half tone interval which in turn is the 12th root of 2 12 t Hz cen 100 7 octs octaves An octave is a frequency ratio of 2 1 For example with a reference frequency of 1 kHz a 2 kHz tone is expressed as 1 0 octave and a 500 Hz tone is expressed as 1 0 octave decs decades A decade is a frequency ratio of 10 1 For example with a reference frequency of 500 Hz a 5 kHz tone is expressed as 1 0 decade and a tone of 50 Hz is 1 0 decade ATS 2 User s Manual 379 Appendix A Units of Measurement Phase Unit 380 d delta percent d is 100 times the ratio of dHz or F R to the reference frequency R I R o 1 For example w
260. end of a ca ble or digital transmission system to estimate the worst case magnitude of jitter caused by reduced bandwidth of the transmission link Wfm Special Walking Ones and Walking Zeros Figure 97 Digital Generator Special Digital Generator El Walking Ones Ma Er Special a Walking Ones Samples Step 1 0000 Amalia zj Walking Ones is a signal in which only one bit is at logical one at any moment with the others all at logical zero The position of the bit which is at logical one is stepped continuously through the word from LSB to MSB to LSB and back to MSB again at a rate controlled by the Samples Step field Figure 98 Digital Generator Special Digital Generator lel Walking Zeros ad Fn Special a Walking eros Samples Step 1 0000 h En Amalia zj Walking Zeros is similar except that only one bit is at logical zero and all others are at logical one Walking Ones and Walking Zeros are typically used in troubleshoot ing circuitry where the digital word appears in parallel format in order to ATS 2 User s Manual 119 Chapter 9 The Digital Generator Dither 120 find stuck bits Dither is disabled for Walking Ones and Walking Zeros and the amplitude is fixed The walking waveforms can be observed on the DIO panel by viewing the bit indicators in the Data Bits mode rather than Active Bits mode Set the Samples Step v
261. enerator dBr Ref or the keyboard shortcut F3 You can set an Analog Generator dBr reference in V dBV or dBu units Frequency Reference The relative units of frequency for the Analog Generator are F R dHz Hz cent octs decs d and dPPM In a relative expression the frequency setting or reading is expressed in relation to a second reference frequency For Analog Generator relative fre quency settings this reference frequency is entered in hertz in the Analog Generator References Freq field or it can be entered on the fly from the current generator frequency setting with the menu command Edit gt Set Generator Freq Ref or with the keyboard shortcut Ctrl F3 Watts Reference Because the watt is a unit of power a voltage reading in Watts units will only have meaning if the circuit impedance is known To use watts levels select Watts as the Amplitude unit of measure ment and then set the Watts impedance reference to the correct imped ance value for your application The default value is 8 Q dBm Reference Because the dBm is a unit of power decibels relative to 1 mW a volt age reading in dBm units will only have meaning if the circuit impedance is known ATS 2 User s Manual Analog Generator References Chapter 8 The Analog Generator To use dBm levels select dBm as the Amplitude unit of measurement and then set the dBm impedance reference to the correct impedance value for your application The default
262. enever using the simple dB unit the expression must identify the reference value A large collection of units of measurement we ve seen it referred to as the dB zoo uses the decibel ratio with the reference stated as part of the definition of the unit Examples include dBV decibels in relation to 1 Vrms dBu decibels in relation to 7746 V rms dBFS decibels in relation to digital full scale dB spl decibels of sound pressure in re lation to 20 micropascals of pressure and so on The formula for decibels in voltage amplitudes is V dB 20log gt where V and V are the two related voltages The formula for decibels in power amplitudes is P dB 10log A 2 where P and P are the two related powers Analog Amplitude Units V volts unqualified This unit is used only on the Audio Analyzer and the Harmonic Distortion Analyzer panels Because of the detector differ ences between the Audio Analyzer Function meters and the other meters on these panels in some configurations V may have different meanings Specifically on all Audio Analyzer and the Harmonic Distortion Analyzer reading and reference fields except the Function meters V means volts rms Since the Function meters have switchable detectors the V units selection takes its qualification that is V rms or V quasi peak from the detector selection ATS 2 User s Manual Analog Amplitude Units Appendix A Units of Measurement Vrms volts
263. ep delay is also applied before batch mode DSP sweeps Ac quisition of signal into any of the Analyzer FFT batch mode programs will not begin until the pre sweep delay period or 200 ms whichever is greater has passed In nested sweeps using Source 2 the pre sweep delay is applied at the beginning of each nested sweep Pre Sweep Delay and Auto On The initial transient created when a generator is turned on requires a de lay before measurement to allow the generator DUT ranging and analyzer circuits to stabilize When Auto On is enabled the ON command is ap ATS 2 User s Manual 269 Chapter 15 Sweeps and Sweep Settling Table Sweeps 270 plied to the generator at the moment the sweep starts To avoid the effects of the switching transient set the Pre Sweep Delay to a sufficient time in many cases 5 sec to 1 sec or more See pages 79 and 101 for more information about Auto On Table Sweeps The sweeps we ve looked at so far step through a range of values set in Source 1 controlling ATS instrument settings as the independent vari able In a table sweep the points of measurement are read from a table rather than taken from Source 1 the Start Stop settings You must still use the Source 1 browser to choose the ATS instrument parameter that is to be used but the range direction number of steps and the step size are all de termined by the values entered in the sweep table This allows you to specify exact values
264. eprocess batch mode measurements after Optimizing Reprocessing is necessary when the X axis scale is changed Optimize only re scales the Y axis To return to your original display click Zoomout or Zoomout to Origi nal Copy to Sweep Panel It is often the case that after zooming or optimizing your graph you de cide that you should re run your sweep with Start Stop Top and Bottom settings which correspond to the coordinates on your resized graph A shortcut to this adjustment is provided with the Copy to Sweep Panel se lection Copy to Sweep Panel takes the modified graph calibrations pro vided by Zoom or Optimize and writes these as settings in the Sweep panel A new sweep will create a new graph with the X and Y axis calibra tions from the zoomed or optimized graph Display Cursors ATS provides two cursors as aids in interpreting your graph On the Graph Options menu click Display Cursors A green vertical line will ap pear with two display boxes at the top and the bottom of the graph adja cent to the cursor position The green line is actually two cursor lines on top of each other The value in the bottom display box on the graph is the X axis position of the cursors The value in the top display box is the difference between the X axis positions of the two cursors Since the cursors begin in the same po sition the initial difference is 0 00000 You can move the cursors by placing the mouse pointer on the green line an
265. eps rather than the value entered Zero Crossing The beginning and ending of any tone burst are always at the posi tive going zero crossing points of the sinewave which eliminates transients from the output Because of the zero crossing nature of the tone bursts only integer num bers of cycles can be entered as a Burst On or Interval setting if you are using s B units only time durations which represent multiples of the full pe riod of a cycle of the selected sinewave can be entered as a Burst On or Interval setting 86 ATS 2 User s Manual Choosing an Analog Generator Waveform Chapter 8 The Analog Generator Wfm Sine EQ if Analog Generator Wa Fri Sine en Cha F 41 00000 kH requency z rhe Figure 55 Analog Generator Sine EQ Auto On en ouTPuTs eee 618 Track 4 1 000 me Amplitude 1 000 me EQ Curve 105 5 rot rns Post EQ 105 5 mms Generator Equalization The Sine EQ setting outputs a normal sinewave with equalizing ampli tude changes made in the generator level according to an attached EQ data file This enables you to make a frequency sweep where the generator amplitude varies as instructed by the data in the attached file When you select Sine EQ and attach an EQ file see below a new field call Post EQ appears on the Analog Generator panel The Post EQ field displays the generator amplitude to be applied to the DUT which is value e
266. equire a stable ideal clock signal to use as a refer ence for comparison of the actual transition times Part of the Digital Interface Analyzer s acquisition and processing of the digital interface signal involves reconstruction of an ideal clock for use as the reference for jitter measurements The first three choices in the Jitter Detection field select the transitions at which the clock tim ing is compared to the interface signal X PRE Y PRE DATA AUX or AUDIO DATA 20 MSBs vucP AUX or AUDIO DATA 20 MSBs vucP LSBs LSBs PREAMBLE JITTER DETECTION STABLE BITS DETECTION ALL BITS Pn ee Dnt ee JITTER DETECTION Figure 165 Digital Interface Analyzer Jitter Detection Selections ATS 2 User s Manual 205 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer panel settings 206 Stable Bits The Stable Bits selection derives the stable reference clock at 1 4 the actual cell bit rate which is 8 times the audio sample rate Stable Bits is synchronized to the beginning transition of the preamble If Stable Bits is used the upper jitter detection frequency limit is reduced by 4 1 compared to All Bits This provides an analysis frequency range of approximately 380 kHz at a 48 kHz sample rate Stable Bits and Preambles will result in the lowest residual measure ment jitter Stable Bits will be sensitive to all sources of jitter in a typical system including jitter induced on an interconnect cable All Bits
267. er a Audio Precision im i n w gt tu i tn L 500 rn 500rn 500 rn 500 rm l p y i TE y Po nN hi 100n Figure 153 Digital Interface Analyzer eye pattern 48 kHz rate As indicated in Figure 151 this view requires these Sweep settings Source 1 Intervu Time m Data 1 Intervu Lower Eye Opening and m Data 3 Intervu Upper Eye Opening If you set Wave Display to Eye Pattern and then check Stereo Sweep on the Sweep panel these selections will be made Source 1 range should be O ns to about 165 ns and Data 1 and Data 3 ranges should be about 3 V These will vary according to your requirements signal conditions sample rate triggering choices and so on Jitter Waveform The jitter modulating the interface waveform can be recovered and viewed as a signal in its own right This selection shows the jitter waveform in the time domain ATS 2 User s Manual 193 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Waveform Views s 100p 200p Figure 154 Digital Interface Analyzer jitter waveform showing 10 kHz sinewave jitter from DIO jitter generator As indicated in Figure 151 this view requires these Sweep settings m Source 1 Intervu Time and m Data 1 Intervu Jitter sec or Intervu Jitter Ul Jitter is a time modulation and jitter amplitude is expressed in units of time either in seconds or in Ul You choose between the two expressions when you
268. er on any squarewave connected to the digital input connector for a range of 5 kHz to 15 MHz This feature permits measurement of jitter directly on the clock signal of ADCs and DACs The waveform of the jitter may be displayed in ATS 2 User s Manual Digital Interface Analyzer panel settings Chapter 12 The Digital Interface Analyzer the time domain view or a spectrum analysis of the jitter may be per formed using the frequency domain view Select Squarewave Rising to measure jitter on rising edges of the sig nal and Squarewave Falling to measure on falling edges Averages spectrum view only Figure 166 Digital Interface Analyzer panel Averages h Averages selections _ fi 3 The Digital Interface Analyzer enables you to average the results of multi ple acquisitions for frequency domain spectrum displays in order to re duce the variance of noise and to make coherent signals stand out more clearly The Averages field selects the number of acquisitions to be aver aged from 2 to 128 A selection of 1 disables averaging FFT Windows for the Digital Interface Analyzer Figure 167 Digital Interface Analyzer panel Windows Blackman Haris Window selections R Blackman Haris OUICE Hann Trigger Slope Flat T op Data Acquisitions E quiripple Hone The Digital Interface Analyzer has several FFT windowing functions available for its frequency domain views listed here m Blackman Harris The Blackman
269. eration Acquired Waveform Files As with other ATS tests you can save the setup and results of any Multitone Audio Analyzer tests as an ats2 test file The acquired waveform in the Multitone acquisition buffer however is not saved as part of a test If you want to keep the acquired data record for further analysis you must save it as an aam acquisition mono or aas acquisition stereo ac quired waveform file Single channel mono waveforms saved at different times can later be individually loaded into the two channels of the Multitone acquisition buffer to become stereo acquisitions for comparison in the time or fre quency domains ATS 2 User s Manual 233 Chapter 13 The Multitone Audio Analyzer Acquired Waveform Files 254 Saving Acquired Waveforms Figure 196 ATS Multitone Audio Save Stereo Waveform Analyzer Save Stereo Waveform dialog box To save an acquisition select the File gt Save As menu command choosing either the Stereo Waveforms aas or Mono Waveforms aam as the file type A stereo acquisition waveform file consists of two waveforms joined to gether into a single file a mono acquisition waveform file contains a single waveform To simultaneously save the waveforms from both acquisition buffer channels A and B select the stereo choice To save only one of the channels select mono The left half of the dialog box defines what will be saved into the first section of a wavefo
270. erator Choosing a Digital Generator Waveform sample rate which is approximately 24 kHz at a 48 kHz sample rate The frequency can be set in hertz or in a number of relative units see Fre quency Units page 372 Figure 75 Digital Generator Sine Waveform PIE O x Selections Shaped Burst EL Burst T Iriver sine U tfeet i O00 FFS Amplitude Wfm Sine Normal Figure 76 Digital Generator Sine Normal PASE CE a Frei Sine Normal Frequency 997001 kHz L Cha Ch B T Auto On W Track A T Invert E 1 000 FFS Amplitude The normal sine waveform is the standard waveform for most audio test ing and is the default generator waveform Wfm Sine Var Phase Figure 77 Digital Generator Sine Var Digital Generator Phase Er Sine var Phaze a Frequency 997001 kHz F ChA E on y Che Phase 6 4 0 00 0 00 deg This selection produces the selected frequency at both Channel A and B outputs but the phase of the Channel B output is variable from 180 to 179 99 with respect to the Channel A output as controlled by the Phase field A positive value entered in the Phase B A field will cause the Channel B output to lead the Channel A output A negative value entered in the 104 ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator Audio Precision Figure 78 Sine Var Phase triggered on Channel A the la
271. ermits quantization noise and distortion measurements of ADCs and digital systems You can also use a custom highpass filter file by selecting User HP See User Filters page 147 BW The Lowpass Filter Figure 120 The Audio Analyzer Det Auto B IEE BPYBR Fltr Freq BW Lowpass Filter Bw lt 10 He E 10H Fs 2 E E Sweep Toe 4 Freg 1 00000 kHz wis 1 000 y ufatts 8 000 Ohms dBm 00 0 Ohme The right BW bandwidth filter control field is the lowpass field The lowpass filter is effective in all Function meter functions except Crosstalk Bandpass SMPTE and Phase This field allows you to se lect essentially flat response at high frequencies the Fs 2 selection spe cific lowpass filters at 20 kHz 15 kHz or a User LP Fs refers to the currently selected sample rate as determined in the settings in the DIO panel for digital signals or in the Analog Input panel for analog signals Any lowpass filter when selected is connected in the measurement paths of both Function meter channels but does not affect the Level or Freq meters The 20 kHz and 15 kHz lowpass filters are six pole elliptic designs ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer Selection of a 15 kHz or 20 kHz lowpass filter when making THD N measurements is particularly important in measuring converters with large amounts of noise shaping Performance of the 15 kHz and 20 kHz lowpass filters is independent of sampl
272. es Sample rates that produce precise filter responses 32 000 kHz 65 536 kHz 131 072 kHz 44 100 kHz 88 200 kHz 176 400 kHz 48 000 kHz 96 000 kHz 262 144 kHz At any other sample rate the filter shape is preserved but the filter slides up or down in frequency by the ratio of the actual sample rate in use to the nearest sample rate from the list above User Filters User downloadable filters or user filters are custom designed software filters which can be designed for use in any of the three Audio Analyzer filter groups You can select a user downloadable filter for the Audio Analyzer in the same way that you choose one of the standard DSP filters The low pass and high pass filters are selected in the two fields to the right of the BW bandwidth designation The weighting filters are selected in the Fltr filter field DSP filters are not available in every measurement function of the Audio Analyzer Set the Function meter function to Amplitude 2 Channel Ratio or one of the two THD N modes to choose DSP filters Click the arrow to drop down the list of filters for any of these fields The last filter option on all lists selects the downloadable filter type appropriate for that setting User HP User LP or User Weighting Filter Although you can save many different user filter files for use in ATS you can only select one user file for each of the three filter positions at any one time When ATS is launched by defaul
273. es elections CHANNEL A CHANNEL A CHANNELA CHANNEL A CHANNELA CHANNEL A F Tunable CHANNEL A Highpass eta Detectors F Low Pass Weighting Notch p e Filters Filters Bandreject Ranging led RMS Fast RMS gt 0 0032 Lo pling Filter 8 Q Peak FUNCTION Highpass Low Pass Weightin Ta Detectors iia Filters k toning r gt Ranging gt RMS Fast RMS gt 0 0036 AC Coupling Filters Filters Bandreject amp Q Peak SEV Filter CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B Measurement Function THD N RATIO or AMPL Audio Analyzer Panel Figure 112 Conceptual Block Diagram THD N Functions THD N Ratio Function The THD N Ratio function expresses the sum of the distortion prod ucts and noise amplitudes relative to the amplitude of the unfiltered signal as measured by the Level meter in other words the result is a THD N to signal ratio Units of and dB decibels below the fundamen tal are ordinarily used with the THD N Ratio function THD N Ratio is the common way to express distortion However in an amplitude sweep THD N Ratio appears to show increasing distortion and noise with decreasing signal amplitude because the distortion and noise is stated as a ratio to the decreasing signal The THD N Ampl func tion may be more useful for amplitude sweeps ATS 2 User s Manual 135 Chapter 10 The Audio Analyzer The Function Meters 136 Results using the THD N Ratio function may be expressed in dB or X Y units
274. es modes if appropriate The Display Samples display mode is most likely to exhibit graphic aliasing If you use Display Samples be sure that the number of graph points is sufficient to correctly display the number of sample points in the time span Spectrum frequency domain Display Processing If the distance between the Steps in a sweep is greater than the width of one bin plotted points are selected by a mechanism called peak picking With peak picking the DSP searches all bins between the previous plotted point and the current point and plots the highest bin amplitude within that range This ensures that no peaks are missed Peak picking is used for all ATS FFEgenerated frequency domain displays ATS 2 User s Manual FFT StartTime Chapter 11 The Spectrum Analyzer FFT Start Time You can select any point in the acquired signal record as the beginning of the portion to be transformed This is the FFT Start Time The FFT is then computed for the contiguous section of samples starting at the sample at the start time and continuing for the number of samples chosen in the Lenath field This permits selective spectrum analyses of dif ferent sections of complex signals such as program material or special test signals such as sinewave bursts To change the value of FFT Start Time click in the field and type ina new number from the keyboard The maximum value for FFT Start Time depends on the sample rate the acquistion length in
275. es you to set a number of general behaviors for ATS These are m Prompt to Save Test when a test is closed Several commands such as File New Test File Open Test or File Open Data will close the current test clearing the test data from memory If this box is checked a dialog box will open when a test is about to be closed prompting you to save the test before closing it a Load LAST ATS2 on startup If this box is checked when ATS is launched the program will automatically load the test named Last ats2 m Save LAST ATS2 on exit If this box is checked when ATS is closed the program will automatically save the current test in memory as Last ats2 Keep all readings active during real time sweeps Normally ATS meters are constantly updating their readings If this box is checked all meters on all open panels will continue to update their readings during the progress of real time sweeps This enables you to view non swept parameters during a sweep If the box is not checked only the instrument readings selected as sweep parameters will update their readings which enables sweeps to run faster This setting does not apply to batch mode sweeps 362 ATS 2 User s Manual The Configuration panel Chapter 25 Configuration and the Utilities Menu m Display data in graph on test open If this box is checked data in a test is automatically graphed and compared to limits if any when the test is opened If the box is not checke
276. etup for the nine Digital In terface Analyzer views Digital Interface Analyzer Waveform Views The Digital Interface Analyzer offers two waveform views of the digital interface signal and one of the interface jitter signal Interface Waveform The interface waveform view shows the bi phase mark encoded bitstream which is the serial digital interface signal The 3 Ul wide pream ble cell is clearly visible in this view shown in Figure 152 See page 380 for an explanation of the unit interval or UI T 4 100n Fain 1 077p 1 4020 1 7284 2053p 2 3794 2 704p 3 355 Figure 152 Digital Interface Analyzer interface waveform display The Y preamble followed by six data cells is shown As indicated in Figure 151 this view requires these Sweep settings Source 1 Intervu Time and m Data 1 Intervu Amplitude ATS 2 User s Manual 191 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Waveform Views Source 1 range should be about 5 V Data 1 range will vary according to your requirements signal condi tions sample rate triggering choices and so on A range of 0 s to 4 us with a 48 kHz sample rate will show a preamble and a few data cells as in Figure 152 shorter spans will show pulse aberrations and rise and fall times a range of O sto 25 or 35 us displays an entire frame On the Digital Interface Analyzer panel Wave Display can be set to any choice except Eye Pattern Eve Pattern The eye
277. f responses m Pos Peak displays the greatest positive value during each measurement 66 ATS 2 User s Manual The DIO Input Section Chapter 7 The Digital I O Panel interval which is approximately 1 4 second for all peak monitor response modes m Neg Peak displays the greatest negative value during each measurement interval m Abs Peak displays the absolute value of the greatest positive going or negative going value during each measurement interval Abs Peak is always expressed as a positive number m 1 2 Pk Pk displays the value that is one half the peak to peak range measured during the measurement interval Data Bit Indicators 24 20 16 12 8 4 Figure 33 The DIO EN Active Bits Data Bit Indicators B Data Bits The Data Bit indicators show a bit by bit view of the embedded data in the digital signal audio word for each subframe The two subframes corre spond to Channel A and Channel B The bits are labeled from the left from the most significant bit MSB or bit 24 of the word to the least significant bit LSB or bit 1 of the word on the right The Data Bit indicators examine the signal in intervals of approxi mately 1 4 second The Data Bit indicators have two modes selectable by the option but tons to the right of the indicator rows When Data Bits is selected the indicators display green for a bit that is at data 1 at the moment of measurement and black for a bit that is at data O
278. f the amplitude versus frequency characteristics of vary ing signals ATS uses power law root mean square averaging to correctly average noise signals Averaging over many seconds or minutes of noise or of program mate rial such as music or voice is very useful in order to determine the long term average amplitude vs frequency distribution Coherent steady or continuous signals will be unaffected by spectrum averaging Variable signals such as noise and program material will con verge to their average values at each frequency as the averaging factor is increased The result is that the peak to peak variance in the displayed noise floor or program material is reduced while coherent signal ampli tudes are unchanged The average level of the noise floor is not changed 172 ATS 2 User s Manual Display Processing Chapter 11 The Spectrum Analyzer 100 120 140 160 1650 OL SS 10k 12 5k 15k 175k 20k Hz Figure 142 Low level signal viewed in the frequency domain 128x Power spectrum Only averaging Noise variance is reduced from noise variance shown in Figure 140 with no change in average noise level Figure 142 shows the same signal illustrated in Figure 140 after 128x spectrum averaging Note that the average level of the noise is about 160 dBV in either case but the peak to peak variance in the noise has been reduced by the spectrum averaging The slight rise in noise levels at high frequency due to noise shap
279. ferent time portions of the record perform FFTs of dif ferent transform lengths position the transform starting point at different places in the record change window functions change FFT post process ing modes change time domain processing modes etc The results of any and all of these different modes of analysis may be saved as ats2 test files Saving a test file however does not save the acquired waveform only the test setup and results It is possible to also save the acquired waveform which can be reloaded at a later time for further analysis See Saving Ac quired Waveforms on pace 183 Acquisition Length Set the lenath of the acquisition by selecting a value from the Acquire list The acquisition lengths are stated in samples the duration of the acqui sition will depend on the sample rate in use At a sample rate of 48 kHz a 256k acquisition will have a duration of 5 46 seconds Acquisitions can be equal to or longer than the FFT length you intend to use A longer acquisi tion enables you to perform transformations at different points along the length of the acquired record By choosing Track FFT you can set ATS 2 to acquire only the amount of data needed for the present transform length which is set in the FFT field to the left This provides faster performance compared to making lon ger than needed acquisitions See Transform Lenath below 160 ATS 2 User s Manual Transform Length Chapter 11 The Spectrum Analyzer
280. field in time seconds or by number of samples If the resulting lenath is less than the record length of the source the waveform is truncated at the end If the resulting length is longer then the source the source data is repeated until the specified waveform lenath is achieved Tips and Tricks When initially acquiring the audio signal in the FFT Spectrum analyzer panel set Window to None move to bin center The signal must be a sin gle sine wave 410 ATS 2 User s Manual Importing from WAV Appendix E AP Waveform File Support This selection shifts the frequency of the acquired signal to the nearest FFT bin center frequency effectively stretching or compressing the signal in time so that the number of waveform cycles in the analyzer transform buffer is an integer This is called a synchronous waveform and no win dowing function is necessary for useful FFT analysis After the acquisition is completed export the data in the Transform buffer using this Add In and selecting the Transform Instrument Source selection The resulting Windows PCM wav file is synchronous and can be imported into the Analog or Digital generators as an Arbitrary wave form Importing from WAV The Import wav File selection provides the capability to import audio data from a Microsoft Windows PCM wav file on disk into one of three 2700 Series instrument memory buffers the Arbitrary Waveform buffer the Acquisition buffer or
281. files is m ATS test file ats2 When you first launch ATS a default setup is loaded You can modify this initial setup by opening or closing panels changing configuration mak ing settings running a sweep and so on You can save your custom setup as a test under any name in any folder you choose ATS saves the instru ment and sweep setup information the input and output configuration the panel sizes and positions and so on If you have run the test and pro duced results the test data is also saved in the test file If you would like to return to a clean slate simply click the New Test button or the New gt Test command on the File menu ATS will discard your current settings and data and reload the default setup Macro Files Another important ATS file type is the macro file sometimes called a procedure file As in other programs a macro is a programming script which can automate program functions ATS macros are written in the pro gramming language AP Basic which is included with ATS The extension for macro files is m AP Basic macro file atsb ATS 2 User s Manual 25 Chapter 2 The ATS Control Software Working with Files and ATS 26 Data Files ATS stores all data from test results in memory as the test is run As men tioned before this information is saved along with panel and sweep setup information in a test file The data can also be viewed and edited in a panel called the Data Editor and can
282. for undithered PCM signals of any particular resolution The dither noise is introduced before quantizing and serves to random ize the quantization distortion and produce an undistorted signal with a slightly higher noise floor The elimination of quantization noise results in a more acceptable audio signal ATS 2 User s Manual Dither Chapter 9 The Digital Generator Dither Type Figure 99 Digital Generator Dither settings Dither Type Triangular Triangular Rectangular Shaped Volts FS Hone References The Dither Type list on the Digital Generator panel allows you to select three types of dither for the generator output signal or none The dither type names rectangular and triangular describe the shape of the graphs of the probability distribution function PDF of the noise signal cho sen for dither The effects of dither on a digital audio signal change with the level of dither applied and with the PDF of the dither noise signal The Output Resolution field on the DIO panel controls the amplitude of the dither added to the digital generator output Proper dither amplitude for a 16 bit system for example is obtained by entering 16 in the Output Resolution field The Dither Type list choices are m Triangular Triangular probability distribution function TPDF dither is the default setting in ATS and is recommended for most measurement applications It produces a slightly higher nois
283. fset is that a O dBFS signal displays a bits value of 0 29 A signal at 1 76 dB reads exactly zero bits ATS 2 User s Manual 377 Appendix A Units of Measurement Digital Data Units 378 Digital Data Units dec hex decimal and hexadecimal In addition to the digital domain units listed above which are values integrated over one or more signal cy cles the ATS Digital Generator also has decimal and hexadecimal units available These units express the numerical value of the embedded audio at each sample in either base 10 decimal or base 16 hexadecimal nota tion The decimal and hexadecimal values refer to the peak value when used with the AC waveforms of the Digital Generator The units dec and hex are used with the Special Constant Value digital dc waveform se lection and with the Offset parameter of the Sine Offset waveform Ratio Units percent The percent unit expresses the ratio of two numbers multi plied by 100 For example a ratio of 0 7 is expressed as 70 dB decibel The decibel is always a ratio of two amplitudes expressed logarithmically For voltage amplitudes decibels are computed by V dB 20log ta 2 See the sidebar on decibels page 372 PPM parts per million Parts per million expresses the ratio of two numbers multiplied by 1 000 000 For example a ratio of 0 00005 equals 50 PPM X Y The X Y unit is the simple ratio between two numbers Specific ratio units such as dBu
284. g Loss of the protective grounding connection can result in electrical shock hazard from the accessible conductive surfaces of this product For continued fire hazard protection fuses should be replaced ONLY with the exact value and type indicated on the rear panel of the instrument and discussed in the installation manual Getting Started with ATS 2 The AC voltage selector also must be set to the same voltage as the nominal power source voltage 100 120 230 or 240 V rms with the appropriate fuses Different fuses are required depending on the line voltage The International Electrotechnical Commission IEC 1010 1 requires that measuring circuit terminals used for voltage or current measurement be marked to indicate their Installation Category The Installation Category is defined by IEC 664 and is based on the amplitude of transient or im pulse voltage that can be expected from the AC power distribution net work This product is classified as INSTALLATION CATEGORY II abbreviated CAT II on the instrument front panel Do NOT substitute parts or make any modifications without the written approval of Audio Precision Doing so may create safety hazards This product is for indoor use pollution degree 2 ATS 2 User s Manual xix XX Lee Safety Symbols The following symbols may be marked on the panels or covers of equip ment or modules and are used in this manual WARNING This symbol alerts you to a potentially h
285. g Interface Waveforms 212 Audible Monitoring in the Digital Interface Analyzer 212 Chapter 13 The Multitone Audio Analyzer 213 Introduction 0000 bee ee ee eee 213 Overview Multitone Testing 214 Multitone Waveform requirements 215 Sample multitone waveforms 215 Creating custom multitone waveforms 216 Inside Information Multitone Generator Settings 216 The Multitone Audio Analyzer panel 217 Signal INPUtS aooaa a a a a a ee a eee 217 Peak Level MONItOFrS 218 Multitone MeasureMentS 218 Frequency Domain Views by default 218 Spectrum 0 2 00 ee ee eee 219 Response 00 000 bee eae 220 Distortion 0 000 eee ee 221 Noise 2 ee eee 222 Masking Curve 2 000 ee eee eee 224 Crosstalk 0 00 eee ee ee ee a 225 Time Domain View 8 288 226 ATS 2 User s Manual Frequency Resolution 0 226 Setting Multitone triggering resolution 226 Setting frequency resolution for rss summing 227 FFTLength 0 00 eee ee ee ee 227 Processing 00 cee ee ee ee ee 228 Triggering 6 acc podas das eS ee heh Eee risa 229 Off sea Beas ee eee eae eee ea eeeeeeeaeas 229 Digital Gen and Analog Gen
286. g fields on the Analog Generator and Digital Generator panels and on the DIO In put meter This calibration assumes a sinewave and is arithmetically scaled to the Vrms value by 2 V2 approximately 2 828 Since non sinu soidal waveforms are calibrated to have the same peak to peak value as a sinewave the Vpp unit should be correct for most non sinusoidal wave forms When used with the Analog Generator Vpp is an open circuit value and the actual output voltage will be less with a load W watts This unit of power is used on the Analog Generator and the Audio Analyzer panels Watts is calculated based on the P V R relation ship On the Analog Generator panel V is the setting in Vrms and R is the combination of the ATS 2 source resistance and the resistance of the exter nal load for an accurate setting you must enter the value of the load resis tance in the References Watts field on the generator panel On the Audio Analyzer panel V is the measured rms voltage and R is the value of ATS 2 User s Manual 373 Appendix A Units of Measurement Analog Amplitude Units 374 the source resistance which you must enter in the References Watts field on that panel dBm decibels relative to 1 mW Like Watts the dBm is a unit of power used on the Analog Generator and the Audio Analyzer panels dBm is calculated based on the P V R relationship On the Analog Generator panel V is the setting in Vrms and R is the combination of the
287. g signals measurement bandwidth may be increased to as high as approximately 120 kHz with the HiBW 262144 selection if the optional high bandwidth converter is installed in ATS 2 With digital signals bandwidth is intrinsically determined by the sample rate of the device or system being measured Audio Precision 50 60 70 80100 Figure 209 Fundamental top curve 2nd harmonic 3rd harmonic 4th harmonic and 5th harmonic amplitudes of a loudspeaker as a function of power The four Harmonic Sum meters are completely independent from one another On a given channel one may be set for even harmonics and the other for odd harmonics or one may measure a single individual har monic while the other measures an arbitrary group of harmonics that may or may not include the single harmonic selected on the other meter Each Harmonic Sum reading for each channel may be simultaneously plotted as a separate trace on the graph during a single sweep Amplitude Units If you click on the arrow to the right of any amplitude or Harmonic Sum meter reading field a list of measurement unit choices will drop down The units shown on the list depend upon whether Analog or Digi tal is selected in the Input field With Digital selected the units list displays m digital domain units FFS dBFS FS and Bits relative units dBr A and dBr B and units relative to the analog domain V dBu and dBV ATS 2 User s Manual Harmonic Distortion
288. g the Spectrum Analyzer the Sweep gt Start F9 com mand both acquires new data and performs the FFT Additional menu commands Sweep gt Transform data w o Acquire F6 and Sweep gt Reprocess Data Ctrl F6 provide you with other options These com mands are discussed in more detail on page 157 The acquired signal may be viewed in the frequency domain by select ing FFT Frequency for Source 1 and choosing the desired Start and Stop values on the Sweep panel Any portion of the acquired signal may be viewed in the time domain by selecting FFT Time for Source 1 and choosing the desired Start and Stop values on the Sweep panel You can easily set up a new FFT and then toggle between time domain and frequency domain views using the Sweep Spectrum Waveform Button which is discussed on page 182 Both channels of the acquired waveform remain in the DSP acquisition buffer until one of the following events occurs ATS 2 User s Manual 159 Chapter 11 The Spectrum Analyzer The Acquisition Record m a Sweep gt Start or Go or F9 command is issued to acquire new waveforms m a different Analyzer instrument is loaded m power is turned off to ATS 2 or m a different acquisition waveform is loaded from disk as described in Loading Acquired Waveforms on page 185 While the waveform is still present in the acquisition buffer full flexibility exists to change back and forth between time and frequency domain analy sis You may view dif
289. generated at the beginning of each Channel A subframe each X preamble plus each Z preamble in the interface signal transmitted at the digital output If jitter has been added to the digital output that jitter will be reflected in the trigger waveform a ChB Xmit Subframe A trigger transition is generated at the beginning of each Channel B subframe each Y preamble in the interface signal transmitted at the digital output If jitter has been added to the digital output that jitter will be reflected in the trigger waveform a ChA Xmit Subframe DedJitt A trigger transition is generated at the beginning of each Channel A subframe each X preamble plus each Z preamble in the interface signal transmitted at the digital output before the addition of any jitter ChB Xmit Subframe DeJitt A trigger transition is generated at the beginning of each Channel B ATS 2 User s Manual 347 Chapter 22 Sync Ref Trigger and Aux 348 z Auxiliary Control Output and Input subframe each Y preamble in the interface signal transmitted at the digital output before the addition of any jitter Xmit Block 192 frames A trigger transition is generated at the beginning of each Status Block frame each Z preamble in the interface signal transmitted at the digital output This occurs once every 192 frames ChA Sync Ref Rcv Sub Frame A trigger transition is generated at the beginning of each Channel A subframe each X preamble plus each Z prea
290. get Range display bar to a readings Bar Graph Target Range displays a dark bar over the magenta bar to give a visual indi cation of a range of interest Refer to the previous Bar Graph Setup topic for information on setting a Target Range Using a Bar Graph for Settings To use a Bar Graph for settings you must create the graph while an in strument setting field is highlighted or you must select an instrument set ting parameter from the Connection browser in the Bar Graph Setup panel if Bar Graph 1 Digital Generator Ch Amplitude Min 420 0 mms Mas 760 0 mirma A O gna Wace esse ecg lua eles fa A aie to atv teghanto ava 00m 400m BOOM oUO mn 1 Vrms Figure 239 Typical Bar Graph for settings Bar Graph settings are displayed as green digits and also as a horizontal white bar with a slider control Moving the slider along the bar will adjust the signal setting in real time simulating an analog control You can re move the slider bar display by selecting Display Digits Only on the Setup panel You can move the slider by dragging it with the mouse pointer or if the slider has been most recently selected by using the left and right keyboard arrows The minimum setting step can be changed by entering a new value into the Increment field on the Bar Graph Setup panel When the slider has been moved a blue horizontal bar will appear on the white bar to indicate the history of minimum and maximum setting
291. h Acw Sub Frame I Codi ChB Rev Sub Frame Ch Acv Sub Frame Devitt References ChE Rev Sub Frame Devitt Row Block 192 frames Row Error Freq 1 00000 kKHa ChA wmit Sub Frame ChE lt mit Sub Frame Ch mit Sub Frame Delikt ChB mit Sub Frame Deitt mit Block 192 frames Ch Sunc Ref Row Sub Frame Che Sync Ref Row Sub Frame SyncAef Aey Block 192 frames Sync Ret Rew Error The Digital Interface Analyzer has an extensive trigger source list with the additional capability of triggering on up to four error conditions from ei ther the digital input or the SYNC REF input These selections are identical to the choices on the Main Trigger panel both panels control the same functions interactively See Main Trigger panel on page 345 in Chapter 22 for a detailed description of every trigger source When Go is pushed the timing of the beginning of the Digital Interface Analyzer acquisition is determined by the Trigger Source and Receive Error selections the Trigger Slope buttons and the Data Acquisition buttons The various Trigger Source choices include several points in the digital interface from the received digital input the transmitted digital out put or the Sync Ref received input from an external clock reference the AC mains frequency and internal generators The trigger from the digital in terface signals can be extracted from the X and Z preambles Channel A subframe the Y preambles Channel B subframe or the block
292. he OSR The output sample rate set here the OSR is available on the Analog In put panel as a sample rate choice for the input ADCs OSR also shows up on the Analog Generator panel as a sample rate selection for the DACs used in arbitrary waveform conversion and as the Pass Thru sample rate OSR is also available as an embedded frequency scaling factor selection in the Scale Freq by field in both the Output and Input sections of the DIO panel where it is called Output Rate When using the Dual Connector modes ADCs or DACs using OSR as a sample rate selection are clocked by the connector rate the cable rate Frequency scaling is always by the overall rate The output rate may be swept as part of a test by selecting Dio as the in strument and Output Sample Rate at Source 1 or Source 2 on the Sweep panel See Chapter 15 for more information about sweeps Voltage See Figure 17 for reference The Voltage field displays the output amplitude of the serial digital inter face signal Serial digital interface signal voltage is measured in volts peak to peak Vpp The signal voltage maximum for the XLR connector setting is 5 10 Vpp typical of the AES3 professional standard voltage maximum for the BNC connector setting is 1 275 Vpp typical of the AES3id professional standard and twice the voltage of the IEC60958 3 consumer standard The voltage of the interface signal can be varied to simulate cable atten uation and test the perfor
293. he Status Bytes panel as usual You can choose whether or not to dither the re sam pled REF IN signal The amplitude relationship between the REF IN signal and the Dicital Generator output is controlled by the Digital Generator output amplitude setting A setting of 1 00 FS 0 dB FS will pass the REF IN signal unattenuated and lower settings of generator amplitude will attenuate the audio level Wfm Special Monotonicity Figure 95 Digital Generator Special Digital Generator Monotonicity wifi Special Y Monotonicity Samples Step 1 0000 zj lt Amplitude zj Monotonicity is a low amplitude staircase waveform It consists of five complete cycles of squarewave at each of the ten lowest non zero digital ATS 2 User s Manual 117 Chapter 9 The Digital Generator Choosing a Digital Generator Waveform 118 amplitude states plus the same time period at zero Since this definition is with reference to the minimum possible amplitude the absolute amplitude of the steps depends on the Output Resolution value word width in bits on the DIO panel The squarewave half cycle duration is controlled by the Samples Step field For example with a Samples Step value of 10 at a 48 kHz sample rate the squarewave half period is 10 48 000 seconds or 208 3 us each equal amplitude section is ten half periods long or 2 083 ms and each eleven step repetition occurs at a rate of 11 x 2 083 ms or every 22 92
294. he amplitude or phase if selected of every bin without discrimination it is useful for verification of signal presence but not for analysis Y e a AR 200 Suu Hz Figure 180 Typical Multitone Spectrum measurement Spectrum normally displays amplitude vs frequency but will show phase vs frequency if Fasttest Phase is selected as a Sweep Data instru ment ATS 2 User s Manual 219 Chapter 13 The Multitone Audio Analyzer Multitone Measurements Response mode displays a response curve drawn through the ampli tude or phase if selected measured in each of the bins that correspond to a stimulus tone in the multitone signal This gives the gives the frequency response or phase response of the DUT Figure 181 Example of a ANNETTA multitone frequency response graph Fi F2 F3 F4 F5 F6 F7 F8 In the multitone frequency response example diagramed in Figure 181 the amplitude in each of the bins which are known to have tones is shown as a light gray line The dark line represents the frequency response curve Figure 182 Example of a deg Suen yarn ae multitone phase response graph deg Fi F2 F3 F4 F5 F6 F7 F8 Response normally displays amplitude vs frequency but will show phase vs frequency if Fasttest Phase is selected as a Sweep Data instru ment In the multitone phase response example diagramed in Figure 182 the phase in each of the bins which are known to have tones is shown as a light gray l
295. he difference may become large For example when the distortion products are at 10 0 the differ ence in amplitude between the fundamental component and the com plex signal including distortion is less than 0 5 so distortion values stated as a percentage of either value are nearly the same At 45 typi cal of a squarewave there is about a 9 6 difference between stating distortion ratios relative to the fundamental rather than to the entire distorted input signal The ATS 2 Harmonic Distortion Analyzer makes a selective ampli tude measurement of the fundamental signal and refers all Ratio units to that value conforming to definitions The ATS 2 Audio Analyzer in the THD N Ratio function like all other commercially available THD N analyzers refers the distortion product measurements to the raw input signal that includes fundamental and harmonics ATS 2 User s Manual 255 Chapter 14 The Harmonic Distortion Analyzer Sweeping and Graphing Results Sweeping and Graphing Results The fundamental and the harmonic products measured by the Har monic Distortion Analyzer can be swept and graphed in ATS The Harmonic Distortion Analyzer must be selected as the Analyzer instrument Choose Harmonic as the instrument in the Sweep Data or Source browser and the following Parameter selections will be available for sweeps ChA Fund Ampl a ChA Fund Freq a ChA Harm Sumi a ChA Harm Sum2 ChB Fund Ampl ChB Fund Freq ChB Harm Sum
296. he digital audio interface transmitter module and to the balanced unbalanced and optical digital outputs The output of the second DSP signal generator the ATS 2 User s Manual Other Documentation for ATS 2 Chapter 1 Introduction Analog Generator is converted to an analog signal by a digital to analog converter DAC The two channel output of the DAC is conditioned and ranged for the balanced and unbalanced analog outputs All signal analysis is also performed in the digital domain in DSP The digital input is routed through a digital audio interface receiver and applied to the Analyzer DSP Analog inputs are first ranged and conditioned for do main conversion and then are sampled by a high resolution or option ally a high bandwidth analog to digital converter ADC before being applied to the Analyzer Analog Domain Digital Domain Discussions of audio technology often place the signals into one or another of two realms the analog domain or the digital domain These terms provide a useful conceptual division Analog audio signals are analogies of the sound waves that they represent varying in frequency and amplitude in a continuous fashion In audio electronics these are voltages and currents that are manipu lated by modifving their amplitude or frequency The term analog do main refers to signals represented and processed in this fashion Digital audio signals on the other hand are numerical representa tion
297. he opposite channel see BP BR Filter Tuning on page 149 The BW high pass and low pass and Fltr weighting filter selections are not available for the Crosstalk function THD N Functions The two THD N total harmonic distortion plus noise functions use bandreject notch filters to remove the fundamental sinewave signal so that the detector can measure the remaining harmonic distortion products and noise ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer The bandreject filter center frequencies may be fixed or may track one of several parameters See BP BR Filter Tuning on page 149 Figure 112 shows a conceptual block diagram of the Audio Analyzer with the THD N functions selected A A CHANNEL A PEAK m z 1 442 Vp METERS n EEEE 1 wg CHANNEL B a a a p CHANNEL A CHANNELA CHANNEL A CHANNEL A B Digital a Analog Analog AES A to D Peak Receiver 7 Converters Detectors Ranging AC DC Input Coupling _1__ lt l l 3 m CHANNEL B CHANNEL B CHANNEL B CHANNEL B a Inputs Analog Input Panel DIO Frequency References CHANNEL A Digital CHANNEL A AC DC FREQUENCY Coupling SSS METERS CHANNEL B CHANNELA CHANNEL A Detectors CHANNEL A Ranging RMS 1 005 V J LEVEL amp Fast RMS INE METERS CHANNEL B CHANNEL B della Detector Amplitude s mg Settings Referenc
298. her concepts used in FFT analysis see Appendix C 200 500 ZJO JUL Hz Figure 173 Spectrum View of Typical Multitone Stimulus Signal Although it can be output by either the Analog or the Digital Genera tors a multitone waveform is generated in DSP and is designed so that all the sinewaves will be synchronous The multitone signal is applied to the DUT and an acquisition of the de vice s output is made for analysis Since the waveform is synchronous each sinewave falls only into its own bin maximizing frequency resolution Any harmonic distortion products created in the DUT will also be synchro nous and each of these products will fall into its own bin as well The FFT data can then be interpreted in several ways extracting ampli tude phase distortion noise and crosstalk results Multitone can provide detailed accurate and very fast measurements using a short multitone burst The Multitone Analyzer normally provides a frequency domain spec trum analyzer view of the signal A time domain oscilloscope view is also available but is rarely used 214 ATS 2 User s Manual Overview Multitone Testing Chapter 13 The Multitone Audio Analyzer Multitone Waveform requirements A multitone test signal is a complex waveform the combination of two or more sinewaves There are typically from 3 to 30 or more tones ina multitone signal to the ear it sounds like a dissonant organ chord Figure 174 Example of mul
299. hich express the relationship of a value to a user supplied reference or to another ATS setting Figure 284 Selecting Units of MM a 1008 Y Measurement for ATS 1000 FFS readings and settings 100 000 FS 0 000 dEFS 0 29 Bits 1 000 rm 1414 Vp 2020 Ypp 2218 dBu 0 000 dE 8 239 dEr 0 239 dBrlrv O3B08b0b dec fFFFFE hex Depending on the current ATS configuration and the parameter you are setting or observing different units choices will be available Any reading display or setting field which has a drop down arrow offers a list of units of ATS 2 User s Manual 371 Appendix A Units of Measurement Analog Amplitude Units 372 measurement Click the arrow to display the list and choose the units you prefer Setting fields also allow direct entry in the field to select units When you request a value in different units ATS does the calculation for you The decibel The decibel or dB in one form or another is arguably the most widely used unit of measurement in the field of audio The ear s re sponse to both sound amplitude and frequency is usually best exam ined in logarithmic terms and the dB being a logarithmic unit of measurement is often the right choice It is important to remember that the dB is always a ratio of two val ues and for a meaningful expression both of the values must be known While 8 dB means nothing 8 dB below the input signal gives us a reference and is meaningful Wh
300. hich you can apply to your data as selections on the Compute menu as shown in Figure 246 Figure 246 Compute menu commands ATS 2 User s Manual 317 Chapter 19 Performing Computations on Data The Compute Dialog Boxes Additionally the menu provides a Compute Status command which opens a dialog box to view and edit the list created by applying the Apply After Sweep option to one or more Compute algorithms At the bottom of the menu is the Clear All and Reset command These commands are discussed on page 326 The Compute Dialog Boxes Although each of the 10 Compute dialog boxes has different features as sociated with a particular compute algorithm all the boxes are similar and have the following checkboxes and buttons in common Figure 247 Compute dialog box common features Data to Compute p Apply After Sweep Data Data 2 MT Data 2 Data 4 Data 5 _ Data 6 Compute Cancel Close Compute And close Each Compute dialog box has a list of six checkboxes labeled Data 1 through Data 6 The Compute algorithms will only operate on the data trace or traces you have selected leaving the other data untouched You can select different combinations of data traces in different Com pute algorithm dialog boxes Four buttons give you the following commands a Cancel Abort the operation m Close Keep the settings made and close the dialog box Compute Perform the computation while leaving the dialog b
301. hs Trace Colors 302 ATS 2 User s Manual Bar Graphs Each ATS instrument has a number of settings and readings on its con trol panel the Analog Generator for example has fields to set frequency and amplitude and the Audio Analyzer has fields to read these parame ters e Bar Graph 1 Analyzer Level Tol x Min 72 299 dBFS Max 17 995 dBFS dBFS Nominal Level should be 12 dBFS 4 P ee Figure 235 Typical Bar Graph reading with optional comment Bar Graphs are graphical display panels that can be associated with in strument settings and readings for easier control and observation Up to 32 Bar Graphs can exist simultaneously associated with any combination of instrument parameters Bar Graphs can be set to any size Bar Graphs are not related to the graphs controlled by the Sweep panel and displayed on the Graph panel Creating a Bar Graph A Bar Graph can be associated with any ATS field that sets or reads a signal parameter ATS 2 User s Manual 303 Chapter 17 Bar Graphs Bar Graph Setup To create a Bar Graph click on the setting or reading field to be associ ated with the Bar Graph then either click on the Bar Graph icon or choose Panels gt Bar Graphs gt lt new gt A new Bar Graph will be cre ated and associated with the parameter that you highlighted If no appro priate field was highlighted the default new Bar Graph association is with the Audio Analyzer Level Meter Channe
302. ht you can set the number of times to repeat the phase randomization before selection of the best candidate Since the phases of the tones are randomly changed during this process the resulting multitone waveform will provide meaningful results only in interchannel Ch B Ch A phase measurements m Create Stereo Waveform By default the Multitone Creation Utility generates a mono Audio Precision generator waveform file with the filename extension agm If this box is checked a stereo waveform file is generated with the filename extension ags When Create Stereo Waveform is checked two option buttons appear below the checkbox e Stereo Waveform Amplitude Make both equal The A and B channels of a waveform unless identical will have different crest factors This choice optimizes the level of the channel with the higher peak amplitude at the selected Headroom setting then modifies the amplitude of the opposite channel by the same factor ATS 2 User s Manual 237 Chapter 13 The Multitone Audio Analyzer Creating Multitone Waveform Files 238 e Stereo Waveform Amplitude Optimize individually for Headroom This choice optimizes the peak level of each channel individually with respect to the Headroom setting Since the channels will likely have different crest factors the level of the fundamental tones in the two channels will likely be different after optimization At the bottom of the panel there are four buttons a Use exi
303. hts when the digital input phase locked loop is un able to lock to the incoming signal The Coding Indicator The Coding indicator shows a deviation from proper bi phase coding in the input serial bitstream Since the subframe preambles deliberately de viate from the bi phase coding rules in order to provide a unique synchro nization signal preambles are excluded from the function of the Coding indicators The Parity Bit Indicator The Parity bit indicator indicates a parity error within a subframe Cor rect parity is determined by comparing the parity bit bit 31 the P bit with the sum of the remaining 31 bits in each subframe Any one bit error or odd number of bit errors introduced in transmission will cause a Parity error indication A deliberate parity bit error the P bit set high can be transmitted from the ATS 2 digital output by checking Parity in the DIO Output Send Errors section Unfortunately even numbers of bit errors within a subframe cannot be detected by the parity technique ATS 2 User s Manual The DIO Input Section Chapter 7 The Digital I O Panel The Validity Bit Indicators Two additional indicators show whether the Channel A and B validity bits bit 28 the V bit are asserted or not A validity bit is associated with each subframe Exactly how or if the validity bit is set depends upon the design of the particular digital device being measured For example a DAT machine may set i
304. i ChB Harm Sum2 254 ATS 2 User s Manual Sweeps and Sweep Settling Introduction Sweeps and Graphs A sweep is a measurement which includes a number of points of data the result of varying or sweeping one or more test parameters across a certain range and reporting the value of other test parameters at regular points during the sweep You can force ATS to perform a single point sweep for special purposes but generally the term sweep indicates that a number of data points are included in the measurement Audio Precision EQ FREQUENCY RESPONSE RIAA Phono Preamp 2UU a Figure 212 Graphical display of sweep results The results of a sweep can be listed in a table and viewed in the Data Editor more commonly the results are plotted on a Graph As you will ATS 2 User s Manual 255 Chapter 15 Sweeps and Sweep Settling Introduction Sweeps and Graphs see ATS s Sweep Data Editor and Graph functions are closely tied When the Data Editor and the Graph panel are open next to your Sweep panel you can watch the data values and the graph coordinates and traces re spond to your Sweep panel settings See Sweep Display Mode page 265 Graphs page 285 and Editing Data and Setting Limits page 307 Many times aspects of sweep functions can be described in graphic terms for example the Source divisions are called X axis divisions Data results are often called traces and so on The A
305. i 750 Hz Detectors CHANNELA Sideband AC High Pass H demodulator Low Pass Coupling Ranging RMS des PMS PRES Filter Filter 8 Q P FUNCTION 2kH 750 H Detect METERS z z etectors High Pass Paci Low Pass Beare Ranging RMS Fast RMS gt 0 00110 Filter Poor Filter kang amp Q Peak CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B CHANNEL B Measurement Function SMPTE DIN Audio Analyzer Panel Figure 114 Conceptual Block Diagram SMPTE DIN Function Phase Function Figure 115 shows a conceptual block diagram of the Audio Analyzer with the Phase function selected The Phase function measures the phase difference between the signals which must be the same frequency on the two input channels The phase difference always expressed in degree units is shown in the left hand Function meter display The value displayed is phase B A the same expression used for the Sine Var Phase waveforms of the Digital and Analog Generators If Channel B leads Channel A the display will show a positive reading if Channel B lags Channel A the display will show a negative reading 138 ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer CHANNEL A PEAK 1 442 Vp METERS e we nE 12 1 1 wg CHANNEL B gt Digital Receiver Input ss n CHANNEL A CHANNEL A CHANNEL A CHANNEL A A o Analog Peak Ranging AC DC Detectors Coupling a d Inputs CHANNEL B CHANNEL B CHANNEL
306. ications The most common applications of generator equalization are to produce a nominally flat output from a device which contains a known equalization function Typical examples would be U S FM and TV aural broadcast transmitters using 50 us and 75 us preemphasis curves By attaching an equalization curve to the ATS 2 generator that is the in verse of the nominal curve used in the device under test the resulting mea sured output should be flat Small variations from flatness will be a measurement of the accuracy of equalization in the device since the atsq curves provided are accurate to better than 0 01 dB and the specified gen erator flatness is of the same order Wfm Sine Burst Figure 85 Digital Generator Sine Burst Digital Generator ajaj Er Sine a Burst Frequency 997001 kHz ChA ChB Burst onfi Cycles Interval 3 Cycles h Low Level 250 0 mY ra Auto On T Frack amp M Invert E 1 000 FFS Amplitude 1 000 FFS The frequency of the sinewave is set in the Frequency field The Ampli tude field sets the generator amplitude at the maximum burst ON level ATS 2 User s Manual 109 Chapter 9 The Digital Generator Choosing a Digital Generator Waveform 110 Figure 86 Tone Burst Definitions GENERATOR AMPLITUDE WV LOW LEVEL l l BURST ON gt p4 INTERVAL gt Refer to Figure 54 for definitions of the following settings Burst Enter a value
307. ich are located in the center of Audio Ana lyzer are separate instruments which can measure the input signal in a number of different ways by applying different measurement functions The Function meters also add the option of using signal filtering as well as an additional detector selection The Function meters are the real power of the Audio Analyzer Most of the measurements you will make with the Audio Analyzer will be us ing the Function meters with the Level meters as convenient secondary signal monitors Function Meter Measurement Functions The Function meter measurement function selections are Amplitude m 2 Ch Ratio ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer m Crosstalk m THD N Ratio s THD N Ampl m Bandpass a SMPTE DIN m Phase Each function is discussed in detail below Amplitude Function Figure 109 shows a conceptual block diagram of the Audio Analyzer with the Amplitude function selected A A CHANNEL A PEAK 1 442 Vp METERS e wp we eee x CHANNEL B n j CHANNEL A CHANNEL A CHANNELA CHANNELA m Digital Analog Analog AES A to D Peak Receiver a Converters Detectors Ranging AC DC Input Coupling d A 4 n CHANNEL B CHANNEL B CHANNEL B CHANNEL B Inputs a DIO Analog Input Panel i AS a a a a LJ a a a s llo y
308. ide Trace The stored reference trace appears in the color gray on the screen and can be switched on and off with this command You may also use the keyboard shortcut F8 as a toggle m Delete Trace Click Delete Trace to clear the Graph Buffer memory You may also use the keyboard combination CTRL F8 This feature allows you to use a measurement of a specific unit or condi tion as a visual reference for comparison or adjustment of other units Reference traces are retained and properly plotted even if you change graph scaling and calibration including the use of zooming and optimiza tion Units of measurement can be changed as long as the unit domain re mains the same volts to watts to dBu for example Reference traces are NOT retained through changes between analog and digital domain or when plots are changed from absolute units to ratio units Reference traces are displayed in the color gray Graph Legend A A O O E CA DSP Anir THD N Left an 00 a Ampl 44 942 dB 44 847 dB 0 57263 0 57237 10 00 p 14 68 uFFS DGen Ampl 48 175 dB 48 281 dB 1468 uFFS DGen Ampl 0 38570 0 38094 21 54 uFFS DGen Ampl 51 509 dB 51 615 dB 215 4 UFFS DGen Ambl 0 02658 0 02595 Figure 231 The Graph Legend 294 ATS 2 User s Manual Graph Legend Chapter 16 Graphs On the Graph panel immediately beneath the graph itself is a display called the Graph Legend The Legend displays one row for each graph trace
309. ield ATS 2 User s Manual Digital Interface Analyzer panel settings Chapter 12 The Digital Interface Analyzer Data Acquisition The Digital Interface Analyzer data acquisition length is fixed at 1 572 864 samples which at the 80 MHz sample rate of the Digital Inter face Analyzer ADC gives an acquisition duration of 19 66 ms The Data Acquisition buttons select whether the acquisition is the 19 66 ms before the trigger event or the 19 66 ms after the trigger event See Figure 169 Receive Error Triggers Figure 170 Digital Interface Analyzer panel Source aaa NE Receive Error Trigger selections Tage be RE C Neg Data Acquisition f Post tig Pre trig Recelve Error Triggers M Confidence W Lock M Coding e Parity The receive error selections cause data to be acquired when the AES3 receiver of the DIO module detects one or more parity coding lock or confidence errors The checkboxes permit the selection of any or all these types of error to cause triggering Sync Error is identical to Receive Error but pertains to a signal con nected to the rear panel SYNC REF IN connector rather than the front panel input connector Depending upon whether Pre Trigger or Post Trigger Data Acquisi tion was selected the data in the buffer will precede or follow the first er ror detection References References Freq OO000 kHz Figure 171 Digital Interface Analyzer panel References The Freq value serves as the
310. ient to describe the re lationships of the sinewaves which make up the waveform and with fur ther computation the FFT results can be interpreted for several different types of display In ATS the amplitude spectrum results and the phase spectrum results are stored in a memory area called the Transform Buffer These results are read and recomputed for the various display options Much of the signal analysis in ATS 2 is performed using FFT techniques The Spectrum Analyzer the Digital Interface Analyzer the Multitone Ana lyzer and the Harmonic Distortion Analyzer all depend on FFTs The re sults are usually displayed as frequency domain spectrum analysis graphs but with recalculation the same data can be interpreted and displayed in other ways Also the acquisition can be displayed in the time domain as oscilloscope or waveform views Real Time vs Batch Mode In ATS 2 an FFT does not work in real time with continually updating displays Instead a sample of the signal is acquired then transformed mathematically the FFT then processed for display and shown on the ATS 2 User s Manual 393 Appendix C FFTs 394 Acquiring Data screen In Audio Precision instruments this is called batch mode since the data is acquired and processed in discrete batches The Spectrum Analyzer instrument is the most straightforward and flexi ble of the FFT based tools in ATS 2 and we will use it as the example
311. igital DUT as a stimulus signal As mentioned above the digital interface signal is configured under the control of the DIO panel The Digital Generator and the Analog Generator discussed above are similar in appearance and function The Analyzer After input conditioning audio from the analog or the digital inputs can be routed to the ATS 2 Analyzer Because the Analyzer uses DSP tech niques for measurement and analysis the audio must be in the digital do main The audio from the digital input can be applied directly to the ATS 2 User s Manual The Analyzer Chapter 5 Signal Analysis with ATS 2 Analyzer without need of conversion the analog inputs as we have seen are converted to the digital domain by high performance ADCs Click Panels gt Analyzer or the Analyzer button on the Panels toolbar to open the Analyzer panel Real Time and Batch Mode Measurements Many of the ATS meters and instruments display their results in real time that is their displays update so quickly that moment to moment vari ations can be observed on a continuous basis There is some variation in just how quick real time measurements actually are most of the ATS me ters have variable detector rates and the DIO interface monitors update at approximately 4 times per second Within certain ranges however real time measurements provide immediate results Other ATS instruments must first acquire a sample of the signal to be an alyzed and then
312. ignal to the Analog Outputs and the Digital Generator which is the source of the audio embedded in the Digital Out put signal The Analog and Digital generators both produce their signals in DSP and they are similar in operation and in the settings available on their re spective instrument panels The two generators are completely independ ent and can generate different waveforms simultaneously See Chapter 9 for more information on the Digital Generator Signals for Analog Measurements The Analog Generator creates audio signals in DSP that are converted to the analog domain with two high precision digital to analog converters DACs The resulting analog signals are then buffered and conditioned ATS 2 User s Manual 77 Chapter 8 The Analog Generator 78 The Analog Generator Panel and routed to the analog output circuitry The outputs are configured by settings on the Analog Generator panel The Analog Generator Panel Open the Analog Generator panel by choosing Panels gt Analog Gen erator by clicking the Analog Generator button on the Panel toolbar or by the keyboard shortcut Ctrl G Like most ATS panels the Analog Gen erator can be viewed in two sizes Double click the panel Title Bar to change sizes Figure 41 The Analog Generator Panel e Analog Generator Ox wfm Sine Normal Frequency 1 0000 kHz x C Cha ChB 1 000 Wins Amplitude gt EL Curve zj eaea Configurat
313. ignals typically used in ADCs and DACs The Jitter Detection interface signal selections are Stable Bits All Bits Preambles ATS 2 User s Manual Digital Interface Analyzer panel settings Chapter 12 The Digital Interface Analyzer The Jitter Detection squarewave selections are Squarewave Rising m Squarewave Falling These modes are described in the following sections AES3 IEC60958 Jitter Detection The AES3 IEC60958 digital interface encodes two channels of digi tal audio into a single serial data stream The serial signal consists of 32 cells bits per subframe and two subframes left and right channels per frame for a total of 64 data cells per frame The frame rate is equal to the sample rate of the embedded audio There are 64 cells bits in a complete frame and the cell rate is 1 64 the audio sample rate The first four cells of each subframe are the preamble The preamble always starts with a 3 UI 1 5 cell wide pulse followed by sequences of 1 UI 2 UI and 3 UI pulses which are differ ent among the three possible preambles See Appendix B for more in formation on the serial digital interface signal An ideal pulse train would have regular transitions at exactly equal intervals corresponding to a master clock frequency Jitter is the differ ence in timing of actual transitions of the pulse train from the instants when the transitions should theoretically have occurred Therefore jit ter measurements r
314. iguring on ss be wear 94 diagram amp description 36 front panel connectors 32 Analog to digital converter foranaloginouts 41 for Digital Interface Analyzer 188 Analysis overview see signal analysis overview 41 AP Basic documentation 353 Extensions Manual 7 OVerV eW 351 User s Guide Manual APIB 31 APIB interface rear panel connector 34 Append data saved infiletosweep 266 sweep setting 266 APWIN to ATS translator 417 Arbitrary waveform shared memory buffers 92 115 Arbitrary waveforms 91 114 ASCII datafile 315 ASTIE ose bee e er beaececteh ited 315 431 Index ATS 2 Measurement Software overview 248 9 panelreadings 12 panelsettings 11 panels overview 10 Status bar ok buen ae eo oe ee Ed 19 User interface 9 atsSafille o 310 atsb file 351 ASIF gt aro onarrrena roo 310 atsq file wu hee Re ee SER 310 SST ow wank De he we ew we wwe eS 310 Attached File Editor 313 Audible monitor 337 Audible monitor source selection 338 Audio Analyzer 123 AutoOn 20 79 101 Automating tests 351 Au
315. ilable Source A This is the audio signal as it appears at the input to the Analyzer instrument in use after ranging the point where the Channel A Level or Peak meter readings are taken If the Digital Interface Analyzer is the instrument the monitored signal is the Channel A embedded audio Source A is the same signal that is at the MONITOR OUTPUTS SOURCE A rear panel BNC connection Source B This is the audio signal as it appears at the input to the Analyzer instrument in use after ranging the point where the Channel B Level or Peak meter readings are taken If the Digital Interface Analyzer is the instrument the monitored signal is the Channel B ATS 2 User s Manual The Monitor Outputs Chapter 21 Monitoring embedded audio Source B is the same signal that is at the MONITOR OUTPUTS SOURCE B rear panel BNC connection Function A The channel A signal as it appears after a given Audio Analyzer function is applied This is the same point as the MONITOR OUTPUTS FUNCTION A rear panel BNC Signal is only available at this point when using the Audio Analyzer instrument Function B The channel B signal as it appears after a given Audio Analyzer function is applied This is the same point as the MONITOR OUTPUTS FUNCTION B rear panel BNC Signal is only available at this point when using the Audio Analyzer instrument Source A Source B The sum of these signals Function A Function B The sum of these signal
316. ilable In some cases the beginning of a WAV file may contain audio that is un desirable for measurement In the Truncate waveform beginning field you can enter the length of the initial audio to exclude Enter the length in time seconds or by specifying the number of samples Click OK The audio data will be imported into the selected buffer MATLAB support MATLAB is a technical computing environment used in DSP design and analysis MATLAB is a product of The Mathworks Inc who can be reached at 508 647 7000 or on the Web at http www mathworks com Two MATLAB functions supporting Audio Precision formatted wave files for use with ATS 2 have been provided as an aid to our customers who also use MATLAB ap write wave generates AP wave files from within MATLAB and ap_read_wave imports such files into MATLAB for fur ther manipulation These functions are provided as MATLAB files file name extension m on the Audio Precision Resources Disc and are also available on our Web site at ap com ap_write_wave Syntax 2p Wreiee wave Eilename sample rave morme lie daa Ap WES Wave End senple rate NOrmaluae daa Description ap write wave generates a binary waveform file that can be loaded into Audio Precision hardware Files with extensions agm mono genera tor waveform and ags stereo generator waveform are supported The AP waveform file format consists of a 256 byte header containing sample rat
317. ilters The sample rate must be be tween 6750 Hz and 262144 Hz All zeros must be on or inside the unit cir cle and all poles must be inside the unit circle All coefficients must be in the range 2 2 Examples 1 Compute a Chebyshev high pass filter with a corner frequency of 200 Hz and a passband ripple of 0 1 dB for three common sample rates tor sr 32000 44100 480001 ala e T OST La ajo veses iti eesi es ib leerse 200s dat 200 lala ias oy las moaiss Se 2 10 ue end We use the zero pole gain form for accuracy and the append mode to attach the three sample rates to the same file 2 Compute a voice band boosting filter at two sample rates Use the file handle method to write to the output file ATS 2 User s Manual 405 Appendix D User Downloadable Filters MATLAB Downloadable Filter Support 406 Olp open e tiltersivolce abw we fprintf ofp Voice band filter designed in MATLAB by yulewalk n n for s 15000 65536 b a y lewalk 2 0 500 1000 410008000 sr 21 e472 710 5 07s OS DSZ elo Macs ta ec Oo ip MO MOS Osio ten E Sis se lO e end close OLD Here we have the flexibility to write comments to the output file pre ceded by the identifier which will not appear inside ATS Note that it is the user s responsibility to create a file with the appropriate extension and to properly close the file ap_read_filter Syntax ae ere atadas ab On ap read re len ae
318. ime FAIL message and a list of the failed point values 364 ATS 2 User s Manual The Configuration panel Chapter 25 Configuration and the Utilities Menu The Log configuration page enables you to set Log file options for ATS These are m Enable Logging Check this box to enable logging Type the filename and path of the log file The ATS default is log alg with a path of C Documents and Settings username My Documents Audio Precision ATS n nn m Include in Log File Error Messages If this box is checked any Windows or ATS error messages that occur during the logging period will be written to the log file File I O Activity If this box is checked a text message will be written to the log file for every disk file opened and every file saved to disk The message includes the name and full path of the file and the date and time at which it was saved or opened m Sweep Activity Test Name If this box is checked the filename and full path of the executed test is written to the log file Graph Title Time and Date If this box is checked the graph title date and time of the test are written to the log file Pass Fail Message If this box is checked an error summary message will be written to the log file each time a test is run The message will say PASS or FAIL followed by the number of measurements below the lower limit the number of measurements above the upper limit and the number of timeouts which occurred m Sweep
319. in memory showing information about the display of that trace and providing drop down lists to modify some of the display parameters If a limit file has been loaded the limit traces appear in the Legend as well The Legend columns are m No Title The leftmost column selects which Data rows are plotted as traces on the graph Selected rows show an X in this column The title box for this column is blue when the Graph Legend is selected and gray otherwise a Sweep When more than one sweep is in memory in cases of appended sweeps or nested sweeps this column identifies the trace or traces associated with each sweep The sweeps are numbered sequentially m Trace When more than one set of data is associated with a sweep in cases where Data 2 through Data 6 are used each data set will produce an additional trace The traces are numbered sequentially for each sweep The trace numbers correspond with the sweep data numbers m Color The Color column shows the color currently assigned to each trace and offers a drop down list so that you can change a trace s color m Line Style The Line Style column shows the line style currently assigned to each trace and offers a drop down list so that you can change a trace s line style m Thickness The Thick column shows the line thickness currently assigned to each trace and offers a drop down list so that you can change a trace s line thickness Thicknesses greater than 1 can only
320. in the Burst On field to set the duration of the tone burst The maximum Burst On duration is 65 535 cycles of the sine waveform if Interval is set to its maximum the minimum is 1 cycle Burst On can be set in units of Cycles or s B seconds Burst Only Burst On durations which are less than the Interval durations can be entered Interval Enter a value in the Interval field to set the period between the onset of the tone burst and the onset of the next burst The maximum Interval is 65 536 cycles of the sine waveform the minimum is 2 cycles Interval can be set in units of Cycles or s B Interval does not describe the time between the end of a burst and the beginning of the next but the entire period from the beginning of one burst until the beginning of the next Low Level When a tone burst is ON the level of the sinewave in the burst is the same as the current Amplitude setting for the Digital Generator When a tone burst is OFF the low level is the ON level multiplied by the value set in the Low Level field The OFF level is a ratio of the ON level set here in units of X Y ratio dB per cent or PPM See Ratio Units page 378 If Low Level is set to equal the burst high level amplitude no burst effect will occur and the output will be a continuous sinewave At large amplitude ratios the amplitude resolution of Low Level becomes poorer The display will show the actual available resolution steps rather than the value enter
321. ine The dark line represents the phase response curve In ATS you can measure either the absolute phase relative to the gener ator or the phase difference between Channel B and Channel A See Phase Measurements page 230 The ATS Response Multitone Measurement selection provides a re sponse curve as shown in Figure 183 220 ATS 2 User s Manual Multitone Measurements Chapter 13 The Multitone Audio Analyzer 100 200 Figure 183 Typical Multitone Response measurement amplitude vs frequency Distortion Figure 184 Example of a CHEE multitone distortion response graph F1 F2 F3 F4 F5 F6 F7 F8 In a conventional distortion test where only a single tone is in the stimu lus only that fundamental frequency needs to be removed What s left is the total harmonic distortion and noise For a multitone distortion reading using our example waveform the bins containing tones F1 through F10 are rejected from the reading as shown by the dotted lines in Figure 184 The residual is the noise and distortion products shown as light gray lines The values in these residual bins are rss root sum square summed between sweep steps and a distortion re sponse curve the dark line is drawn through these results for display A typical display of an ATS Multitone Distortion measurement is shown in Figure 185 ATS 2 User s Manual 221 Chapter 13 The Multitone Audio Analyzer Multitone Measurements ANN rin 200 Suu Hz
322. information as the data file in a text table ATS 2 User s Manual 239 Chapter 13 The Multitone Audio Analyzer Creating Multitone Waveform Files 240 ASCII Waveform statistics file s wfs This is a text listing of statistics concerning the waveform files created m ASCII Sweep Table statistics file s sts This is a text listing of statistics concerning the sweep table file created Retain agm files when making Stereo files When making a stereo generator waveform file this option enables you to also generate two mono files each containing the waveform information for one channel Frequencies Menu Figure 201 ATS 2 Multitone Creation Utility Frequencies Menu dialog box Fill in the following fields to define the waveform Start Frequency 20 Stop Frequency 20000 Number of Frequency Spacing frequencies Log 37 Linear core First define the range of your multitone signal Enter the lowest fre quency in the Start Frequency field and the highest in the Stop Fre quency field Select Log or Linear Frequency Spacing and set the Number of Frequencies by entering a positive integer in the field Editing the Frequency List Click OK when you have made your settings The Multitone Creation Utility will open the Data Editor displaying the frequencies you have de fined and also the Edit Waveform Definition Menu as shown in Figure The first three buttons on the Edit Definition Menu affect a
323. ing it entirely The Floor setting provides this protection Whenever the value set in the Floor field is larger than the product of the measured signal and the Tolerance percentage the algorithm uses the Floor value instead of wait ing for the signal to satisfy the Tolerance criteria For example with a Tolerance of 1 and a Floor setting of 1 pV the Floor takes over when the measured signal drops to 100 pV The default values of Floor for each ATS meter are chosen to be ap proximately the resolution of that meter on its most sensitive range Since resolution increases as the reading rate slows it may be appropriate to change the default Floor values when the reading rate is fixed at a specific value Settling Issues for Specific Instruments Settling for each meter in ATS is independently controlled by its own row of fields on the Settling panel Audio Analyzer Reading meter settling values are stored independently for each Audio Analyzer mode For example the settling values for Audio Analyzer Amplitude A and B are independent of the settling values for Audio Analyzer THD N Amplitude A and B The Audio Analyzer Phase mode has no Tolerance field The accept able variability for this meter should be entered in the Floor field in de grees An entry of 10 00 deg for example sets a 10 degree wide window of acceptance for the selected algorithm to use in calculation Timeout It is possible with extremely noisy signals that
324. ion Dut Ohms BalXLR C 40 150 References Freq 1 00000 kHz dBr 387 3 rei watt 8 000 Ohms dEm 600 0 Ohms The Analog Generator panel is divided into three areas m The upper area which provides fields for choosing waveforms setting amplitude and attaching EQ curves m the center area which provides controls for bandwidth and output configuration and m the lower area which provides fields to set references We will first look at general topics of setting frequency and amplitude and turning the generator ON and OFF then we will examine the many waveform selections available in detail then we will look at configuring the analog outputs and setting the analog references ATS 2 User s Manual The Analog Generator Panel Chapter 8 The Analog Generator Frequency Units Figure 42 Setting the Analog Generator Frequency W Track A Frequency may be expressed in absolute units hertz and in a variety of units relative to the value entered in the Reference Freq field See Ana log Generator References on page 95 and Frequency Units on page 372 Changing units does not change the frequency of the generator The ex isting frequency will simply be re stated in the new units Also the value displayed after pressing Enter may differ slightly from the value you typed in since ATS will step to the nearest frequency increment Output On Off and Channel Selection Figure 43 Analog Generator On
325. ion buffer Audible Monitoring in the Digital Interface Analyzer It can be useful to listen to the audio on the digital interface signal being measured enabling you to make a quick confidence check It can also help you determine if the errors being measured correspond to the particu lar audible defect detected When the Digital Interface Analyzer is selected as the Analyzer instru ment the audio embedded in the digital interface signal appears at the Source A and Source B selections on the Headphone Speaker panel and at the SOURCE A and SOURCE B MONITOR OUTPUT BNCs 212 ATS 2 User s Manual The Multitone Audio Analyzer Introduction The Multitone Audio Analyzer is a DSP instrument selection on the Ana lyzer panel It is an FF I based analysis instrument for use with both analog and digital audio signals Multitone is called Fasttest on instrument browser lists and in AP Basic macro references Figure 172 The Multitone Audio Analyzer ATEN panel FASTTEST Multitone Audio Anal 0 00000 Digital Gen O 00000000s 100 0 mFFS 100 0 mFFS 1 00000 kHz ATS 2 User s Manual 213 Chapter 13 The Multitone Audio Analyzer Overview Multitone Testing Overview Multitone Testing The Multitone Analyzer uses a synchronous FFT to analyze a special multitone waveform that is a combination of many sinewaves Figure 173 shows the spectrum of a signal made up of 36 tones For more information about synchronous FFTs and ot
326. ion of a stereo waveform If the File gt Save As gt Mono Waveform option was selected the right half of the dialog will be gray You can save the entire acquisition record or just the portion currently designated for transformation from either the channel A or channel B ac quisition data If the transform length is shorter than the acquisition record length the waveform file will be correspondingly smaller Opening Acquired Waveforms Figure 148 ATS Spectrum Analyzer EERE Open Stereo Waveform dialog box S O y 184 ATS 2 User s Manual Acquired Waveform Files Chapter 11 The Spectrum Analyzer To open an acquired waveform file select the File gt Open menu com mand choosing either the Stereo Waveforms aas or Mono Wave forms aam as the file type You can load one waveform or simultaneously load both waveforms into memory from a stereo file and you can choose to assign the wave form to either FFT channel and to the acquisition or the transform buffers A mono file only contains one waveform but you have the same flexibility to load it into either channel or either buffer When opening a mono wave form file the right half of the dialog box will be gray If acquisition in a file to be opened is greater than the length of the specified buffer an error warning will be displayed and the file will not be opened If the acquisition length in the file is shorter than the buffer size erroneous analysis will resu
327. ions These list selections are for the most part sorted by the shape of the waveform such as sinewave squarewave noise and so on Most wave form choices have an associated secondary list from which you make your final waveform selection This chapter organizes the waveforms by shape The variations avail able on the secondary lists are described under each section Sine waveforms This section describes the sine waveforms available to the Analog Gener ator which cover the frequency range from 2 Hz to 60 kHz See page 94 for information on setting the Analog Generator bandwidth Sinewave fre quency can be set in hertz or in a variety of relative units see Frequency Units page 372 Figure 46 Analog Generator Sine Waveform Selections i Aaa Frequency 1 00000 k Wa Phase Shaped Burst EQ ATS 2 User s Manual 81 Chapter 8 The Analog Generator Choosing an Analog Generator Waveform Wfm Sine Normal Figure 47 Analog Generator Sine Normal ENTERAN 20 0000 kHz The normal sine waveform is the standard waveform for most audio test ing and is the default generator waveform Wfm Sine Var Phase Figure 48 Analog Generator E Analog Generator Sine Var Phase re zivar z 1 00000 kHz 0 00 deg This choice produces the selected frequency at both Channel A and B outputs but the phase of the Channel B output is variable from 180 to 179 99 with respect to the Channel A output as co
328. ircumstances depending upon the variability of the readings and the Settling settings Settling cannot be satisfied and no data for that step will be forwarded to the Regulation panel The Timeout field enables you to enter a time interval beyond which regulation will not wait for a settled reading When a reading times ATS 2 User s Manual Chapter 24 Regulation out the most recent stream of up to 32 readings from the instrument will be averaged and used as input to regulation Once you have made all your settings click the Regulate button to per form regulation Check Regulate at each sweep step to set the automatic option for sweep operation Examples of Regulated Sweeps Here are several applications of regulated sweeps m Using Regulation to hold power amplifier output distortion constant at 1 0 for example by varying generator amplitude but plotting amplifier output power versus generator frequency to produce a graph of power bandwidth Using Regulation to find a 3 dB point on a DUT then making a single point sweep to display the measured frequency at that point m Using Regulation to hold the modulation percentage or deviation of a preemphasized broadcast transmitter constant while measuring and plotting THD N versus frequency m Using Regulation to hold the modulation percentage the deviation of a preemphasized broadcast transmitter constant while measuring and plotting the generator amplitude versus freque
329. is Manual aaa aa a a a a a a 2 ATS 2 Capabilities 3 Conceptual Architecture of ATS 2 4 Other Documentation for ATS 2 5 Getting Started with ATS 2 5 Online Help 6 The AP Basic User s Guide and Language Reference 6 The AP Basic Extensions Reference for ATS 2 7 Application Notes and TECHNOTES 7 GPIB Documentation for ATS 2 7 Chapter 2 The ATS Control Software 9 Overview 0 2 00 ek a a 9 The User Interface 00800 eee eee 9 The Workspace 0 00 cee ee ee eee 10 The ATS Panels 0 000 eee ee ee ee ee 10 PanelSettings 0 0000 eee ee eee 11 PanelReadings 0000 eee eee ene 12 The ATSMenus 2 000 eee ee eee 13 The FileMenu 000 eee ee aa 13 The Edit Mena 14 The View Menu 00 000 ee eee ene 15 The Panels Menu 16 ATS 2 User s Manual The Help Menu 2 2 2 2 ee ee ee 18 Access to the Audio Precision Website 19 The Status Bar socios 19 The Toolbars and ATS Icon Buttons 19 The Standard Toolbar 20 The Panels Toolbar o oaoa a a a a a 22 The Macro TO0lbar 23 The Learn Mode Toolbar 23 The Quick Launch TO0lbar 24 ATS Add INS 000 a a ee eee 2
330. is essentially identi cal to the Analog Generator Sine Shaped Burst signal and both are similar to the Digital Generator Sine Burst signal ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator Figure 82 An example of a shaped burst For both generators the Sine Shaped Burst has a raised cosine shaped envelope creating a relatively narrow energy spectrum around the sinewave frequency The Digital Generator Sine Burst has a rectangular envelope with fast rise and fall times and consequently a wider spectrum of energy Refer to Tone Bursts page 109 for information on making tone burst settings Wfm Sine EQ ae Digital Generator Piel ES wae Fine Sine eo Frequency 997001 kHz a ae a ChE Figure 83 Digital Generator Sine EQ Auto On T Track A C Invert EAA utruTs Bee RB inver 1 000 FFS Amplitude 21 000 FFS EQ Curve 1 000 FFS a Post EG 1 000 FFS Generator Equalization The Sine EQ setting outputs a normal sinewave with equalizing ampli tude changes made in the generator level according to an attached EQ data file This enables you to make a frequency sweep where the generator amplitude varies as instructed by the data in the attached file When you select Sine EQ and attach an EQ file see below a new field named Post EQ appears on the Digital Generator panel The Post EQ field displays the generator amplitud
331. istograms of interface amplitude interface rate interface bit width and jitter amplitude The Digital Interface Analyzer uses FFT analysis techniques that have much in common with the techniques discussed in Chapter 11 Also see Appendix C for a conceptual overview of FFTs 188 ATS 2 User s Manual Loading the Digital Interface Analyzer Chapter 12 The Digital Interface Analyzer Loading the Digital Interface Analyzer Analyzer INTERYU Digital Interface Analy Audio Analyzer FFT Spectrum Analyzer INTERYU Digital Interface Analyzer h oi FASTTEST Multitone Audio Analyzer Harmonic Distortion Analyzer To use the Digital Interface Analyzer first open the Analyzer panel The Analyzer panel is a command selection on the Panel menu and is also ig available by the keyboard shortcut Ctrl Y or by clicking the Analyzer button on the Toolbar Figure 149 Loading the Digital Interface EESE 5 x Now select INTERVU Digital Interface Analyzer from the list on the Analyzer panel This loads the Digital Interface Analyzer program into DSP The Digital Interface Analyzer panel Figure 150 BA Analyzer 101x The Digital Interface Analyzer panel INTERYU Digital Interface Analy Interpolate Stable Bits Blackman H arris Analog Gen M Poniaente M Poania 1 00000 kHz Unlike the other Analyzer instruments the Digital Interface Analyzer panel has no real time meter displays Although a number of settings and
332. ith a reference frequency of 1 kHz and a measured fre quency of 950 Hz the d value is 5 dPPM delta parts per million The dPPM unit is 1 000 000 times the ratio of dHz or F R to the reference frequency R dPPM 1 000 000 E For example with a reference frequency of 1 kHz and a measured fre quency of 1 001 Hz the dPPM value equals 1 000 dPPM Phase Unit deg degree The degree is the basic unit of phase measurement repre senting 1 360 of a complete revolution of phase Time Units sec seconds Seconds are the basic time unit abbreviated s At values common in audio the display may be in ms milliseconds us microsec onds or ns nanoseconds Ul unit interval The unit interval is a convenient unit when examining digital interface signal timing because by definition the UI is relative to the signal you are measuring it scales with the interface data rate The UI is de fined as the shortest nominal time interval in the coding scheme For an AES3 or IEC60958 signal there are 2 subframes of 32 bits per frame giving 64 bits per frame after bi phase mark encoding the pulse rate is nominally 128 pulses per frame This interval 1 128 of a frame is the unit interval for AES3 and IEC60958 signals For a 44 1 kHz sampling rate 1 UI 128 x 44100 177 2 ns For a 48 kHz sampling rate 1 UI 128 x 48000 162 8 ns For a 96 kHz sampling rate 1 UI 128 x 96000 81 4 ns dBUI decibels relative
333. ity Flags display OFF black for nor mal received data and ON green for unreliable data The CRC Valid flag is ON green for valid received CRC and OFF black for invalid CRC ATS 2 User s Manual The Status Bits panel Chapter 7 The Digital I O Panel Hex Control and Display O 1 2 2 4 5 6 7 amp 3 10 11 1 12 14 15 16 17 15 19 0 1 z 2 Transmit dy s 00 00 00 OO 00 00 00 OO 00 OO 00 00 Receive 4 Tranemitg 02 00 00 99 00 oo oo oo 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Receive B 02 00 oo 00 00 00 00 00 oo 00 00 oo 00 00 co 52 20 00 00 o0 00 oo 00 7D Figure 40 Hexadecimal Display and Control of Status Bits At the bottom of the Status Bits panel are hexadecimal status bit setting fields and displays The hex codes for the channel status conditions are de tailed in the AES3 and IEC60958 standards The hex fields set white with black text and display black with green text the same status conditions as are set and displayed above in the high level English display A setting made in a high level transmit field will be echoed in the corresponding hex transmit field a setting made in a hex transmit field will be echoed in the corresponding high level transmit field To make an entry in a hex field click the cursor in the field desired and move back and forth with the arrow keys Overtype the hex code or codes shown with the new value and press the Enter ke
334. k Values Eve Pattern Four modes are available in the Digital Interface Analyzer for processing the amplitude versus time relationship of a sampled signal before display ing the waveform These modes are applicable only to time domain oscil loscope views and have no effect on Digital Interface Analyzer spectrum analysis or histogram views The display processing setting determines how the data is modified for display when the spacing of the sweep points is different from the spacing of sample points in the acquisition 202 ATS 2 User s Manual Digital Interface Analyzer panel settings Chapter 12 The Digital Interface Analyzer The four modes available in the Wave Display field are m Interpolate Display Samples a Peak Values m Eye Pattern Interpolate Display Samples and Peak Values offer the same wave display processing as do those choices in the Spectrum Analyzer Interpolate When Interpolate is selected the DSP compares the density of sweep points requested with the density of sample points available in the acquisi tion for the time span of the current sweep and graph If the requested points are much fewer than the acquisition points the DSP uses a bipolar peak sensing mode to eliminate potential graphic aliasing problems otherwise it interpolates In the bipolar peak sensing mode the signal waveform is not faithfully represented but is replaced with an approximation indicating the positive and negative peak
335. l Copy to Sweep Panel Optimize Individually Optimize Together Optimize Left Only Optimize Aight Only Display Cursors Scroll Bars Title and Labels Comment Graph Butter Zoomout Choose Zoomout to reverse the last Zoom operation and reduce the magnification of the graph If you have Zoomed repeatedly clicking Zoomout repeatedly will back you out of your Zoom operations one at a time ATS 2 User s Manual 287 Chapter 16 Graphs The Graph Options Menu If you are viewing batch mode data the Zoomout command will also send the Sweep Reprocess Data command following the same behav ior as with the Zoom command Zoomout to Original Choose Zoomout to Original to return to the original graph sizing and coordinates in one step If you are viewing batch mode data the Zoomout to Original com mand will also send the Sweep Reprocess Data command following the same behavior as with the Zoom and the Zoomout commands Optimize The Optimize graph option is a method of zooming or magnifying the scale of the graph relative to the signal currently on the graph An opti mized graph will replot with new Y axis coordinates for a maximum resolu tion display of the signal Although you can optimize your graph at any time it is usually most ef fective to optimize after the conclusion of a sweep There are four Opti mize choices a Optimize Individually This option is only available if both Y axes are in use displaying da
336. l data rate so the rate per output is 1 2 OSR m Dual XLR 2xOSR Similar to Dual XLR with this difference the Sample rate OSR field sets the data rate per connector so the overall data rate is 2x OSR All the digital outputs are always active Signal voltage levels at the bal anced and unbalance outputs are related by a 4 1 ratio both will change when either is adjusted Dual Connector Mode Typically the alternate data subframes in the AES3 signal carry the left and right audio channels In the Dual XLR mode each AES3 inter face signal carries a monaural signal whose sub frame rate is double the frame rate Two connections I and II are required for 2 channel audio Normally Connector I carries the A or left audio channel and Connector II carries the B or right audio channel ATS 2 User s Manual 53 Chapter 7 The Digital I O Panel The DIO Output Section 54 Output Sample Rate OSR Figure 17 The DIO Sample rate OSR and Sample rate O SR 48 0000 kHz e Voltage selections Voltage 5 1 D0 Spp The Sample rate OSR field labeled Rate on the small form of the DIO panel allows you to set a value for the output sample rate or OSR The default OSR is 48 kHz Simply click on the field and enter a new rate from the keyboard The OSR may be set in the range between 28 8 kHz to 108 kHz in Dual XLR mode the range is 57 6 kHz to 216 kHz A drop down list allows you to specify the units of measurement for t
337. l 187 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Components The optional Digital Interface Analyzer provides additional capability adding powerful interface signal acquisition and analysis tools that are dis cussed in this chapter See Appendix B for a discussion of digital audio and the serial digital in terface signal Digital Interface Analyzer Components The Digital Interface Analyzer includes two key components a dedi cated analog to digital converter ADC connected to the digital input and specialized FFT analysis and display tools The Digital Interface Analyzer ADC The dedicated Digital Interface Analyzer ADC digitizes the interface waveform as it enters ATS 2 providing a source of acquisitions for the Digi tal Interface Analyzer FFT analysis The ADC is an 8 bit converter with an 80 00 MHz sample rate providing an analysis capability with approxi mately 30 MHz bandwidth The Digital Interface Analyzer acquires 1 572 864 samples into its FFT acquisition buffer resulting in 19 66 ms of data Digital Interface Analyzer Capabilities The Digital Interface Analyzer provides analysis results in three different types of displays m time domain waveform displays including interface signal waveforms interface signal eye patterns and jitter signal waveforms m frequency domain displays including interface signal spectrum and jitter signal spectrum and m statistical displays including h
338. l A You can change the associa tion at any time using the Bar Graph Setup panel discussed below Figure 236 Creating a Bar Graph by 90 00 us right clicking the By ele mouse Another way to make a new Bar Graph is to right click the setting or reading field in which you are interested and click Create Bargraph from the menu which appears Bar Graph Setup Click the Setup button to access the Bar Graph Setup panel The Setup button may not be visible if the Bar Graph panel is sized too small Figure 237 Bar Graph Setup EAEG did ca ro E E 1 000 FFS Iv 10 00 uFFS foors EE 10 00 uFFS 10 00 mFFS gi 304 ATS 2 User s Manual Using a Bar Graph for Readings Chapter 17 Bar Graphs At the top of the Bar Graph Setup panel is a Connection browser simi lar to the instrument browsers at Source and Data in the Sweep panel You can select the instrument and setting or reading parameter for this Bar Graph using the Connection browser Checkboxes allow you to Display Digits Only or toggle the Com ment display Target Range displays a dark bar on the Bar Graph to give a visual indi cation of a range of interest You can turn the Target Range display on or off by checking the Range On checkbox Set the extents of the Target Range in the Lower and Upper fields in this area Target Range is enabled only on a Bar Graph configured for readings In the Axis area you can set up the range of the Bar Graph display o
339. l Generator References References Wolts FS i O00 Y Freq 397000 kHz dEr 387 3 mFFS Volts for Full Scale Reference Digital full scale FS is defined as the rms value of a sinewave whose peaks just touch the maximum values of the coding scheme When ex pressed in analog domain units there must be a reference given to estab lish the level relationship between the two domains For Digital Generator settings that reference is entered as the rms voltage which is to correspond to a full scale digital audio signal Set the Digital Generator volts for full scale reference in the Refer ences Volts FS field Frequency Reference The relative units of measurement for the Digital Generator are F R dHz Hz cent octs decs d and dPPM In a relative expression the frequency setting or reading is expressed in relation to a second reference frequency For Digital Generator relative fre quency settings this reference frequency is entered in hertz in the Digital Generator References Freq field dBr Reference The dBr which is shorthand for decibels relative to a reference refer ence is an easy way to set a nominal level against which your settings or readings are made Enter a reference value in the References dBr field You can set a Digital Generator dBr reference in FFS FS dBFS bits V Vp Vpp dBu dBV dec or hex units ATS 2 User s Manual Chapter 10 The Audio Analyzer Overview The
340. l generators This feature enables you to use an external signal as the generator waveform See Wfm Special Pass Thru on page 93 for the Analog Generator or page 116 for the Digital Generator Sync Ref Input Panel Figure 269 The Sync Ref Input panel Sync Ref Input Aa ES Source AREA EE l Frame Lock C HIZ 75 Ohms Frequeney 42 0000 kHz Input Frequency He Out of Range Two settings are required to synchronize ATS 2 s master clock to an ex ternal source m Select the format of the external sync signal in the Source field m Enter the exact nominal frequency of the external sync signal in the Frequency field In addition to these settings the Sync Ref Input panel enables you to set termination impedance options and select the Frame Lock option for dig ital audio reference signals There is also an Input Frequency display field and an Out of Range indicator to provide you with more informa tion as you make the synchronization settings A master ON OFF button allows you to enable and disable synchronization These settings and dis plays are discussed in detail below Reference Input Source Figure 270 The Reference Input Source MENE le ES list Reference Input Source ses Syne Rate aie orr AES Sune Hate Fra Squarewave NTSC Video Syne Horz Rate PAL SECAM Video Sync Horz Rate ATS 2 User s Manual SYNC REF IN Chapter 22 Sync Ref Trigger and Aux Select the format of the externa
341. l synchronization signal from the Source list AES Sync Rate This selection will synchronize the ATS 2 master clock to the sample rate of a properly formatted AES3 or IEC60958 signal applied to the SYNC REF IN BNC This choice synchronizes the sample rates but does not ensure that the signal frames are aligned in time To align the frames the ATS 2 digital output signal must be set to the same sample rate as the reference signal and the Frame Lock box on the Sync Ref Input panel must be checked m Squarewave This selection will synchronize the ATS 2 master clock to a TTL squarewave signal or other periodic signal applied to the SYNC REF IN BNC This signal may be between 8 kHz to 10 MHz A bit clock output from a digital device applied to the SYNC REF IN connection in Squarewave mode will synchronize the ATS 2 sample rate to the device sample rate See Squarewave frequency ranging below m NTSC Video Sync Horiz Rate This selection will synchronize the ATS 2 master clock to the horizontal sync pulse nominally 15 7343 kHz of an NTSC analog video signal applied to the SYNC REF IN BNC PAL SECAM Video Sync Horiz Rate This selection will synchronize the ATS 2 master clock to the horizontal sync pulse nominally 15 6250 kHz of a PAL SECAM analog video signal applied to the SYNC REF IN BNC Squarewave frequency ranging To cover the wide frequency range ATS 2 performs automatic fre quency range switching when Squarewave is selected
342. le rate Fy 2 There are four pairs of meters on the Harmonic Distortion Ana lyzer which measure the input signal simultaneously The Fundamental Amplitude meters These meters display the signal amplitude at the selected fundamental frequency The frequency that the Harmonic Distortion Analyzer identifies as the fundamental is determined by the selection made in the Steering Control field discussed below u The Fundamental Frequency meters These meters display the frequency of the highest amplitude component of the applied signal These frequency meters or counters are only enabled when Counter Tuned is selected in the Steering field a The Harmonic Sum 1 meters These meters display the sum of the amplitudes of the harmonics selected in the Harmonic Sum 1 fields and u The Harmonic Sum 2 meters These meters display the sum of the amplitudes of the harmonics selected in the Harmonic Sum 2 fields As on other ATS panels you can select the units of measurement you prefer for each reading display 246 ATS 2 User s Manual Loading the Harmonic Distortion Analyzer Chapter 14 The Harmonic Distortion Analyzer The two Harmonic Sum readings will correctly sum and display only the distortion products which are within the bandwidth limitations determined by the sample rate See page 249 for more information on bandwidth limitations Loading the Harmonic Distortion Analyzer Figure 205 Loading the Harmonic Analyzer Disto
343. le rate ATS 2 offers the capability to scale the embedded frequency relative to the interface output or input sample rates In the output Scale Freq by field you can select one of three sample rate choices as a reference by which to scale the embedded frequency of the digital output signal The choices are Output Rate which is the rate set in the Sample Rate OSR field above m Meas Input Rate which is the measured input sample rate displayed on the Input side of the DIO panel m DIO Rate Ref which is a reference value you can enter on the Input side of the DIO Polarity Figure 21 The DIO Polarity selection Polarity To lever The polarity of the serial digital interface bitstream output can be re versed by checking the Invert checkbox Properly designed AES3 receiv ers should function correctly with either polarity of input bitstream Send Errors Four bits are sent at the end of each frame of AES3 IEC60958 data the Validity bit the User bit the Channel Status bit and the Parity bit See Ap ATS 2 User s Manual 57 Chapter 7 The Digital I O Panel The DIO Output Section 58 pendix B for more information about Status Bits and the AES3 IEC60958 interface ATS displays and sets the Status bits on the Status Bits panel page 70 User bits are not displayed or set in ATS The states of the output Validity bit and the Parity bit can be changed on the DIO panel Figure 22 The DIO Send Errors selections
344. le to ATS through the AP Basic lan guage A macro has been created to give you easy access to the Start On Rules On the ATS Menu bar click File gt Open gt Macro and select the file xstart onrules atsb Then on the Menu bar click Macro gt Run The fol lowing dialog box will appear Figure 220 External Sweep Start On Rules Panel Sets External Sweep Start On rules Default setting starts sweep when the Source meter reading is within the Start Spacing field settings This setting is not saved with the test Itis global and apples to ALL external tests until changed or ATS ts restarted Current Start On setting ls indicated START OM RULE Starts Sweep when Sourcel meter reading is f Beyond the Start setting f Any settled reading Selection of a Start On Rule remains in effect until a new selection has been made or until the ATS control software has been closed The default Start On Rule is Within Start Spacing settings In an external sweep the Go button enables the acquisition of sweep measurements however no data will be acquired until the externally gener ated signal satisfies the conditions set by the Start On rule which is in ef fect There are three Start On rules ATS 2 User s Manual 275 Chapter 15 Sweeps and Sweep Settling External Sweeps 276 m Within Start Spacing settings The sweep starts on a settled reading that is above the Min Lvl value and that is als
345. left or right Y axes with either Data 1 or Data 2 Consequently the Data 3 through Data 6 sections of the Sweep panel have no Top and Bottom or scaling fields ATS 2 User s Manual Sweep Display Mode Chapter 15 Sweeps and Sweep Settling To share a calibration scale with Data 1 or Data 2 the measurements must be of the same measurement domain For example dBV dBM V and W are all of the same measurement domain all being based on volt age measurements Phase measurements or digital data measurements are not of this measurement domain and cannot be plotted against the same calibration scale as voltage Of course all data in a sweep is always available in the Data Editor and can be viewed in a tabular form regardless of measurement domain Data that cannot be plotted due to measurement domain conflicts will be dis played in the Data Editor in the base unit for that measurement domain Here s an example if Data 1 is percent distortion and Data 2 is level it will not be possible to also plot phase on Data 3 If however you wanted to plot channel A and B level and the phase difference between them you could assign channel A level to Data 1 phase to Data 2 and channel B level to Data 3 The Data 3 measurements would be plotted against the left hand Y axis calibration set in Data 1 Sweep Display Mode When ATS makes a sweep the results can be displayed as a graph as a table or both Click the Create Graph and or Crea
346. ll the fre quency selections in the Data Editor Randomize Phase values To help minimize the waveform crest factor this command randomizes phase values This is the same as one iteration of the Minimize Crest Factor function ATS 2 User s Manual Creating Multitone Waveform Files Chapter 13 The Multitone Audio Analyzer fs Data Editor O x m 0 Analog Generi Analog Gener Analyzer Phas Randomizing Phase values can reduce the waveform crest factor Randomize Phase values Set Phase values to 0 0 deg Set all Magnitude values to 0 0 dB Edt Data values Cancel 20 0010 kHz Figure 202 ATS 2 Multitone Creation Utility Edit Waveform Definition Menu dialog box m Set Phase values to 0 0 deg This sets all phase values to 0 0 dearees a Set all Magnitude values to 0 0 dBV This sets all tone amplitudes to 0 0 dBV m Edit Data Values This command gives you access to the Data Editor where you can edit the waveform data adding or deleting rows and changing frequencies amplitudes and phase values If you add new frequencies using Edit Data Values be sure that the frequencies you choose are synchronous See Appendix C for a discussion of synchronous FFTs When you are done editing the data click OK Sweep Table Definition If you have requested a sweep table a dialog box will open to enable you to define the frequencies listed in the sweep table Your options are as follows Fundamental Fre
347. lled you have the choice terminating the input in a load of either 100 kQ or 600 Q This termination choice affects both the balanced and unbalanced inputs Peak Monitors Beneath the Source selection fields are two peak reading monitors one for each input channel These monitors read the peak voltage of the ana log inputs to confirm signal presence and to aid you in setting the input ranging if necessary 46 ATS 2 User s Manual Input Ranging Chapter 6 The Analog Input Panel Input Ranging Practical devices have an optimum amplitude operating range in which they exhibit their best performance This is true for amplifiers for measure ment instruments and for the ADC circuits used in ATS 2 domain conver sion ATS 2 uses selectable attenuators and gain amplifiers to bring a wide range of input signals to the optimum amplitude for the measurement de tectors ATS 2 gives you the choice of automatic ranging or autoranging or manually setting a fixed maximum range Analog input ranging is controlled from the Analog Input panel If you are using the Audio Analyzer instrument additional Analyzer ranging controls are available on that instrument as explained on page 129 Autoranging ATS 2 should normally be operated with automatic ranging indicated by a check mark in each the appropriate Auto Range check boxes This provides operation with no possibility of clipping due to high amplitude sig nals Click the Auto Range check
348. lp ONlINe 6 HI 2 harmonic weighting filter see weighting filter High bound Regulation parameter 357 Highpass filter see bandpass filter Histogram Digital Interface Analyzer 197 Hotkeys 248 27 IEC60958 384 IRM ku iaa oA sara 401 ATS 2 User s Manual IMD measurements Audio Analyzer IMD waveforms Import acquisition from WAV file Independent variable Infinite impulse response filter Input sample rate see ISR Interchannel Phase measurements see phase measurements Intermodulation Distortion see IMD Internal vs external sweeps interpolate FFT display processing Intervu see Digital Interface Analyzer InterVuMenu atsb Invalid multitone readings IVE ot ee oS ee eae ee EO S Invert Compute algorithm ISR Iterations Regulation setting J index Jitter detection Digital Interface Analyzer clock squarewave signal digital interface signal Jitter histogram Digital Interface Analyzer Jitter waveform Digital Interface Analyzer J Test waveform K Keyboard shortcuts L L lower limit flag see Data Editor lower limit flag Labels graph 2 Sewer ewe w SE as Learn mode enter exit Learn Mode toolbar Legend Data Editor linkage Legend graph Level meters Audio Analyzer Level monitors Spectrum
349. lso sets the parameters for External Sweeps and sets the parameters to control FFT graphing for batch mode instruments The compact display of the ATS Sweep panel which is the left half of the panel shown in Figure 214 allows you to set up a single Source sweep with one or two sets of Data results If you expand the panel as shown above you can use two sweep Sources and up to four more Data result traces and you have access to additional controls and settings on the Sweep panel Source 1 Every sweep must have at least one sweep Source and one set of Data results The Source 1 area on the Sweep panel is where you will select and define your primary swept parameter the independent variable delib erately changed during a sweep test In a graph of a sweep Source 1 usu 258 ATS 2 User s Manual source 1 Chapter 15 Sweeps and Sweep Settling ally defines the X axis the horizontal graph axis Source 2 is used for nested sweeps which are discussed on page 269 Settings or Readings Source 1 will typically be an internal ATS setting such as Analog Gen erator frequency or amplitude It could just as well be a Digital Generator setting or a Digital I O setting such as Output Sample Rate for exam ple It is also possible to use an external signal as the swept parameter the in dependent variable In this case Source 1 is set to an ATS reading such as Audio Analyzer frequency or amplitude A sweep which uses readings for a so
350. lt if the selected FFT length extends beyond the last data sample in the buffer You can view the data in the time domain to determine exactly where the signal ends Combining Mono to Stereo To compare two single channel acquisitions made at different times or under different conditions open the file containing the first acquisition data Assign the waveform to FFT channel A or B and load the data Then open the second waveform file and do the same this time loading the data into the opposite FFT channel The resulting two channel acquisition can be transformed processed and viewed and can be saved as a new stereo waveform file Compatibility of Acquired Waveform Files The waveform files used by both the Spectrum Analyzer and the Multitone Audio Analyzer have the same format and with certain restric tions on length can be used by either instrument The Spectrum Analyzer has a larger acquisition buffer and can open waveform files up to 256k samples in length Multitone is limited to open ing files with acquisitions of 32k or fewer samples Also although any multitone waveform can be analyzed by the Spec trum Analyzer only properly formatted waveform files are useful in Multitone See Chapter 13 for more information about the Multitone Au dio Analyzer ATS 2 User s Manual 185 Chapter 11 The Spectrum Analyzer Acquired Waveform Files 186 ATS 2 User s Manual The Digital interface Analyzer Overview The Digital I
351. lt in significantly different measurements If your goals do not require measurements that extend below the audio range to DC it is usually advis able to use AC coupling to block any DC offset For analog inputs it s usually best to use the Function meters which are always AC coupled This is because the use of the Level meters in an AC only mode requires that the DC be blocked in the Analog Input cir cuitry but even with carefully chosen high tolerance components any tiny mismatch in the DC blocking capacitors can adversely affect com mon mode measurements For digital inputs either uncheck the DC checkboxes and use the read ings on the Level meters or use the Function meters which are always AC coupled The Frequency Meters Figure 107 A Analyzer TES The Audio Analyzer Instrument Audio Analyzer Frequency Meters ChA Input Analog ChB MEAN gt o E gt w Range Function Mos v tior Amplitude The frequency readings of the signals on the two channels are shown in the Freq meter fields just below the Level meter readings In ATS the fre quency meters are sometimes called frequency counters The units of measurement include m the absolute frequency in Hz and m a variety of relative frequency units F R dHz Hz cent octs decs d and dPPM 128 ATS 2 User s Manual The Frequency Meters Chapter 10 The Audio Analyzer All the relative frequency units are computed wi
352. lyzer Chapter 14 These five chapters discuss every function control and display available on each Analyzer instrument panel in detail If you are new to ATS 2 you might want to start with the Quick Guides in Getting Started with ATS 2 which will introduce you to the Analyzer instrument features Sweeps and Graphs The Analog Generator the Digital Generator the Analyzer and other ATS functions can be controlled from the Sweep Panel which orchestrates sets of measurements and provides the means to collect graph edit con strain and modify analysis data See Chapter 15 for information on using sweeps Chapter 16 for graph ing Chapter 18 to learn about limits and Chapter 19 for performing com putations on test results a E AA ATS 2 User s Manual Chapter 6 The Analog Input Panel The Analog Input panel selects and configures audio signals that are ap plied to ATS 2 s analog inputs and sets the sample rate and bandwidth of the analog to digital converters ADCs that prepare the signals for analy sis See Chapter 5 Signal Analysis and Audio Analyzer Signal In puts page 125 Click Panels gt Analog Input or the Analog Input button on the Panels toolbar to open the Analog Input panel Figure 12 The ATS Analog Input panel ALA Bal Sourc 1 Analog Input 10 iate Hihestab5536 With the exception of the Converter and Sample Rate choices the two analog input channels can be configured independe
353. make your jitter selection in the Data instrument browser The Source 1 range will vary with the frequency of the jitter signal Jit ter frequencies can range from almost O Hz to several tens of kilohertz Fig ure 154 shows a jitter sinewave with a period of about 100 us giving a fundamental frequency of about 10 kHz Source 1 Stop is set at 200 us The Data 1 range will vary with the jitter amplitude Typical jitter ampli tude ranges from 5 ns to 20 ns or more Figure 154 shows a range of 20 ns On the Digital Interface Analyzer panel Wave Display can be set to any choice except Eye Pattern See Jitter Detection on page 204 for more information 194 ATS 2 User s Manual Digital Interface Analyzer Spectrum Views Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Spectrum Views The Digital Interface Analyzer provides spectrum frequency domain views of the both the digital interface signal and the jitter signal extracted from the interface signal interface Spectrum The interface spectrum view shows a spectrum analysis of the serial digi tal interface signal covering a frequency range extending from O Hz to over 30 MHz E re 5000k 10000k 15000k Hz Figure 155 Digital Interface Analyzer interface signal spectrum analysis 48 kHz rate As indicated in Figure 151 this view requires these Sweep settings Source 1 Intervu Frequency and m Data 1 Intervu Amplitude Source 1 range should
354. mance of an interface receiver Type in the Volt age field to enter a new interface voltage ATS 2 User s Manual The DIO Output Section Chapter 7 The Digital I O Panel The XLR and BNC digital outputs are calibrated with the assumption that the signal is terminated in the proper impedance 110 Q for the bal anced output 75 Q for the unbalanced If the signal isn t properly termi nated the actual output voltage will be different from the voltage specified in the DIO panel The output voltage may be swept as part of a test by selecting Dio as the instrument and Output Voltage at Source 1 or Source 2 on the Sweep panel Output Resolution Figure 18 The DIO Resolution selections Besolutior 24 E d t Pre emphasis Scale Freg By The Resolution field shows the output resolution or word width You can set the resolution to any integer value from 8 bits to 24 bits by typing in the value and pressing the Enter key Internal to ATS 2 the digital signal is generated at a word length greater than 24 bits When a word length is selected in the Resolution field dither is added at the appropriate amplitude for that length and the signal is truncated to the specified value The output resolution is independent of the input resolution The output resolution may be swept as part of a test by selecting Dio as the instrument and Output Resolution at Source 1 or Source 2 on the Sweep panel Law and A law Compression See Figur
355. mble in the interface signal received at the SYNC REF IN input ChB Sync Ref Rcv Sub Frame A trigger transition is generated at the beginning of each Channel B subframe each Y preamble in the interface signal received at the SYNC REF IN input Sync Ref Rcv Block 192 frames A trigger transition is generated at the beginning of each Status Block frame each Z preamble in the interface signal received at the SYNC REF IN input This occurs once every 192 frames Sync Ref Rev Error Four receive error conditions in the interface waveform are defined and flagged See Error Indicators on page 68 Select the error conditions which you wish to use as triggers in the check boxes on the Main Trigger panel When any of these selected conditions occurs in the interface signal received at the SYNC REF input a trigger transition will be generated Auxiliary Control Output and Input The Auxiliary Control Output and Input ports provide the ability to trans mit or receive control signals from external devices These are general purpose 8 bit digital ports available on two 9 pin D Sub connectors on the ATS 2 rear panel and are intended for direct in terface to LSTTL circuitry or via LSTTL compatible drivers to relays Appli cations include control of mains power indicator lights annunciators and so on and reading and display of device states To set bits for the Auxiliary Control Output or view the bit states at the Input click Pa
356. measurements Limits are discussed below m Sweep atss file Sweep files are used to store data for Table Sweeps which are sweeps that get their Source data from a table rather than Sweep panel settings See Table Sweeps pace 270 m EQ atsq file EQ files are used to modify sweep measurements by computing the sweep data against the data in an EQ table See Compute Equalize page 326 Setting Limits You may want to compare a graph of a DUT s performance with an ideal device or with a published standard It is possible to append one graph to another and make a visual comparison but ATS provides a more powerful technique setting limits and performing a pass fail test To set limits in ATS you must attach a limit file to your sweep See Chapter 15 for a detailed discussion of sweeps When a measured sweep value exceeds a set limit value the measure ment is flagged as having failed the limit This flag can be viewed in the Data Editor or reported in more detail in the Log file If your pass fail test is part of an automated AP Basic macro the flag can be reported or it can be used as a trigger for some other command A limit can also be config ured to immediately stop the sweep on failure See Actions Upon Fail ure page 314 ATS 2 User s Manual Setting Limits Chapter 18 Editing Data and Setting Limits Making a Limit File Any ATS data which can be viewed in the Data Editor or saved as a data file can be a Limit File
357. ments and the precise frequency of the fundamental must be known to cal culate the frequencies of each of the harmonics to be measured The Steering control determines how the Harmonic Distortion Ana lyzer identifies the fundamental signal component The Steering control field is centered just above the References section on the Harmonic Dis tortion Analyzer The Steering control enables you to choose a source of frequency steer ing for the identification of the fundamental frequency The five selections available in this field are ATS 2 User s Manual 251 Chapter 14 The Harmonic Distortion Analyzer Harmonic Distortion Product Amplitude Counter Tuned Counter Tuned uses the measured frequency value displayed in the Fundamental Frequency field as the steering source for the fundamental and harmonic selectivity Choose this mode when making harmonic distortion measurements from an external signal such as playback of a Compact Disc or audio tape or the received signal from a distant source m Sweep Track With Sweep Track selected the fundamental frequency value tracks the frequency of whichever generator is selected in the Source 1 or Source 2 fields of the Sweep panel m AGen Track With AGen Track selected the fundamental frequency will automatically track the frequency of the Analog Generator DGen Track With DGen Track selected the fundamental frequency will automatically track the frequency of the Digital Gener
358. metimes called a rectangular window does not apply any window function before the FFT This mode is normally used only with synchronous signals it is not generally useful for non synchronous signals since energy will be spread across the entire spectrum unless the signal is exactly at bin center The maximum amplitude error due to the rectangular window attenuation is about 4 dB General purpose spectrum analysis applications such as displaying the interface signal spectrum can use the Blackman Harris window When making FFT based amplitude measurements of a discrete frequency jitter component the Flat Top window should be used See the discussions of FFT windowing in Chapter 11 and in Appendix C for more information on the window shapes and their relative advan tages and disadvantages The amplitude calibration for FFT spectrum analysis of jitter is in terms of the rms value of the jitter signal such that a 1 kHz sinewave jitter signal measured at 10 ns peak on the DIO panel and displayed as a waveform of 20 ns peak to peak in waveform display mode will have an FFT peak at 1 kHz of about 7 ns rms peak x 0 707 208 ATS 2 User s Manual Digital Interface Analyzer panel settings Chapter 12 The Digital Interface Analyzer Trigger Source Figure 168 Digital Interface Analyzer panel Source Analog Gen El Trigger Source selections E Data Acquisition Jitter Ger Receive Error Trigg Ing In Ext Line Mains I Confit C
359. mization introduced will be the same on both channels and the relative phase measurement will be valid References Analog and digital amplitude and frequency references for the Multitone Audio Analyzer are the same as for other Analyzer instruments See Ana ATS 2 User s Manual 231 Chapter 13 The Multitone Audio Analyzer Other Considerations 252 lyzer Analog References on page 151 and Analyzer Digital Refer ences on pace 152 Other Considerations Multitone Minimum Duration Requirements The minimum duration of multitone signal which must be present to guarantee analyzer triggering depends primarily upon the generator record length used to create the multitone signal The required signal duration also varies inversely with the sample rate at which the signal was gener ated and in the case of digital inputs will be received Small variations in required duration are also a function of whether the signal is acquired from an analog or the AESS serial digital source and whether or not the fre quency correction function of the Processing field is in use Lowest Freq amp Generator Pis Minimum Burst CEE Freq Length Duration Spacing 16384 ENE 292 He 9192 586 Hz 4098 11 7 234 He 469 Hz ee omw o 88 toms te 5H Table 1 Generator record length versus attributes Conditions are 48 kHz sample rate and use of Freq Corrected Table 1 shows the minimum multitone signal duration as a function of generator record le
360. mple Rate la 1920tt44 agm a 400 0 48 agm a 40012048 agm ss 400 4048 65536 laa 1920tt48 agm a 40010044 agm a 400 2044 agm a 400 6044 Configura 4 2 References File name agm ags dBr 287 3 r Files of type waveform Files agm ags y Cancel Eoo h Figure 60 Loading an arbitrary waveform The generator arbitrary waveform function allows you to load a prop erly formatted digital waveform file into the ATS 2 DSP and route the waveform to the Analog Generator outputs Arbitrary waveform files provided with ATS 2 include single tones tone combinations for IMD testing multitone waveforms and calibration tones and other useful waveforms Waveform files must be of the Audio Precision agm Generator Mono or ags Generator Stereo file types You may also make custom arbitrary waveform files using a file creation utility provided with ATS 2 or with third party applications such as MATLAB See Multitone Creation on page 236 Setting the DAC Sample Rate To load a waveform file and then output the waveform so that the em bedded audio tones are at the intended frequencies the sample rate of the Analog Generator DACs must be set to the same sample rate that was used in creating the file If you use a sample rate different from the sample rate at which the file was created the frequency of the audio tones embedded in the output sig nal will be shifted by the ratio of the two sample rates When Arb W m i
361. mple rate 20 Hz to 20 kHz at a 48 kHz sample rate The bandpass or peaking form of the filter is used in two Audio Ana lyzer functions Crosstalk and m Bandpass The bandreject or notch form of the filter is used in two other Audio An alyzer functions THD N Ratio and me THD N Ampl Either the bandpass or bandreject form of the filter may be fixed in fre quency or may be steered to automatically track a parameter during a sweep test You can select the source of frequency steering information in the BP BR Filter Freq field located in the lower right area of the Audio Analyzer panel The selections are Counter Tuned m Sweep Track m AGen Track m DGen Track and ATS 2 User s Manual 149 Chapter 10 The Audio Analyzer The Function Meters Fixed When the Audio Analyzer is using the Bandpass function you can further modify the filter steering source value by changing the setting in the Fltr field located beneath the BW bandwidth setting fields See Se lecting Harmonics in Bandpass on pace 150 m When Counter Tuned is selected the frequency value measured by the Frequency counter becomes the filter steering source You would use this when making THD N or Crosstalk measurements from an external signal such as playback of a compact disc or reception of a signal from a distant source m When Sweep Track is selected the filter tracks the frequency of whichever generator is selected in the Source
362. ms can show up as symptoms in these embedded audio measurements ATS can also directly monitor the interface signal on the Digital In put Output DIO panel which provides direct read out and control of in terface configuration format voltage resolution sample rate jitter status bits and more A more powerful tool is the Digital Interface Analyzer available as part of the ATS 2 Performance Upgrade Option This option adds an 80 MHz ADC to ATS 2 dedicated to digitizing the interface data stream for DSP analysis and enables an additional Analyzer instrument the Digital Interface Analyzer With the Digital Interface Analyzer you can measure and display the in terface waveform and spectrum create an eye pattern show the jitter waveform and spectrum and display histograms of interface amplitude in terface rate interface bit width and jitter ATS 2 User s Manual 391 Appendix B The Digital Audio Signal Serial Interface Measurements 392 ATS 2 User s Manual Appendix C FFTs The Fast Fourier Transform The Fast Fourier Transform or FFT is a mathematical technique that de constructs a complex waveform into its component sinewaves Presented with a segment of data which represents the amplitude vs time relation ships of a complex waveform an FFT will derive two sets of results the am plitude spectrum amplitude vs frequency and the phase spectrum phase vs frequency of the signal This information is suffic
363. n standard AC measurement terms including peak peak to peak average and rms were agreed upon For many purposes rms root mean square AC measurements were often the most useful especially for audio work The decision to use one or another detector is dependent on what aspect of an audio signal you are interested in measuring Different de tectors and signals with different crest factors will give you different results Crest factor is the ratio of a signal s peak amplitude to its rms am plitude Crest factor is a term describing in simple terms how peaky or smooth a waveform is A signal with many large narrow transients such as Gaussian white noise has a high crest factor a consistent waveform such as a flute tone has a low crest factor ATS 2 User s Manual 141 Chapter 10 The Audio Analyzer The Function Meters RMS The RMS choice provides conventional true rms detection with a measurement time approximately the reciprocal of the selected reading rate m Fast RMS The Fast RMS selection provides synchronous rms detection for periodic signals such as sinewaves and squarewaves making accurate measurements in as little as one cycle of signal Fast RMS is useful for very rapid frequency response sweeps The measurement period is synchronized with zero crossings of the signal waveform and will always be an integer number of signal cycles The actual measurement time is the reciproc
364. n a red typeface 308 ATS 2 User s Manual The Data Editor Chapter 18 Editing Data and Setting Limits The normal and bold typefaces alternate between sweeps or changes in sweep direction for easy identification of data sets when performing ap pended or nested sweeps These normal bold designations correspond to the normal bold designations in the Graph Legend display The Data Editor will also scroll to the first data point in a trace when the row for that trace has been selected in the Graph Legend Graph cursor lo cations are indicated in the Data Editor by highlighting the cursor cells with a light gray background See Graph Legend Data Editor Linkage page 296 Data Display Flags Data values may also be flagged with letters to indicate special condi tions B Bad indicates invalid data from Analyzer overload an invalid Multitone reading etc Instead of a measured value the Data Editor 99 shows m U Upper indicates that the measurement value has exceeded the Upper limit This condition is also marked by a red typeface See Limits on page 310 m L Lower indicates that the measurement value has passed below the Lower limit This condition is also marked by a red typeface See Limits on page 310 m T Timeout indicates that settling has timed out for this measurement See Timeout on page 283 R Regulation indicates that the attempt to regulate this data reading was unsuccessful See Regul
365. n also stop the sweep by selecting Sweep gt Stop from the Menu bar or by pressing the ESC key To pause or unpause a sweep press function key F10 Repeat You can set ATS to repeat your sweep indefinitely Click the Repeat check box on the Sweep panel to enter the Repeat mode Selecting Sweep gt Start with Repeat from the Menu bar or pressing the key combination ALT F9 sets the Repeat mode and starts the sweep When you need to interrupt repeated batch mode processing such as FFT or multitone tests do it by unchecking the Repeat box and letting the sweep completely finish If you use Stop you will leave invalid data in the DSP that will result in a meaningless graph Append You can set ATS to append your sweeps to the graph retaining your pre vious data and appending the new data to the old Normally when not us ing Append ATS clears the existing sweep data from the graph and from memory before beginning a new sweep To enter the Append mode click the checkbox on the Sweep panel Click the box a second time to remove the check and exit the Append mode Selecting Sweep gt Start with Append from the Menu bar or pressing the key combination CTRL F9 sets the Append mode and starts the sweep Appending a File You can also append previously saved data to a current sweep by using the File gt Append command which opens a file browser dialog box Se lect a test ats2 or data atsa atsq atss or atsl file t
366. n of the buffer In the example above any FFT Start Time less than 100 ms would produce erroneous data Any combination of Start Time and Length extending beyond the 271 ms point would also produce bad data Synchronous Averaging for Move to bin center operations With None move to bin center in the Window field time aligning is more complicated because of the frequency shift imposed upon the ac quired signal The two average first selections will provide faster opera tion since the move to bin center operation is only done once following all acquisitions and averaging The move center first selec tions perform the bin centering operation at each acquisition increasing the measurement time However if the signal frequency changes from acquisition to acquisition because of flutter or drift the move center first selections may provide ATS 2 User s Manual Averaging Chapter 11 The Spectrum Analyzer more accurate measurements Frequency changes during synchronous av eraging will result in amplitude errors since the signals will not be time aligned at the end of the buffer even if they are synchronized at their initial zero crossing a 17 5k 40k 22 5k Figure 140 Low level signal viewed in the frequency domain no averaging Synchronous Averaging and Frequency Domain Views As stated before synchronous averaging is performed on the signal ac quisition in the time domain Since the frequency domain sp
367. n the graph the left and right arrows move a cursor horizontally across the trace To select the other cursor press an arrow key while holding the SHIFT key depressed then move the cursor as before To move the cursors to another trace press the up or down arrow keys 290 ATS 2 User s Manual The Graph Options Menu Audio Precision A A VIEW WAYEFORM Amplitude vs Time erce lreeecoor Tere selme Joso os Conmen owsor euso FFT ChA Amplitude Left 1 166 V aik a soia tis ee AE Soia E1 ETC Ampitude Rit EAS V 1TA Y Figure 227 Graph Cursors on a selected trace with graph legend highlighted One or both cursors can be deselected entirely or the two cursors can be assigned to different traces In the Legend box there are two columns labeled Cursor 1 and Cursor 2 The data in these columns are the Y val ues for that particular cursor position Two of the cells in the Cursor col umns also have an asterisk leading the numeric values This asterisk indicates the cursor assignment To reassign one cursor to a different trace first click the Cursor 1 or Cursor 2 column header which will change to read Select The entire column will be highlighted Then in that column click the cursor cell in the row which corresponds to the trace where you would like to move the cursor To unassign cursors select a cursor column as in the previous paragraph and click on the cell displaying the cursor selected asterisk The cu
368. n to your printer Click Print to File A file browser dialog box will open Figure 264 Print to File Browser Swena HG c File name ii Cancel The type of file which will be created depends on the printer driver soft ware which you have chosen For example if you have a Postscript laser printer selected in your Print Setup and then click Print to File the file you create will be a Postscript file Save as type MA Ze Postscript and HPGL files can be saved and later directly outputted to a printer Additionally many word processing and graphics programs will im port HPGL and Postscript print files A Postscript file can also be converted to an Adobe Acrobat PDF file us ing the Adobe utility Acrobat Distiller ATS 2 User s Manual 333 Chapter 20 Printing and Exporting Exporting a Graph Exporting a Graph An ATS graph can be exported as a vector graphics file which can then be imported by a graphics software draw program for editing and print ing ATS will export vector graphics files in the Enhanced Metafile emf format Figure 265 Export Graph Browser saven far Aa e File name emf Save as type Enhanced Metafile ert Cancel Ze From the Menu bar choose File gt Export gt Graphics to export a graph as a metafile Copying a Graph to the Clipboard To copy an ATS graph to the Windows Clipboard use the command Edit gt Copy Panel to Clipboard This c
369. n track tuned filter see bandpass bandreject filter 150 Digital amplitude units 376 Digital data units 378 Digital full scale 376 Digital Generator frequency units 101 overview 99 panel LL 100 Digital I O panel OVOIV OW 51 ATS 2 User s Manual index Digital Input connection 39 front panel connectors 32 selecting dual connector mode 62 selecting the format 61 selecting the inoutimpedance 62 Digital Input Output panel see Digital I O panel 51 Digital Interface Analyzer OVOIV OW 187 Digital interface serial formats electrical vs data characteristics 39 Digital interface signal input coding indicator 68 input confidence indicator 68 input configuration 60 input data bit indicators 67 input error indicators 68 input frequency scaling 65 input jitter measurement DIO 69 input lock indicator 68 input parity bit indicator 68 input peak monitors 66 input resolution 64 input sample rate see ISR input validity bitindicator 69 input voltage 63 output configuration 52 output frequency scaling 57 output polarity 57 output resolution 55 outp
370. n when loaded To open the test macro or program click the button on the Quick Launch toolbar In a default installation the Quick Launch sample files are installed under Program Files Audio Precision ATS 2 Quick Launch ATS Add ins An Add In is a small software package that adds a specific set of features to ATS Add Ins can be downloaded and installed from the Audio Preci sion Web site ATS 2 User s Manual Working with Files and ATS Chapter 2 The ATS Control Software An activated Add In appears as an additional menu item in the appropri ate ATS menu If you have an Internet connection you can browse the available Add Ins using the Help menu Help gt Audio Precision Web gt Add Ins or go to our Web site at ap com Working with Files and ATS Part of the power of the ATS control software is its capability to create store load and run files which contain test setup and measurement data in formation similar to the way a word processor or spreadsheet application uses document template or script files Test Files The key document created by the ATS software is the test although ATS uses other file types as well The measurement settings and readings control software settings associated file links and if you ve actually used the test on a DUT the measurement data are all saved in the test file These files can be opened re used modified and re saved as you wish The filename extension for test
371. na e Scale Frequency OUTDUE o es e ard ews Sa o Script see macro SDI see serial digital interface signal Serial digital interface signal Setting limits see limits Settling algorithM amp os es wee sad TOO oros see sweep settling tolerance Shaped dither see dither Shortcuts keyboard 437 Index Signal analysis overview Analyzer instruments audio signal analysis digital signal analysis serial digital interface analysis Sweeps andGraphs Signal inputs and outputs main overview Sine Dual waveforms Sine Stereo waveforms Sine Var Phase waveforms Sine Offset waveform Sinewave Analog Generator Digital Generator Single pointsweeps external sa aw amp a oe 4 Smooth Compute algorithm SMPTE IMD measurements see IMD measurements SMPTE IMD waveforms Software Add In source 1 in an external sweep scales IOG O IMA 020 500 0 aaa start and STOD s sq ar aa SOUCO 2 aerosoles Source monitor outputs Source Reference Input Source Regulation parameter SPDIF see S PDIF Speaker monitoring Speaker Headphone panel see Headphone Speaker panel Spectrum Analyzer commands Spectrum FFT display processing Spectrum Waveform toggle button Specturm Analyzer
372. nalog and Digital inputs the converter and sample rate selections are on the ATS Analog Input panel m If the Digital Analyzer is being mapped the translator selects Analog or Digital Input and the converter and sample rate based on the Cascade Digital Analyzer s Input setting control m Test Trans If the HiBW converter was selected for Cascade but the Performance Option is not installed in ATS 2 the default HiRes converter will be substituted Macro Trans If the HiBW converter was selected for Cascade it is mapped assuming that the Performance Option hardware is available If the option is not installed this will cause an error at run time m If a Digital Input mode was selected for Cascade the ATS Analyzer panel is set to Digital and the Analog Input Panel is set to HiRes 65536 ATS 2 User s Manual 427 Appendix F Test and Macro Translators Mapping exceptions and substitutions m If the Analog Analyzer is being mapped Analog will be selected on the ATS Analyzer and the Analog Input panel is set to HiRes 65536 ATS 2 has bandwidth limitations that do not exist in System One and System Two Band limited readings in ATS 2 may differ from System One or System Two readings No notice of the possiblility of such differences will be written to the log file m The analog input source selections on the Digital Analyzer are quite different between System Two and ATS 2 and not every case can
373. nalyzer the Channel A bandpass filter is steered to 2 kHz a measurement is made and the per centage of the Channel B Level meter reading this crosstalk measurement represents is computed and displayed in the Channel A Function meter dis play Likewise the Audio Analyzer Channel B bandpass filter is steered to 1 kHz a measurement is made and the percentage of the Channel A Level meter reading this crosstalk measurement represents is computed and displayed in the Channel B Function meter display Crosstalk is a ratio expressed as Level of F inA Crosstalk from Binto A FB When only one channel is driven a Crosstalk percentage reading for the driven channel will display absurdly high percentages since the denom inator of the fraction the un driven channel level is very close to zero Also since the source of the denominator is a Level meter which is unfil tered spurious frequencies may produce erroneous Crosstalk ratios In this case a pre analyzer filter may be useful Crosstalk may be expressed in dB or X Y units The Channel A Function meter shows the percentage of the signal crossed from B into A and the Channel B Function meter shows the percentage of the signal crossed from A into B Since the bandpass filter will reject most wide band noise the Crosstalk function provides more accurate measurements of low ampli tude signals in the presence of noise The filter must be tuned to the fre quency of the signal on t
374. ncy required to obtain that constant modulation value This curve is essentially a modulation sensitivity test Plotting the generator amplitude using normal units will result in a curve that is inverted from the actual preemphasis curve shape of the transmitter Use dBrInv relative decibels inverted for the generator units to invert the trace and produce a preemphasis curve ATS 2 User s Manual 359 Chapter 24 Regulation 360 ATS 2 User s Manual Configuration and the Utilities Menu The Utilities menu offers access to the system Configuration panel and also to several utility functions and programs We ll look first at the Configu ration panel Go from the Main Menu to Utilities gt Configuration Figure 278 The ATS Utilities Menu The Configuration panel The Configuration panel allows you to set your preferences for ATS be havior There are three tabbed pages on the Configuration panel ATS 2 User s Manual 361 Chapter 25 Configuration and the Utilities Menu The Configuration panel General Figure 279 The General Configuration tab General Log Graph T Load LAST ATS2 on startup I Save LAST ATS2 on exit T Keep all readings active during real time sweeps M Display data in graph on test open IY Reprocess FFT data on zoom T Do not load panels on Open Test Set Sample Rate when loading generator waveforms Company Mame audi Precision Cancel Help The General configuration page enabl
375. nd to access the different Digi tal Interface Analyzer views INTERYU DIGITAL INTERFACE TESTS EE eee SEVA j AES ALA a AEE Alp DIGITAL CONNECTIONS C SPDIF OUTPUT INPUT Type Sample Rate OSR 5 pp Type of 16 No Term 4 851 Vpp XLA Bal 48000 fy Bits Gen Mon pees 48000 0 Hz VERTICAL AxIS Sweep Data 7 thru 6 HORIZONTAL JITTER HISTOGRAM AMPLITUDE UPPER EYE Sweep Probability LOWER EYE Source 1 AMPLITUDE Sa is eaal not valid nat valid FREQUENCY TOS ope not walid JITTER not valid ERAS not vali not valid More DIO Tests Settings About Interface Tests Exit Figure 161 InterVuMenu atsb menu screen ATS 2 User s Manual 201 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer panel settings InterVuMenu atsb provides a graphical user interface shown above that loads a selection of sample tests that can be viewed as an introduction to the Digital Interface Analyzer or that can be modified and saved for your own interface measurements Digital Interface Analyzer panel settings Figure 162 The Digital Interface Analyzer ERSZ joik panel INTERYU Digital Interface Analy Interpolate Stable Bits Blackman Harris Analog Gen e Ronin e Esama 1 00000 kHz Wave Display processing Time Domain view only Figure 163 Digital Interface Analyzer panel Wave Display selections Interpolate Display 5 amples Pea
376. need How close together must they be Would my sweep be more useful on a linear or a logarithmic scale With this type of information at hand it will be easy to set up the Sweep panel for your test We ll start by looking at the ATS Sweep panel and its controls and displays ATS 2 User s Manual 257 Chapter 15 Sweeps and Sweep Settling The Sweep Panel The Sweep Panel A Sweep le Data 1 AnalyzerAmpltudeA a Data g None O Top 16 00 Y ef Autoscale Data None Ej Bottom 1 000 my 2 Loa Lin Data g None s al fate limes Dago El Data a None E ints ad ie 87 irate ints E Top z JS toeea Pre Sweep Delay 200 0 msec Bottom Log Lin ie MY T Create Table Divs T uto mite O x y Data2 On X M Create Graph Source 1 Analog Generator Frequency El Source 2 None E Stark 20 0000 kHz Stark Stop 20 0000 Hz y DJ Ja Auta si F Sheps ETS STEHE Multiply 794 328m Table Sweep Repeat Stereo Sweep l rer Timeout per step 14 000 Figure 214 The ATS 2 Sweep Panel expanded display the Menu bar or by clicking the Sweep button on the toolbar you can also launch the Sweep panel by selecting Sweep gt Show Panel from the Menu bar or by using the keyboard combination CTRL S y The ATS Sweep panel is available by selecting Panels gt Sweep from Normally the Sweep panel is used to control a Generator and to collect readings from the Analyzer to produce sweeps for graphing It a
377. nel See Chapter 7 This button opens the Sync Ref Input panel See Chapter 22 This button opens the Status Bits panel See Chapter 7 This button opens the Headphone Speaker panel See Chapter 21 This button opens the DCX panel See Chapter This button opens the Switcher panel See Chapter This button opens the Auxiliary Digital I O panel See Chapter 22 MERE E a A amara This button opens the Trigger panel See Chapter 22 1 1 5 IE Erei 22 ATS 2 User s Manual The ATS Menus Chapter 2 The ATS Control Software This button opens the Sweep panel See Chapter 15 This button opens the Settling panel See Chapter 15 This button opens the Graph panel See Chapter 16 This button opens the Data Editor panel See Chapter 18 This button opens a new Bar Graph panel See Chapter 17 This button opens the Macro Editor panel See Chapter 23 Qu O a e E The Macro Toolbar Macro es Ale UN Se Ge The Macro toolbar offers 9 one click operations for running and editing an AP Basic Macro See Chapter 23 Automating Tests for explanations of functions initiated by Macro toolbar buttons The Learn Mode Toolbar ae Learn mode logs all your ATS operations as you perform them building a script for automation purposes The Learn Mode toolbar gives you the ability to turn the script recording function on and off with a click of the mouse See Chapter 23 Automating Tests for explanations of Learn Mode toolbar
378. nels gt Auxiliary Control I O or the Auxiliary Control I O button on the Panels toolbar ATS 2 User s Manual Auxiliary Control Output and Input Chapter 22 Sync Ref Trigger and Aux Figure 273 The Auxiliary Control I O panel Output ojoo pi B EE d lalalala Input E 1diPo fa fififalo You can set the output directly from the panel by clicking on the binary switches The value of your setting is displayed in the field to the right in decimal hexadecimal or octal units The Auxiliary Control I O is a sweepable setting The input states are read and displayed below the output settings This reading is updated at a rate of 4 s CO FA Table 3 Auxiliary Control port connector pin assignments output and input The pin connections of these ports are shown in the table above The current drive capability of each bit line is 5 mA the output impedance is 390 Q ATS 2 User s Manual 349 Chapter 22 Sync Ref Trigger and Aux Auxiliary Control Output and Input 350 ATS 2 User s Manual Automating Tests Introduction Almost every ATS command and panel setting has a corresponding OLE Object Linking and Embedding command OLE automation can be used by programming languages such as Microsoft Visual Basic to control and automate software functions in independent applications such as ATS AP Basic is a programming language specifically designed for ATS 2 and included with the ATS software If you are
379. ng an Analog Generator Waveform 84 This selection produces two independent sinewaves which are summed to create a complex waveform This complex waveform is sent to both channel outputs The Frequency and Frequency 2 fields permit each component sinewave frequency to be set independently The Dual Ampl Ratio field enables you to set the ratio by which the secondary Frequency 2 sinewave component amplitude will be attenuated with respect to the am plitude of the primary Frequency sinewave component In Sine Dual the amplitude setting determines the sum of the ampli tudes of the two components A 1 V amplitude setting with a 25 ratio produces a waveform which is the sum of a 800 mV sinewave and a 200 mV sinewave The Sine Dual signal is particularly useful as a calibration signal for harmonic distortion analyzers where the Frequency signal at reference amplitude represents the fundamental signal The secondary Frequency 2 sinewave can be set to any desired harmonic of the primary Fre quency fundamental sinewave at an amplitude to represent any de sired distortion level For example setting the primary Frequency at 1 kHz and the secondary Frequency 2 at 3 kHz with a Dual Amp ratio of 40 0 dB 1 produces a 1 kHz signal with third harmonic distortion of 1 0 Wfm Sine Shaped Burst Figure 52 An example ofa MN shaped burst A tone burst is an audio signal usually a sinewave that is keyed on and off
380. ng errors in the first 23 bytes bytes 0 22 If the CRC Enable box is checked ATS automati cally computes a CRC byte based on the data in bytes 0 22 and transmits that byte as status byte 23 This is normal operation If the CRC Enable box is not checked the CRC is not computed and you may enter arbitrary values into byte 23 of the Hex Transmit field to test the error detection capability of the receiver in the DUT Receive Status Bits Figure 39 Display of Received Status Bits Receive A Receive B Channel A showing Mode HEEE Mode METE Professional Format Audio Mode TES Audio Mode EEN and Channel B Emphazis Mone Copyright Mon Copyright poa adi Freg Mode Locked Erniphasis No pre emph Sample Freq Nat Indicated Channel Mode 2 Channel Channel Mode Mat Indicated Categor Code General User Bits Mone Source Mum Don t care Auiliary Bits 20 bit not define Channel Pr Dont care Audio Word Ler Mat indicated Sample Freg 441 kHz Ref Signal Mat a ref signal Clock Accuracy level Origin D Dest PERTE Local Address 2118528 Time of dar y Reliability Flags 0 5 14 17 On unreliable 6 1 3018 21 CRE Valid The right side of the Status Bits panel displays the conditions read in the incoming interface data This display is updated approximately four times per second If there are no incoming data the panel display defaults to the consumer format fields The professional format Reliabil
381. ngth in samples assuming a 48 kHz sample rate and the use of Freq Corrected Multiply the values shown by 0 5 for a 96 kHz sample rate by 1 088 for a 44 1 kHz sample rate and by 1 50 fora 32 kHz sample rate If a Trigger Delay is set the amount of the delay must be added to the minimum multitone signal duration ATS 2 User s Manual Acquired Waveform Files Chapter 13 The Multitone Audio Analyzer Invalid Multitone Readings When data are not available for graphing or tabular display for the se lected combination of Multitone Analyzer display mode and Sweep Source instrument the reading will be invalid The following chart lists the read ings available for each combination Available Multitone Readings by Measurement and Sweep Type Normal Sweep Table Sweep Amplitude Phase Amplitude Phase Peak picked bin Nearest bin Nearest bin Same as magnitudes phase magnitude Normal Sweep Interpolated rss Interpolated Same as Same as Response Normal Sweep Normal Sweep rss from previous invalid Same as Same as sweep freq Normal Sweep Normal Sweep rss from previous Invalid Same as Same as sweep freq Normal Sweep Normal Sweep Masking Interpolated invalid Same as Same as Curve masking curve Normal Sweep Normal Sweep Crosstalk Interpolated rss Invalid Nearest rss Same as magnitude magnitude Normal Sweep Table 2 Available Multitone Readings by Measurement Amplitude and Phase results and by Normal Sweep or Table Sweep op
382. nnel B The lenath is 2048 samples len 2048 Samp GUM ten samp rate 40000 eli Asta Seno av Lease ou ILO seas temes ei 2 ia a len slo ice meme MO Mene tomas silo mese 20000 1 da Se ela la This generates a file sin_noise ags The actual frequency of the sinewave is 996 094 Hz This is a frequency that is synchronous with the sample rate and the waveform length That is when the waveform is repeated there are no discontinuities ATS 2 User s Manual 413 Appendix E AP Waveform File Support MATLAB support 414 ap_read_wave Syntax ap bead wave filename system E Wave luis ys cen apurecdiwave ilenane aprte men elarel Description ap read wave imports an Audio Precision waveform file into a MATLAB structure array One structure is created for each waveform in the file Files with extensions aam mono acquired waveform aas stereo ac quired waveform agm mono generator waveform and ags stereo gen erator waveform are supported The file is closed on exit When reading an acquired file aam or aas the case insensitive pa rameter system must be supplied to scale the results correctly Choices for system are m ATS2 for ATS 2 m S1 for System One m S2 for System Two m S2C for System Two Cascade If the wrong system is supplied the results will be unpredictable When reading a generator file agm or ags system is not required Each structure consists of a sampl
383. nt of either analog input signal by checking the DC checkbox for either channel m If the checkbox is checked DC coupling is enabled for that channel m If the checkbox is unchecked a capacitor is inserted into the circuit and the DC component is blocked for that channel Converter and Sample Rate Selection All signal analysis within ATS 2 is performed in the digital domain and analog input signals must be converted using analog to digital converters ADCs In ATS 2 these are normally 24 bit high resolution ADCs You can choose one of two sampling rate references for the high resolution ADCs from the Converter amp Sample Rate drop down list HiRes 65536 Hz This is the best choice for most audio testing The high resolution converters offer better noise and distortion characteristics than the optional high bandwidth converters and when the sampling rate is set to 65 536 Hz the high frequency response of the analog inputs extends to 30 kHz a HiRes OSR This setting uses the high resolution ADCs but the value of the sampling rate is taken from the Output Sampling Rate OSR setting on the Digital Input Output DIO panel Some tests such as multitone analysis require that the digital signal applied to the DSP be synchronous with the OSR and this selection provides that synchronization At the maximum OSR of 108 kHz the high frequency response of the analog inputs extends to 50 kHz See Chapter 7 The Digital I O Panel ATS 2
384. ntered in the Amplitude field corrected by the value at that fre quency of the correction factor in the attached EQ file When Sine EQ is selected the values in the Amplitude field are displayed in blue rather than black To set the output amplitude you can enter a value in either the Ampli tude field or the Post EQ field and the value in the other field will be properly adjusted according to the correction factor The Analog Generator will not permit an output amplitude entry greater than 16 Vrms 22 62 Vp when configured for a balanced output or 8 Vrms 11 31 Vp when configured for an unbalanced output If the value of the normal pre EQ Amplitude field as modified by the equalization file would attempt to produce an amplitude greater than these maximum values an error message is displayed If a frequency value outside the frequency range span of the EQ file is entered on the generator panel or occurs during a sweep the Post EQ am plitude will go to O V ATS 2 User s Manual 87 Chapter 8 The Analog Generator Choosing an Analog Generator Waveform 88 Specifying the EQ Curve The EQ curve is specified by an AP data file usually an EQ file with the extension atsq which lists frequencies in Column 1 and the corre sponding amplitude changes in Column 2 or another column of your choice Equalization Curve Analog Generator Frequency xi Column 2 Analyzer Level 4 Edit OK Cancel Look in A
385. nterface Analyzer is an optional DSP instrument selec tion on the Analyzer panel It is named Intervu on instrument browser lists and in AP Basic macro references The Digital Interface Analyzer brings to ATS 2 the capability for in depth analysis of the serial digital interface signal The Digital Interface Analyzer is included with the ATS 2 Performance Upgrade Option package Check the serial number option label on the rear of the ATS 2 chassis to verify the presence of the Performance Upgrade Option If this option is not installed the Digital Interface Analyzer will not be available on the Analyzer panel ATS 2 Digital Interface Analyzer Analysis Tools The AES3 IEC60958 serial digital interface signal which carries the em bedded audio can be analyzed as a signal in its own right The ATS 2 digital input is connected to a receiver circuit that recovers the timing information the audio data and the non audio data from the se rial digital interface signal Basic information about the interface signal is re ported to the DIO panel which displays real time voltage and jitter amplitude measurements and flags up to four defined errors with panel in dicators Also the jitter signal appears as an input selection to the Spec trum Analyzer for further analysis For more information see Chapter 7 regarding interface measurements on the DIO panel and Chapter 11 for jit ter analysis with the Spectrum Analyzer ATS 2 User s Manua
386. ntical format the extensions are different as an administrative aid to help you and the ATS software deter mine the intended purpose of a particular data file A consequence of this is that you can use an EQ file atsq for a Table Sweep or a Data file atsa for setting limits ATS 2 User s Manual Setting Limits Chapter 18 Editing Data and Setting Limits This is particularly useful as it enables you to save all your data includ ing Sweep data EQ and Limit data in one file You can then attach the file as a Sweep Table or Limit or EQ file and select the appropriate data col umn from the list within the file browser AP data files are binary files and it is not possible to edit the files with out using the Data Editor or the Attached File Editor However it is possi ble to export the current data in memory as an ASCII text file for use in a spreadsheet or text editor program The ASCII file contains AP data file header information and the data in a comma delimited format The exten sion for the ASCII file is atsx You can open the ASCII file in Microsoft Excel for example edit the data and save the file and then re import the file into ATS and save it once more in one of the native AP data file formats When editing the ASCII version of an AP data file in an external pro gram you must keep the correct column row relationships and maintain or insert a correct file header at the top of your data Here is an example of th
387. ntinuous sweeps or glide sweeps Since the signal is gliding continuously from one value to another ina glide sweep it will never stabilize and settle as it will in a step sweep which pauses at each step for some period of time To acquire these continuously changing values ATS s sweep settling features must be disabled See Sweep Settling on page 278 On the Settling panel set the Analyzer Frequency settling Algorithm to None and Delay to 0 00 Also check your Min Lvl settings The default meter assigned to make the Min Lvl reading is Analyzer Level A but a browser can offer you a selection of other sources Be sure the meter that you have selected is the ATS 2 User s Manual Time Sweeps Chapter 15 Sweeps and Sweep Settling appropriate meter for your test that you have considered the effect of any filters you may have attached to the meter and that the Min Lvl threshold setting is correct External Stereo Sweep External sweeps can also be configured as stereo sweeps by clicking the Stereo Sweep checkbox on the Sweep panel ATS will automatically set the Data 3 and Data 4 if necessary settings to match the Data 1 and Data 2 settings for stereo pairs See Stereo Sweeps on page 267 fora full discussion Since ATS is entirely dependent upon the External signal in an External sweep the automatic switching for the Stereo sweep crosstalk feature page 267 for ordinary sweeps is not available for external sweeps External
388. ntly with Channel A settings and readings to the left of the panel and Channel B to the right Source Select the analog input source for each channel from the drop down list The choices are XLR Bal a This selection attaches the input channel to the balanced XLR input connection GenMon ATS 2 User s Manual 45 Chapter 6 The Analog Input Panel Peak Monitors m BNC Unbal This selection attaches the input channel to the unbalanced BNC input connection GenMon This selects the generator monitor path which bypasses the external analog inputs and instead attaches the input channel to the Analog Generator output via an internal connection See Chapter 4 Signal Inputs and Outputs for more details concern ing the physical and electrical characteristics of the analog input connec tions Input Termination Option Figure Tal if Analog Input The ATS Analog Input panel shown with Channel A Channel B the 600Z impedance option xLA Ba y Source xLA Ba MAMA gt ek Mon a AV ees af ooo FT oc DC I E Impedance 100k OOk aa AE Rate HiResca655 36 gt In the standard or European impedance configurations the input load at each of the analog inputs is fixed at a high impedance greater than 100 kQ If you have ordered your ATS 2 with the 600 Q impedance option ATS2 600Z an additional field will be displayed on the Analog Input panel as shown in Figure 13 With this option insta
389. ntrolled by the Phase B A field A positive value entered in the Phase B A field will cause the Channel B output to lead the Channel A output A negative value entered in the Phase B A field will cause the Channel B output to lag the Channel A out put See the illustration below 82 ATS 2 User s Manual Choosing an Analog Generator Waveform Chapter 8 The Analog Generator Audio Precision Figure 49 Sine Var Phase triggered on Channel A the larger waveform 90 00 deg has been entered in Phase B A field causing B the smaller waveform to lag A Wfm Sine Stereo Figure 50 Analog Generator Sine Stereo L Analog Generator Miel wfm Sine Stereo Frequency 1 00000 kHz gt dl air Frequency 2 2 00000 kHz Lh B This waveform selection produces independent sinewaves on Channel A and Channel B The Frequency field sets the frequency of the Channel A signal and the Frequency 2 field sets the frequency of the Channel B signal Their amplitudes are independently set by the two Amplitude fields unless the Track A box is checked in which case the amplitudes are equal and controlled by the Channel A Amplitude field Wfm Sine Dual Figure 51 Analog Generator Sine Dual Analog Generator wim Sine Dual Frequency 1 00000 kHz IT ChA E Frequency 2 2 00000 kHz F t ChE Dual Amp Ratio 250 0 ey ATS 2 User s Manual 83 Chapter 8 The Analog Generator Choosi
390. nual Digital Amplitude Units Appendix A Units of Measurement 20 dBFS dBFS is probably the most common unit of measurement used for digital audio amplitudes O dB FS is the full scale reference MAXIMUM DIGITAL CODE rms reading 3 01 dB FS y rms reading 0dB FS MINIMUM DIGITAL CODE Figure 286 The squarewave has a lower crest factor than the sinewave Since dBFS is defined in rms terms a squarewave with the same peak value as a 0 dBFS sinewave will have a value of 3 01 dBFS bits Bits is another way of describing the dynamic range of a digital converter by converting a measured dynamic range value to the equiva lent number of bits the digital word length that a signal would theoreti cally require to attain that dynamic range The calculations take into account the effect of quantizing noise in the LSB by the 1 76 dB offset For example the theoretical dynamic range of a 16 bit system can be calculated to be about 98 1 dB using this formula Dynamic Range 6 02 number of bits 1 76 dB Conversely a dynamic range of 98 1 dB can be expressed as 16 bits Levels can also be expressed in this notation The ATS bits unit is com puted from dBFS using the following relationship where dB is the level to be expressed relative to full scale l E zn bits 6 02 For example a signal at 0 0001 FFS or 80 dBFS can also be stated as 12 99 bits A consequence of the 1 76 dB of
391. nuously measure the amplitude of the third harmonic only Clicking the 2 8 and 10 in the upper row and the 7 and 13 in the lower row of a meter causes a continuous display of the rms sum of the 2nd 7th 8th 10th and 13th harmonics of the signal Checking the boxes at the left end of both rows causes a THD total harmonic distortion with out noise measurement that includes the effects of the 2nd through the 15th harmonics Distortion Product Bandwidth Limitations Note that only those harmonic components within the measurement bandwidth of the analyzer can be measured even if all the harmonic or ders are selected For example assume that an analog signal is being measured using the HiKes 65536 converter selected on the Analog Input panel which es tablishes a bandwidth to about 30 kHz If the fundamental frequency is 9 kHz only the 2nd 18 kHz and 3rd 27 kHz harmonics fall within the measurement bandwidth Selecting any harmonic orders above the 3rd will have no effect on the measurement When the fundamental is below about 2 kHz all harmonics up to and in cluding the 15th will be measured When the stimulus signal frequency is swept during a test higher order harmonics will be included while the stim ulus frequency is low but excluded by the fixed bandwidth when the stimu lus frequency is high ATS 2 User s Manual 249 Chapter 14 The Harmonic Distortion Analyzer Harmonic Distortion Product Amplitude 250 With analo
392. o be accessed as context sensitive help pushing F1 while the cursor is within command string in the AP Basic macro editor m AP Basic Language help is a listing of the general non instrument specific commands available in AP Basic m AP Basic Editor help provides topics about the use of the AP Basic macro editor m About ATS provides information about the specific release of ATS control software m Release Notes is a shortcut to the Readme file 18 ATS 2 User s Manual The ATS Menus Chapter 2 The ATS Control Software Access to the Audio Precision Web site Audio Precision Web Add Ins Home Learning Center Samples The last line on the Help menu m Audio Precision Web opens a submenu that lists the Web links currently provided to ATS The list will vary from no links to many depending upon the ATS installation and version and whether or not new links have been added or deleted through visits to the Audio Precision Web site at ap com or other file main tenance You will typically have Web links to m Add Ins additional software features for ATS downloadable from the Audio Precision Web site See page 24 for more information about Add Ins m Home the Audio Precision home page m Learning Center the Tech Support Learning Center area at Audio Precision m Samples the Tech Support Samples area at Audio Precision The status Bar For Help press Fl A The Status bar runs across the bott
393. o be appended ATS 2 User s Manual Stereo Sweeps Chapter 15 Sweeps and Sweep Settling The data currently in memory and the file to be appended must be com patible in these ways m they must have compatible Source 1 selections for example both set to frequency or both to amplitude m they must both have the same structure of Data 1 and Data 2 selections for example a data file with data plotted at both Data 1 and Data 2 can not be appended to current data in memory which has Data 2 set to None m they must both have compatible measurement domains for example a measurement of distortion shown in percent units which expresses a ratio may not be appended to a measurement of level in amplitude units which does not express a ratio However distortion shown in absolute units such as volts or dBu can be appended to amplitude data Data appended from a file will be graphed in the same color used in the original test or data file Both the original and the appended data can be viewed in the Data Editor Stereo Sweeps ATS has the ability to sweep two channels of a device simultaneously with the Stereo sweep function Although you could manually set up two sweep Data functions and get the same results using the Stereo sweep function brings some additional advantages m Automatic selection and setup of opposite channel data settings including Limit file selection If you have entered a channel of only one reading instr
394. o command to reference the copied file For example if the imported procedure references a file named MyLimits adl the Macro Translator will copy the file to MyLimits atsl and will change the reference within the translated macro to the new file name Unavailable Features Commands which reference features that are not available in ATS 2 are flagged If there is a reasonable substitution it will be made if not the command will be commented out Reporting Macro Translation Exceptions Like the Test Translator the Macro Translator reports activity to the Log File However most macro translation notes appear as comments within each translated macro file When the translator detects situations that re ATS 2 User s Manual 425 Appendix F Test and Macro Translators Mapping exceptions and substitutions 426 quire user attention a comment will be placed in the code preceding the line or lines of code that need to be examined The comments inserted by the translator all begin with two asterisks so that they can be easily found When multiple subsequent lines all have the same comment the comment is placed only once at the beginning of the code block The translator also puts comments at the beginning of each macro to in dicate that it was translated from an APWIN procedure and to log the date of the translation These comments within the AP Basic script can help you to understand the translation process and deb
395. o that the software will be informed of the ATS 2 hardware options that are installed in your system and will configure the imported test accordingly How the Test Translator Makes Decisions The Test Translator will correctly convert the vast majority of control set tings and readings from APWIN tests to ATS tests APWIN controls that are the same as ATS controls are mapped to those controls APWIN controls that have similar counterparts in ATS are mapped to the best match or to a default APWIN controls that have no counterpart in ATS are discarded Many tests will function as designed with no additional input and many others will only require minor changes However the great differences in system architecture mean that some controls settings or readings simply will not translate Some testing strategies may require a new approach that makes the best use of the features on ATS 2 We recommend that you have a solid understanding of the architecture and features of both ATS 2 and the System in which the original test was created and that you review the purpose and the approach of each test candidate for translation When the translation is completed carefully check the converted test to be sure the settings readings and operation are what you expected It may be valuable to compare the results produced by the test on its original instrument and on ATS 2 Mapping Two Analyzers into One Analyzer System Two Cascade has dual analyzers on
396. o within the tolerance set by applying the Spacing percentage to the Start value For example if Start is 20 Hz and Spacing is 5 a reading between 19 Hz and 21 Hz will start the sweep Or if Start is 1 V rms and Spacing is 10 an amplitude between 0 9 and 1 1 V rms will start the sweep This rule governs the normal behavior of external sweeps The other two Start On rules are Beyond the Start Setting The sweep starts on a settled reading that is above the Min Lvl value and exceeds the Start value in the sweep direction up or down as determined by the relative values of the Start and End settings No data is collected until the Sourcel meter reading passes or equals the Start value Any Settled Reading The sweep starts on a settled reading that is above the Min Lvl value without regard to the value in the Start field Sweep measurements are collected in the direction set by the Start and Stop field values In a sweep with Start at 20 Hz and Stop at 20 kHz a 1 kHz measurement will not accept the next value until 1 kHz Spacing is satisfied Under this rule the data collected can include values above or below the sweep araph limits set in Start and Stop Some Hints Internal sweeps and some external sweeps are called step sweeps be cause the independent variable is moved across the sweep range in dis crete steps Many external sweeps however move across their range in a continuous change of values These are called co
397. of FFT processing throughout this discussion Acquiring Data The first step in performing an FFT is to acquire signal data which con sists of recording a sample of the signal to a special area in ATS 2 memory called the acquisition buffer ATS 2 has a 256k sample acquisition buffer for each of the two audio channels You can specify the amount of memory to be used in an acquisition in steps from 800 samples to 256k samples or you can set ATS 2 to have the acquisition buffer length track the FFT record length which is discussed be low The duration of the signal acquired will depend upon the acquisition buffer length and the sample rate of the signal and can be calculated from this formula Aquisition Length Acquisition Duration a Sample Rate At a sample rate of 48 kHz a 256k acquisition will have a duration of 5 46 seconds The FFT Record The FFT record is the section of signal upon which the FFT processing is actually performed Its length in samples is called the record length or FFT length or transform length The record length must be smaller than or equal to the length of the acquisition FFT Bandwidth The bandwidth of the signal the sample rate the record length and the frequency resolution are all related As with any digital signal the bandwidth is limited by the sample rate in this relationship Sample Rate Bandwidth andwi 5 ATS 2 User s Manual FFT Bin Width Appendix C FFTs FFT Bin Wid
398. oles on or outside the unit circle on the z plane m Filters with a gain of zero are not allowed Such filters would result in all zero outputs m No coefficient may be greater than 2 0 or less than 2 0 A simple text file format is used for each user designed filter The file for mat is specified by the following rules m All lines starting with are comment lines m Blank lines that is lines consisting of zero or more spaces and tabs are ignored m The parameters for filters are specified in a line oriented fashion with one entity specified per line m Each line has three components a predefined keyword followed by a colon followed by the keyword dependent data Any white space surrounding these components is ignored Three keywords are defined info sample _ rate and biquad m The info keyword specifies a text string of printable ASCII characters to be displayed on the User Downloadable Filters panel when the Filter Info box is clicked The info comment must be fewer than 1024 characters in length Only the first info keyword found is used any others are ignored a A filter at a given sample rate is specified by the sample _rate keyword line followed by one or more biquad keyword lines m The sample_rate keyword is followed by a colon and a floating point number expressing the sample rate in hertz There is no limit on the number of sample rates ATS s built in filters are provided at these sample rates
399. ols is fixed you must verify that the maximum signal ampli tude never exceeds digital full scale Acquiring Transforming and Processing The Spectrum Analyzer instrument acquires transforms processes and displays data in distinct steps For a frequency domain spectrum view there are three steps ATS 2 User s Manual 157 Chapter 11 The Spectrum Analyzer Acquiring Transforming and Processing m acquiring the data m performing the FFT and m processing the results for graphing Often all these steps are performed in quick succession for each spec trum display At other times only the last step or two are performed on an acquisition or set of transform results already in memory For a time domain oscilloscope view there are only two steps m acquiring the data and m processing the results for graphing Three sets of commands control the Spectrum Analyzer processes a Sweep gt Start Go F9 These commands are all equivalent and perform all three steps a new acquisition is made the data is transformed and the results are processed for display m Sweep gt Transform w o Acquire F6 These two commands are equivalent and perform the two last steps the acquired data is transformed and the results are processed for display No new acquisition is made Sweep gt Reprocess Data Ctrl F6 These two commands are equivalent and perform the last step the results are processed for display No new acquisition
400. om of the workspace and shows the workspace page tabs and various status notes as ATS operates The Toolbars and ATS Icon Buttons ATS has 5 toolbars for quick access to panels and common functions The toolbars can float at any location you place them on the workspace or they can be docked or attached to the Menu bar Whether docked or floating the toolbars appear on every workspace page The toolbars display icon buttons which when clicked with the mouse perform the associated functions ATS 2 User s Manual 19 Chapter 2 The ATS Control Software The ATS Menus 2 DD g BEB a 20 The Standard Toolbar Standard E Heth aieh Y AO The Standard toolbar gives you quick access to ATS file printer and edit ing operations as well as Sweep Stop Start and FFT Time Frequency do main switching The buttons on the Standard toolbar are New Test resets the ATS control software to its defaults and initiates a new test Open Test presents you with a file browser window to select a previ ously saved test file ats2 for opening Save Test saves the current test as ats2 If the test has not been previ ously saved you will be presented with a browser window to choose a file name and location Save All saves not only the current test but any other files which are currently open such as data or macro files If any file has not been previ ously saved you will be presented with a browser window to choose
401. ommand can copy the graph to the clipboard as either a bitmap or as a metafile vector graphic image To make this choice you must first set your preference on the Graph tab in the ATS Configuration panel at Utilities gt Configuration which is discussed in Chapter 25 The images captured in this way can be viewed and saved using Microsoft Clipboard Viewer or the contents of the Clipboard can be pasted into word processing or graphics documents Copying a Window or Screen to the Clipboard Microsoft Windows provides keyboard shortcuts for copying the entire screen or a selected window to the Windows Clipboard as a bitmap image To copy the entire screen to the Clipboard press Print Scrn To copy the active window to the Clipboard press Alt Print Scrn Third party screen capture programs will enable you to copy other screen areas to the clipboard 334 ATS 2 User s Manual Copying a Window or Screen to the Clipboard Chapter 20 Printing and Exporting The bitmaps captured in this way can be viewed and saved using Microsoft Clipboard Viewer or the contents of the Clipboard can be pasted into word processing or graphics documents Bitmaps and Vector Graphics A bitmap graphics file is a bit by bit image of the graph displayed on the ATS graph panel The resolution of a bitmap is set at its creation and magnifying the image will reveal the individual pixels comprising the image Bitmap files can be edited with paint graphics softwa
402. on in ATS 2 77 Two Audio Signal GeneratorS 77 Signals for Analog Measurements 77 The Analog Generator Panel 78 Frequency Units 2 008484 79 Output On Off and Channel Selection 79 AUO On lt cece ee das EERE GRRE EEE 79 Amplitude Control and Units 02 80 Choosing an Analog Generator Waveform 81 Sine waveforms 02 00 2 ee eee 81 Wfm Sine NO0rMal 82 Wfm Sine Var Phase 82 Wfm Sine Stereo 2 202 2022 2 222208 83 Wfm SING Dual 82468 2 cake eewe ace Hwee td 83 Wfm Sine Shaped Burst 2 84 Wfm Sine EQ 20 20 2 a 87 SQUAFEWAVO ces eee ae ee eee teed SSR KSEE DEG 89 Wfm Square 2 2 2 2 2 00 0 eee 89 intermodulation Distortion IMD 2 89 Wfm IMD SMPTE DIN 4 1 89 Wfm IMD SMPTE DIN 1 1 90 Noise Waveform 200002 eae 90 iv ATS 2 User s Manual Arbitrary Waveforms 0 220500 08 91 Setting the DAC Sample Rate 91 Special WaveforMs 00505 ee ee 92 Wfm Special Polarity 2 00 93 Wfm Special Pass Thru 2 0080 93 Configuring the Analog Outputs 94 Analog Generator References 2 95 dBr Amplitud
403. on of the signal depends on the number of bits as signed to encode the signal value This is called the word length Word length or resolution also varies between different systems from perhaps 8 bits 256 discrete levels to as high as 24 bits 16 777 216 discrete levels Figure 287 A 3 kHz sinewave sampled at 48 kHz Value as a fraction of full scale 0 0 05 0 1 0 15 0 2 0 25 0 3 0 35 Time ms ATS 2 User s Manual 383 Appendix B The Digital Audio Signal The Serial Digital Interface Signal 384 The Serial Digital Interface Signal For reliable transmission and reception the PCM audio is encoded into an interface signal according to one of several international standards The interface signal adds channel identification synchronization data status in formation error correction and embeds the clock signal into the data stream BLOCK 192 FRAMES gt A Frames and FRAME gt lt lt FRAME gt Sub Frames SUBFRAME A SUBFRAME B SUBFRAME A SUBFRAME B AES3 Data Stream AES3 Preamble Patterns 3Ul 1Ul1Ul 3Ul 3Ul 2U1 1U 2UI 3Ul 3Ul 1Ul1Ul 3Ul 2U1 1Ul 2U1 atole I 2 Z B PREAMBLE Y W PREAMBLE X M PREAMBLE Y W PREAMBLE Unit Interval UI Time Reference Figure 288 The AES3 serial interface signal data pattern The AES3 and IEC60958 standards define the digital audio interface sig nal for both professional and consumer use There are several variati
404. on setting If the input signal being measured is using the Aux bits for another sig nal the Input Resolution must be set to 20 bits or fewer to strip off the Aux signal before measurement by one of the Analyzer instruments See Chapter 2 for an explanation of Aux bits in the digital audio word The input resolution is independent of the output resolution The input resolution may be swept as part of a test by selecting Dio as the instrument and Input Resolution at Source 1 or Source 2 on the Sweep panel M Law and A law Expansion See Figure 28 for reference The right field of the Resolution section allows selection of u Law or A law expansion This selection overrides the word width selected in the left Resolution field which is grayed out under these conditions Choose u Law or A law to enable the expansion or Bits to return to normal linear PCM resolutions See the sidebar on u Law and A law on page 56 for more information on these companding techniques ATS 2 User s Manual The DIO Input Section Chapter 7 The Digital I O Panel Deemphasis Figure 29 The DIO Deemphasis De emph asis OFF ll selections TE Scale Freg by AMi erent Peak Monitor 50 1 5us 12d8 Channel J17 Ode 317 20d8 A digital signal transmitted with preemphasis must be deemphasized on reception Since preemphasis is rarely used deemphasis is rarely needed See Preemphasis on page 56 To properly deemphasize a signal y
405. ons set out in the standards that are for the most part compatible The professional format is most often referred to as AES3 but is also called AES EBU or IEC60958 4 There are also other variations of the pro fessional format such as AES3id and SMPTE 276M These have the same data pattern but different electrical characteristics The consumer format is defined by IEC60958 3 and is also called S PDIF or EIAJ The consumer format differs from the professional in elec trical characteristics and in the interpretation of Status Bits The standards specify not only the pattern and encoding of the PCM au dio and other data but also the electrical and mechanical aspects of the in terface The ATS 2 balanced digital connectors conform to AES3 and the unbalanced connectors including the SYNC REF BNC on the rear panel satisfy AES3id All ATS 2 digital inputs and outputs will work with the data patterns of either the AES3 IEC60958 4 professional format or the IEC60958 3 consumer format Output format is selectable in software ATS 2 User s Manual The Serial Digital Interface Signal Appendix B The Digital Audio Signal We will use the AES3 professional standard as a model for this discus sion For the purposes here only the Status Bits interpretation is different for the consumer format Bi phase Mark Encoding To carry a consistent clock and provide for a robust transmission signal the interface data is processed by bi phase mark en
406. ons will be required to reduce the step size and bring the measurement into regulation Smaller steps will take longer to reach the approximate area near the Target value but may regulate the measurement more rapidly Iterations Iterations determines the maximum number of regulation steps which will be made for each measurement Regulation is considered successful if the target Value is attained within Tolerance without exceeding Iterations If Regulation is unsuccessful an Unregulated message is issued and an R is entered at the measurement on the Graph in the Data Editor and in the Log file if enabled For Normal Normal and Linear operations the Iterations field limits the maximum number of steps which the regulation algorithm will make in the search for the Target value Iterations should be large enough to permit successful regulation In Maximum and Minimum modes the Iterations field determines the number of times that the measured value passes through the target value before the algorithm halts A larger Iterations value will produce a more precise location of the target but will take longer to complete Generally broad peaks and dips can be located with a smaller Iterations value and sharper peaks or dips require a larger Iterations value Timeout per step The instrument readings used for regulation are first processed through the sweep Settling algorithm See page 278 for a discussion of Settling In some c
407. or measurements See the Specifica tions chapter in Getting Started with ATS 2 for graphs of the filter curves Several selections are provided in the weighting filter field None A Weighting CCIR Weighting F Weighting CCITT Weighting ATS 2 User s Manual 145 Chapter 10 The Audio Analyzer The Function Meters 146 C message Weighting HI 2 Harmonic Weighting and User Weighting Filter When any of these weighting filters is selected it affects the Function meter measurement paths of both channels The Level and Frequency meters are always unfiltered None applies no weighting filter a A Weighting processes the signal through a psophometric weighting filter meeting the ANSI A weighting specification n A weighting filter in combination with the THD N function is frequently used for dynamic range measurements of ADCs CCIR Weighting processes the signal with the weighting filter described in IEC468 It is normally used in one of two ways e When used with an rms detector this filter produces measurements in accordance with the Dolby Labs CCIR ARM method e When used with the Q Peak detector at a reading rate of 4 s this filter produces measurements satisfying the IEC468 standard The IEC468 standard specifies that the unity gain point in the test intersect the weighting curve at 1 kHz rather than the 2 kHz intersection specified for the Dolby Labs CCIR ARM method ATS automatically makes the 6
408. original input termination does not match the translated input termination Macro Trans gt 100 kQ will be mapped to gt 100 kQ and 300 Q and 600 Q will be mapped to 600 Q If the 600Z Option is not installed this re mapping will cause an error at run time Analyzer Settings m Any commands that references the Analog or Digital Analyzer in Cascade are mapped to reference the one Analyzer in ATS This can 428 ATS 2 User s Manual Mapping exceptions and substitutions Appendix F Test and Macro Translators be a problem for the user if both Analyzers are referenced in the code the result may be an incomprehensible mix of Analyzer commands m The System Two Cascade Analog Analyzer has only one analysis channel which is switched between channel A and channel B inputs The ATS 2 analyzer has two full analysis channels When translating these situations the translator software has no way of knowing which channel the Analyzer was set to and therefore doesn t know which ATS 2 Analyzer channel is referenced Test Trans APWIN Analog Analyzer references are mapped to ATS 2 Analyzer Channel A and a message is written to the log file Macro Trans APWIN Analog Analyzer references are mapped to ATS 2 Analyzer Channel A and flagged with a comment m Bandreject function is not supported in ATS It is substituted with THD N Ampl m CCIF DIM Wow amp Flutter and DFD measurement modes are not supported in
409. orresponding to the values in the EQ file selected Use the EQ Curve browser to attach the file Amplitude Enter the amplitude of the jitter in this field The units available are UI unit intervals dBUI decibels referred to 1 00 UI and s seconds typi cally ns or nanoseconds Jitter amplitudes are calibrated in terms of the peak value of a sinewave It may seem unusual to measure amplitude in units of time but jitter is a variation in time High levels of jitter produce large time displacements The unit interval is defined as the shortest nominal time interval in the coding scheme Since an AES3 signal has 64 bits per frame and the bi phase coding of the interface nominally doubles this rate there are 128 UI per AES3 frame The UI is useful because it scales with the interface data rate In the case of a 48 kHz sample rate and an AES3 frame as described above 1 1 UI ___ 163 ns 128 x 48000 s or with a 44 1 kHz sample rate se 17ns 128 x 44100 s Jitter amplitude may be swept as part of a test by selecting Dio as the in strument and Jitter Ampl at Source 1 or Source 2 on the Sweep panel Frequency Enter the frequency of the jitter sinewave in this field ATS 2 User s Manual 59 Chapter 7 The Digital I O Panel The DIO Input Section Jitter frequency may be swept as part of a test by selecting Dio as the in strument and Jitter Freq at Source 1 or Source 2 on the Sweep panel EQ Curve
410. ou must select deemphasis curves and gain 50 15 us Compact Disc at O dB or 12 dB or CCITT J17 at O dB or 20 dB that are complementary to the preemphasis conditions to provide overall unity gain and flat response The deemphasis and gain if any is implemented after the Channel A and Channel B Peak Monitors so the monitor readings will not be af fected as deemphasis is turned on and off Scale Freq by Figure 30 The DIO Scale Freq by Basia sige by Meas Input Rate R selections i Peak Monitor Output Aate EE heas Input Aate TE Status Bits 4 MINAS 010 Rate Ret ATS 2 must normalize the frequency of an incoming digital audio signal to a local sample rate before display whether the signal is to be displayed numerically or as a frequency component on an FFT graph Depending on the application there are several sources of sample rate which may be ap propriate for normalization ATS offers the capability to select one of four sample rate choices as a reference by which to scale the embedded frequency of the digital input sig nal The choices are Output Rate which is the rate set in the Sample Rate OSR field m Meas Input Rate which is the measured input sample rate ISR ATS 2 User s Manual 65 Chapter 7 The Digital I O Panel The DIO Input Section m Status Bits A which is the value of the sample frequency encoded into the received Channel A status bits m DIO Rate Ref which is a reference
411. ox open for further operations Compute and Close Keep the settings perform the computation and close the dialog box 318 ATS 2 User s Manual Compute Normalize Chapter 19 Performing Computations on Data It is possible to perform a Compute operation repeatedly or to perform several different compute operations in sequence You can do this manu ally by opening and configuring Compute dialog boxes and clicking the Compute button It is also possible to construct a series of computations which will be per formed on the data automatically at the end of the sweep Checking the Apply After Sweep checkbox in a Compute dialog box and then clicking Close will place that computation in a list which will be executed after the sweep is completed The order in which the computations are listed and ex ecuted is determined by the order in which you set and close the various compute functions This list can be viewed and edited in the Compute Sta tus dialog box page 326 Compute Normalize Compute Normalize allows you to move a trace up or down against the Y axis or normalize the data in relation to a new value For example you may have made a frequency response sweep at some arbitrary level but now wish to display the trace in relation to a O dBr A reference at the mid frequencies As another example you could make a sweep of a golden unit to get a reference response and then normalize the trace 3 dB above and then again 3
412. peak equivalent sinewave terms See Amplitude Control and Units on page 80 Figure 58 Analog Generator IMD Analog Generator Oo x Waveform Selections wfm IMD SMPTE DiN 41 7 SMFPTEDIN 4 1 High Freg 13 00000 k SMPTE DIN 1 1 IM Freg 80 0000 Hz at Wfm IMD SMPTE DIN 4 1 This selection produces a signal which is the linear combination of two sinewaves The first sinewave set in the IM Freq field is a lower fre quency tone that can be assigned any frequency in the range of 40 Hz to ATS 2 User s Manual 89 Chapter 8 The Analog Generator Choosing an Analog Generator Waveform 90 500 Hz The frequency of the second sinewave set in the High Freq field can be anywhere in the range from 2 kHz to 60 kHz The low frequency sinewave is linearly combined in 4 1 amplitude ratio with the high frequency sinewave Wfm IMD SMPTE DIN 1 1 This is the same as the Wfm IMD SMPTE DIN 4 1 selection except that the amplitude ratio of the low frequency sinewave to the high fre quency sinewave is 1 1 Noise Waveform ll x Figure 59 Analog Generator Noise Analog Generator Waveform Selection alten Noise The ATS 2 Analog Generator offers a DSP generated white noise signal The DSP generated noise is pseudo random and has a length of 2 or 1 048 576 samples The DAC sample rate is 131 072 kHz which means that the noise pattern repeats about every 8 seconds The noise has a zero
413. per illustration of Figure 188 are an example of this Masking Masking is a characteristic of human hearing A loud sound close in frequency to a quieter sound masks the quieter sound under these conditions we perceive only the louder sound For example faint noise or distortion products centered in a range around 7 kHz might be audi ble in an otherwise quiet signal but if a louder 7 kHz tone is added to the signal the noise will be masked The effects of masking vary with frequency and level Curves have been determined which quantify masking effects at different frequencies and levels for the average listener It is important to understand and measure masking effects to evalu ate under what conditions noise is audible in a dynamic signal The Multitone Audio Analyzer tests low bit rate perceptual coders with multitone signals by summing quantization noise and distortion and comparing it to an embedded psychoacoustic model of the frequency masking effect A composite curve is created which represents the total masking which would be in effect for the tones selected You can then append to this 224 ATS 2 User s Manual Multitone Measurements Chapter 13 The Multitone Audio Analyzer curve the original data in a spectrum or distortion view to produce a graph like the lower illustration in Figure 188 You can also save the masking curve data as a limit file and attach it to other tests Crosstalk CHANNEL A Figure
414. pical audio data the 1 UI and 2 UI spikes will be approximately equal indicating approximately equal numbers of one and two UI wide pulses logical ones and zeros in the em bedded audio data The 3 UI spike is significantly shorter lower probabil ity since pulses of that width occur only in the preamble Impaired rise and fall time and or interfering noise will cause each spike to become wider at correspondingly lower probability for any specific pulse width value The displayed time resolution of the pulse width histogram depends upon the span between the Source 1 Start and Stop values and the Source 1 Steps value Fa 4 0 2 A O a PL E UUs 0 02 ta 0 014 O Figure 158 Digital Interface Analyzer interface pulse width interface timing probability 48 kHz rate ATS 2 User s Manual Digital Interface Analyzer Histograms Chapter 12 The Digital Interface Analyzer As indicated in Figure 151 this view requires these Sweep settings Source 1 Intervu Time and m Data 1 Intervu Probability Source 1 range should be about 0 to 600 ns a Data 1 range of 0 01 to about 10 on a logarithmic scale is useful for this view On the Digital Interface Analyzer panel Wave Display can be set to any choice except Eye Pattern interface Bit Rate Histogram The interface bit rate histogram view displays the probability of occur rence of the various instantaneous frequency values of the interface wave form The Digital
415. pper and wi lower limit traces 7 Lh Un in i in 20 50 100 200 500 ik ha am A E ae x Limit Cyan Solid 4 Data 1 upperlimi Left Graph Legend Data Editor Linkage The display of information in the graph Legend is visually linked with the tabular sweep data display shown in the Data Editor For appended or 296 ATS 2 User s Manual Graph Legend nested sweeps this can help in identifying which line shown in the Data Editor is associated with a particular trace O Gen Freq 1 Gen Ampl aA 2 AninAmpl 420 0000 kHz 0 000 dBW 22 542 dBy 2 00000 kHz 0 000 doy 5 648 By le 200 000 Hz 0 000 dey 13 760 dey 20 0000 Hz 0 000 da 33 712 dB ls 20 0000 kHz 10 000 dBv 32 556 dBW 4 2 00000 kHz 10 000 dBv 4 375 dBv 200 000 Hz 40 000 dB 23 800 dBvV 43 742 dew 50 100 200 500 1k 2k Ak 10k 20k Hz axis Source 2 1 1 Cyan Solid 1 Analyzer Amplitude A Left 10 000 dBW Analog Ge 2 1 Green a Solid a1 sfanalyzer Amplitude A Lef 0 000 d8Y Analog Gene 3 1 Yellow Solid 41 Analyzer Amplitude A Left 10 000 dBV Analog Ge Figure 233 Graph Legend and Data Editor showing the linked relationship of the typefaces used in the two displays for a nested sweep This linkage in the displays identifies the correspondence between data and traces in two ways m Normal Type or Bold Type Alternate sets of traces in both the graph Legend and the Data Editor are displaye
416. pper limit flag Units of measurement 371 analog amplitude 372 DCX 127 2 80808 381 digital amplitude 376 digital data 378 frequency 379 function meter 140 phase 2 808 eee 380 o gc tae ae Pee eee eee ese ee 378 PelatiVe 378 LIME aad eee rosas dad RES 380 USerbDit 386 User downloadable filters 147 designing 401 overview 2 401 User filters 401 see user downloadable filters User weighting filters see user downloadable filters WD 33 sn ocaso as 386 V FS generator reference 122 Valdi DIC e 4 eke eo awe ee ee 386 Value Regulation parameter 356 Variable phase sine waveforms 104 VIEW MenU fs be e ea 15 Visual Basic aaa te Bae oe Se eG 351 Volume baf 2 eee ee a 337 W wav file creating a multitone wav file 237 242 ATS 2 User s Manual index Walking Ones and Zeros waveforms Digital Generator 119 WAV file export a a oe kG SES a e RR 409 WMDOIG ccoo bode bbs 411 Waveform file Support 412 Waveforms Analog Generator 81 Digital Generator 103 Weighting filter 145 Windows FFT 397 Word Width see Resolution Word digital audio signal 385 Workspace
417. pter 5 Signal Analysis with ATS 2 Digital Audio Signals 42 are routed to the ATS 2 Analyzer where a number of different analysis in struments can be applied See Chapter 6 for detailed information on the Analog Input panel The Analyzer is discussed below Digital Audio Signals The Serial Digital Interface Signal Digital audio is transmitted and received on the serial digital interface signal The interface signal has characteristics which can be measured and tested and ATS provides the capability to do this in the Digital Input Out put DIO panel and to a greater extent in the Analyzer instrument called the Digital Interface Analyzer which is available as a component of the Per formance Upgrade Option Since the interface signal carries the digital audio some characteristics of the interface signal can be observed by measuring the audio effects on the embedded signal The DIO also configures ATS 2 to receive the data stream from the digi tal input and passes the embedded audio on to other ATS 2 functions All the input and output configuration of the digital interface signal is ac complished from the DIO panel See Chapter 7 for detailed information on the DIO panel Digital Audio Generation ATS 2 can produce a wide range of digital audio signals in the Digital Generator see Chapter 9 After generation the digital audio is embedded in the serial digital interface signal before being applied to the input of a d
418. put panel or simply the DIO panel The DIO panel serves as the hub for all digital signal input and output configuration Additionally a number of interface signal parameters can be monitored or changed on the DIO panel and on the linked Status Bits panel See Chapter 2 for an explanation of the characteristics of digital audio signal including the serial digital interface signal and the embedded digital audio it carries The digital input and output hardware connections are dis cussed in Chapter 4 2 Digital 140 of parta zl africa z feo ES E 24 Bits 4 Bite Off Output Rate H Ort Meas Input Rate 45 0000 kHz FODH2 to 100kHz Figure 14 The Digital Input Output DIO panel ATS 2 User s Manual 51 Chapter 7 The Digital I O Panel The DIO Output Section On the left of the DIO panel is the Output section which includes con figuration settings and a number of output signal impairment selections The rest of the panel is the Input section which includes input configura tion and monitoring A button near the bottom of the panel accesses the Status Bits panel Figure 15 The DIO Output Section EQ Curve The DIO Output Section 2 Digital 1 0 Output Fomat xLR Sample rate D SR 48 0000 kHz Voltage 5 000 pp Resolution 24 Bits i CUA Scale Freg by Output Rate Polarity Send errors T Invalid Jitter Generation Jither Type Sine
419. put units The g x unit is computed from a x x scale h x output Like the scaled voltage and resistance units h x en ables you to scale digital output units The h x unit is computed from h x scale ATS 2 User s Manual 381 Appendix A Units of Measurement DCX 127 Units 382 ATS 2 User s Manual Appendix B The Digital Audio Signal Almost all digital audio signals are a form of pulse code modulation PCM When an analog signal is digitized the waveform is sampled at a regular rate the sample rate and the amplitude of the waveform at each sampling instant is acquired Each value is encoded as a binary number and each number is called a digital word Placed end to end the words form a string of pulses representing the binary numbers at each sampling instant PCM audio can be characterized in a number of ways chief among them the sampling rate used and the dearee of resolution of the numbering system The sample rate can be low such as the 8 kHz rate used in tele communications or high such as the 192 kHz rate sometimes used for high performance music recordings Common sample rates are the 44 1 kHz rate used in Compact Disc CD recording or the 48 kHz rate used in broadcast and professional audio recording A key consideration in sample rate selection is signal bandwidth which is always limited to one half the sample rate referred to as Fs 2 or the Nyquist frequency The numerical resoluti
420. quencies This will list all of the fundamental frequencies in your waveform in the sweep table m Harmonics If you select Harmonics the Multitone Creation Utility will calculate the harmonics you specify for each of the fundamental tones and will list these frequencies in the sweep table You can specify the range of harmonics you desire and the utility will generate them up to ATS 2 User s Manual 241 Chapter 13 The Multitone Audio Analyzer Creating Multitone Waveform Files 242 the Nyquist frequency You can optionally select to only list the odd harmonics m IM Products If you select IM Products the Multitone Creation Utility will calculate the intermodulation sum and difference products to the order you specify for each combination of fundamental tones and will list these frequencies in the sweep table You can specify a listing of IM Products up to the order you desire and the utility will generate them up to the Nyquist frequency You must choose at least one of these selections for a valid sweep table definition If you want only a subset of these frequencies you can delete rows from the sweep table using the Data Editor or the Attached File Edi tor Creating an MS RIFF wav File If you have requested a wav file the following dialog box will open You can specify the length of the file the resolution in bits and the type of dither to be used See page 120 for more information about dither Figure 203 ATS 2
421. quency tone that can be assigned any frequency in the range of 40 Hz to 500 Hz The frequency of the second sinewave set in the High Freq field can be anywhere in the range from 2 kHz to 50 of the sample rate The low frequency sinewave is linearly combined in 4 1 amplitude ratio with the high frequency sinewave Wfm IMD SMPTE DIN 1 1 This is the same as the Wfm IMD SMPTE DIN 4 1 selection except that the amplitude ratio of the low frequency sinewave to the high fre quency sinewave is 1 1 Squarewave Figure 89 Digital Generator Squarewave PAIS A Ox Waveform tar Square y Frequency 1 0000 kHz nie Wfm Square The squarewave amplitude is calibrated in peak equivalent sinewave terms See Amplitude Control and Units on page 102 112 ATS 2 User s Manual Choosing a Digital Generator Waveform Chapter 9 The Digital Generator The frequency range for squarewaves is from approximately 2 Hz to 1 6 of the sample rate 8 kHz at a 48 kHz sample rate 7 35 kHz at a 44 1 kHz rate In order for the squarewave be synchronous with the sample rate and have a time symmetric duty cycle the available squarewave fundamental frequencies within that range are limited to even integer submultiples of the sample rate with the highest frequency being SR 6 and the lowest be ing SR 2 4 For example at a 48 kHz sample rate the highest squarewave frequen cies are m 8 kHz 48000 6 m 6 kHz 48000 8 m 4 8 kHz 48000 10 m 4 0
422. r mation Comment You can optionally enter comments in the Comment Edit box which is displayed on the Graph panel below the Graph Legend On the Graph Options menu click Comment to view the Comment Edit box on screen Your comments will always print at the bottom of a tabular data printout File gt Print gt Data When printing a graph File gt Print gt Graph you have the option of printing the comments or not depending on your selections on the Page Setup dialog box discussed on Page 330 New Data To clear the graph and the Data Editor click New Data in the Graph Options menu This has the same function as the command File gt New gt Data This command actually removes the data from memory not just from the display and cannot be undone ATS 2 User s Manual 295 Chapter 16 Graphs Graph Legend Graph Buffer F igure 230 Gr ap h Buffer Graph Butter Store Trace Alt Fo commands Recall Trace FS Delete Trace Ctrl FE The Graph Buffer is a dedicated display memory in which you can store a trace or set of traces as a reference and then recall the reference for comparison to a graph of current data When you click Graph Buffer a small submenu appears with these choices m Store Trace Click Store Trace to put the traces currently on the Graph panel into the Graph Buffer memory You may also use the keyboard combination ALT F8 Recall Trace Hide Trace This choice toggles between Recall Trace and H
423. r click Autoscale to let ATS scale the display in response to the signal For most parameters you can make the choice between a logarithmic or linear scale by clicking the Log or Lin option buttons The Increment field is only available for settings and enables you to specify the minimum increment by which the setting can be changed Using a Bar Graph for Readings To use a Bar Graph for readings you must create the graph while an in strument reading field is highlighted or you must select an instrument read ing parameter from the Connection browser in the Bar Graph Setup panel e Bar Graph 1 Analyzer Level _ lol x Min 72 299 dBFS IA A ES AS A A AO 100 50 B0 40 20 H dBFS Nominal Level should be 12 dBFS Figure 238 Typical Bar Graph for readings with optional comment Bar Graph readings are displayed as green digits and also as a horizon tal magenta bar The bar will respond to the signal reading in real time sim ulating an analog meter You can remove the bar display by selecting Display Digits Only on the Setup panel ATS 2 User s Manual 305 Chapter 17 Bar Graphs Using a Bar Graph for Settings 306 When the magenta bar moves to show a changing signal a narrow gray horizontal bar will appear on the magenta bar to indicate the history of minimum and maximum readings This can be reset by clicking the Reset button or the Reset Min Max button on the Setup panel You can also add a Tar
424. r all passes are summed and then divided by the number of passes During an averaging process the Status Bar at the lower left of the ATS workspace counts down through the number of acquisitions as they are performed Averaging factors from 2 to 4096 are available A selection of 1 dis ables averaging Synchronous Averaging The primary purpose of synchronous averaging is to reduce noise levels in order to provide more accurate measurements of signals which would otherwise be lost in the noise Synchronous averaging is performed on the acquired time domain sig nal so it can be used when viewing noisy signals in the time domain in os cilloscope view 100u 100u Tr Tr E n l J t J WJ 50u Adu 25u Zou O j 250 25u 50u 50u F5u Tr Pad 10014 100uE 0 s00u Figure 138 A time domain view of 85 dBFS and 100 dBFS 16 bit sinewave signals normal dither no averaging Figure 138 shows a time domain display of 85 dBFS and 100 dBFS 16 bit sinewave signals with normal triangular dither and no averaging All that can really be seen is that one signal occupies the five lowest amplitude digital codes and the other occupies the three lowest codes 168 ATS 2 User s Manual Averaging Chapter 11 The Spectrum Analyzer 4 100u 100u fou fou 50u 0y 254 254 T Ll 25u 25u 50u 50u TTE TE 75u F5u 100u5 al 100u Ll SO0u Figure 139 A time domain view of 85 dBFS and 100 dBFS 16 bit sinewave
425. r s Manual Copy to Sweep Panel command 289 Counter tuned filter see bandpass bandreject filter 150 Coupling 127 Spectrum Analyzer 166 with common mode testing 128 Crosstalk measurements Audio Analyzer 133 Crosstalk ratio see crosstalk measurements Ctrl F6 see Sweep Reprocess Data command 287 Cursors OFaDh lt 4648444644444 289 D Dalal chee eede ew PE eH KORG 261 Data 3 4 5 65 coca ea ass bh a 264 Data Editor datafiletypes 0 310 data that will not graph 307 editing the current data 309 graph legend linkage 296 invalid dataflag 2 309 lower limitflag 309 314 overview 307 regulation flag 309 saving test data 310 timeout flag 309 upper limit flag 309 314 Data file aaa aaa 310 314 Data test oaoa aa a aa 308 dB discussion 372 OBES eee oros 376 dBr generator reference 122 DC coupling 127 DCX 127 UNIS dao eee ee kee ewe eee es h 381 decibel discussion 372 Deemphasis digital audio 65 also see preemphasis Delay time pre sweep 269 settling ck 4 we ee ewe eee wD oe 280 Delta Compute algorithm 323 Dependent variable 261 Detector function meter 141 DGe
426. rameters but also configure the sweep and graph engines for the display you desire Start or Stop values and sweep direction for example are clearly defined An internal sweep is defined by panel set tings The Source 1 independent variable in an external sweep however is driven by meter measurements not by generator settings In the case of the CD test disc the measured frequency of the received test signal be comes the Source 1 information and the measured channel A and B am plitudes become the Data 1 and Data 3 results So in an external sweep ATS must monitor the input signal readings to extract sweep controls from that signal ATS has no way to predict the be havior of an external signal and you must specify considerations such as the range and direction of the sweep when to graph a point or when to start and end the sweep Even with these specifications extracting usable sweep controls from in put signals can be difficult Noise flutter or level changes can all cause an external sweep to act erratically or graph spurious points ATS 2 User s Manual 271 Chapter 15 Sweeps and Sweep Settling External Sweeps ATS provides a number of special controls to set up an external sweep and produce stable results External Sweep Operation Browser Sweep_Source 1 x Instrument Parameter Frequency A Amplitude 4 Amplitude E Frequency B DCx 127 Level 4 Digital Generator Level B Digital 110 Time
427. rd Acquisition Length Transform Length 64 enero d OH SEE GSS Spectrum Analyzer Window Selection Hann WIACOW ses test bee Ses SO ee ESS HH SE Blackman Harris Window 0 Flat TOO WINAOW 4 63455 eee eee GES eG ESS Equiripple WINdOW 2 465 85 65445 rea Hamming WINGOW 2 0 6 446 4 2446 ow o ee we eee oO Gaussian WINGOW oz sn es ew Heme ed ee BAR we Rife Vincent Windows 020 None No Window or Rectangular Window None movetobincenter Quasi AC Coupling aoao 0 2 2 Averaging kan See eee HEE EH IA Synchronous Averaging 04 Signal Alignment for Synchronous Averaging Sync without re align Syn real iras nora as Synchronous Averaging for Move to bin center OPeratiONS cu askance cres rare Synchronous Averaging and Frequency Domain Views Power Spectrum Averaging Display Processing 0 00 2 ee eee eee Waveform time domain Display Processing IVECFDCIALe gusta wee owen Ge een ee Bees wee eS Display SampleS ee eae Seas oe eo ee ee ee ee PEAK VAIUGS wo pw ew a ee Re AA Absolute Values 2 20 2200 502 08 ATS 2 User s Manual Vii Graphic Aliasing o 00208004 176 Spectrum frequency domain Display Processing 176 FFT Start Time 2 000 a eee ee
428. re An ATS bitmap graph looks like the screen image showing the graph as white and colored lines on a black background Files with the filename extension bmp are bitmap files A vector graphics file describes the image in programming code and such an image can be resized with no degradation The resolution of a printed vector graphics file is dependent only on the resolution of the printer Vector graphics files are edited with draw graphics soft ware and are usually easier to modify than bitmap files An ATS vector graphics image shows the graph as black and colored lines on a white background A graphic with the filename extension emf is a vector graphic file ATS 2 User s Manual 335 Chapter 20 Printing and Exporting Copying a Window or Screen to the Clipboard 336 ATS 2 User s Manual Monitoring Headphone Speaker Monitoring ATS 2 has an internal speaker and a rear panel headphone jack for monitoring of audio signals at different points in the system The speaker and the headphone jack carry a monaural signal selected from the list on the Headphone Speaker panel The headphone jack is a standard 3 5 mm tip ring sleeve TRS jack wired to apply the monaural signal to both the left and right sides of ordi nary stereo headphones When a plug is inserted into the headphone jack the internal speaker is disconnected The Volume Bar Figure 266 The Volume Bar The headphone output and the internal speaker
429. re 110 shows a conceptual block diagram of the Audio Analyzer with the 2 Channel Ratio function selected 132 ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer The 2 Ch Ratio function displays the ratio of the signal amplitudes in the two channels A and B The Channel A Function meter shows the ratio A B and the Channel B Function meter shows the ratio B A 2 Ch Ratio may be expressed in dB or X Y units The 2 Ch Ra tio function is useful while balancing stereo channels for example or for measuring gain or loss by connecting the Audio Analyzer A channel across the DUT input and the B channel across the DUT output Crosstalk Function Figure 111 shows a conceptual block diagram of the Audio Analyzer with the Crosstalk function selected A A CHANNEL A PEAK 1 442 Vp METERS n E EEEE wg A CHANNEL B z CHANNEL A CHANNEL A CHANNEL A CHANNEL A x Digital Analog Analog AES A to D Peak Receiver Converters Detectors Ranging PETO Input Coupling a 4 a l l z m CHANNEL B CHANNEL B CHANNEL B CHANNEL B Inputs DIO Analog Input Panel tan nunggu nnn b annn A sn nnnnnnn nnmnnn anmnun A O O 4 Frequency References CHANNEL A Digital CHANNEL A AC DC 11 000 kHz FREQUENCY Coupling CHANNEL B METERS CHANNEL B CHANNELA CHANNEL A Detectors CHANNEL A Ranging RMS 1 005 V J LEVEL
430. re 275 The ATS Regulation panel Regulation lolas ala e le 100 wv E Stepsize w E y E000 sec Here s another example you d like to find the exact frequency at which the DUT response is 3 dB down from the midband level reference ATS s regulation function can adjust a generator frequency while monitoring the ATS 2 User s Manual 355 Chapter 24 Regulation DUT output amplitude guiding the generator up and down to the precise frequency at which 3 dB is measured Figure 276 The ATS Regulation Target Rei nn j Parameter Browser Instrument Amplitude A Amplitude B Frequency 4 Frequency B Level A Level B Analog Generator Digital Generator Digital I O Sync Ref Time Auxiliary Y Show Readings The Regulation panel enables you to select m a Target parameter This is the parameter ATS is monitoring as it is steered toward the target value Use the target browser to select the target parameter from the ATS instrument readings provided a target Value This is the reading from the DUT that you are trying to attain m a target value Tolerance This is the range around the target value that is acceptable for your test Figure 277 The ATS Regulation Source MREEASEAE i Browser Instrument Parameter ChB Amplitude Digital Generator Digital I O Sync Ret Time Auxiliary Y Show Settings m a Source parameter This is the ATS setting whi
431. re jitter measurement displays and settings and a button to open the Status Bits panel Format Selections Format KLF bal Sample rate 15A Input Voltage Resolution 4 The first setting field is Format Select the serial digital interface input format and connector s from the list XLR bal This is the balanced digital input When the impedance at Z In is set to 110 Q this input satisfies the electrical aspects of the AES3 professional standard a BNC unbal This is the unbalanced digital input When the impedance at Z In is set to 75 Q this input satisfies the electrical aspects of the AES3id professional standard with impedance at HiZ this input satisfies the IEC60958 3 consumer standard a Optical This is the Toslink optical input GenMon This selects the generator monitor path which bypasses the external digital input connector and instead attaches the digital input to the Digital Generator output via an internal connection Dual XLR bal These balanced digital inputs I and II are used in conjunction with each other as explained in the Dual Connector Mode sidebar on page 53 ATS 2 User s Manual 61 Chapter 7 The Digital I O Panel The DIO Input Section 62 Input Impedance Figure 26 The DIO Input Impedance Connector Connector I selections Zn 110 Ohrnz f Connector C Connector Il To the right of the Format selection field is the Z In field which
432. red in AP Basic in the Macro Editor as you work On the Utilities menu a checkmark will remain next to the Learn Mode choice while ATS is in Learn Mode and the shape of the mouse pointer will change to that of an audio cassette indicating that a recording is being made Choose Utilities gt Learn Mode to exit Learn Mode The mouse pointer will return to its normal shape the checkmark next to Learn Mode will disappear and you will be prompted to save the macro See Chapter 23 for more information on automating tests with AP Ba SIC Multitone Creation A comprehensive multitone creation utility has been provided with ATS 2 to facilitate making custom waveform files for multitone testing Choose Utilities gt Multitone Creation to open the program See Creating Multitone Waveform Files on page 236 ATS 2 User s Manual 369 Chapter 25 Configuration and the Utilities Menu Multitone Creation 370 ATS 2 User s Manual Appendix A Units of Measurement Introduction Many different units of measurement are used to describe audio signals and audio system components and characteristics ATS offers a wide choice of units of measurement for both setting and reading values m Values can be expressed in absolute terms such as the volt the watt the ohm the hertz and the second m Values can also be displayed as the ratio of one value to another with units like the decibel or percent m In addition ATS provides relative units w
433. reference for relative frequency units used in the Digital Interface Analyzer Relative frequency units are useful for dis playing the spectra relative to the interface sample rate or relative to the jit ter frequency There are several choices of relative frequency units in ATS including F R dHz Hz octs decs d and dPPM These are available any ATS 2 User s Manual 211 Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer panel settings time that the Sweep Source or Data parameter is set to Intervu Fre quency For a complete discussion of these units and their definitions see Appendix A Saving and Loading Interface Waveforms As with other ATS tests you can save the setup and results of any Digi tal Interface Analyzer test as an ats2 test file The acquired waveform in the Digital Interface Analyzer acquisition buffer however is not saved as part of a test If you want to keep the acquired data record for further anal ysis you must save it as an aai Audio Precision Acquisition Interface ac quired waveform file When the Digital Interface Analyzer is selected as the Analyzer instru ment the File gt Open gt Intervu Waveforms and File gt Save As gt Intervu Waveforms menu commands become available These commands allow you to save a Digital Interface Analyzer Intervu acquisition waveform to disk as an aai file or to open an existing aai Intervu file and load the waveform into the acquisit
434. rger waveform 90 00 deg has been entered in Phase B A field causing B the smaller waveform to lag A Phase B A field will cause the Channel B output to lag the Channel A out put See the illustration below Wfm Sine Stereo Figure 79 Digital Generator Sine Stereo WWW o wwf Sine ha Steren r Frequency 997001 kHz lh Frequency 2 12 00000 kHz Ch B P Auto O e Track s T Invert mea corroe aa Di fi 000 FFS Armplitude sf This waveform selection produces independent sinewaves on Channel A and Channel B The Frequency field sets the frequency of the Channel A signal and the Frequency 2 field sets the frequency of the Channel B signal Their amplitudes are independently set by the two Amplitude fields unless the Track A box is checked in which case the amplitudes are equal and controlled by the Channel A Amplitude field Wfm Sine Dual This selection produces two independent sinewaves which are summed to create a complex waveform This complex waveform is sent to both channel outputs ATS 2 User s Manual 105 Chapter 9 The Digital Generator Choosing a Digital Generator Waveform 106 Figure 81 Digital Generator Sine Dual Digital Generator O x wfm Sine Dual Frequency 997001 kHz ChA a Frequency 23 89971 Hz i ChE Cual Amp Fratio 250 0 mar T Auto On e Track A T Invert ema OUTPUTS ere eRe Invert 1 000 FFS v Amplitude
435. rm file and the right half defines what will go into the second section of a stereo waveform If the File gt Save As gt Mono Waveform option was selected the right half of the dialog will be gray You can save the entire acquisition record or just the portion currently designated for transformation from either the channel A or channel B ac quisition data If the transform length is shorter than the acquisition record length the waveform file will be correspondingly smaller Opening Acquired Waveforms Figure 197 ATS Multitone Audio Acs Analyzer Open Stereo Waveform dialog box ATS 2 User s Manual Acquired Waveform Files Chapter 13 The Multitone Audio Analyzer To open an acquired waveform file select the File gt Open menu com mand choosing either the Stereo Waveforms aas or Mono Wave forms aam as the file type You can load one waveform or simultaneously load both waveforms into memory from a stereo file and you can choose to assign the wave form to either channel and to the acquisition or the transform buffers A mono file only contains one waveform but you have the same flexibility to load it into either channel or either buffer When opening a mono wave form file the right half of the dialog box will be gray If acquisition in a file to be opened is greater than the length of the specified buffer an error warning will be displayed and the file will not be opened If the acquisition length in the file i
436. rmed in the ATS 2 hardware including storage of signals acquired for DSP waveform display or FFT analysis The ATS 2 Front Panel DIGITAL INPUT z I ANALOG OUTPUT amp hf 2 ANALOG INPUT CHANNEL E EHAMMEL A CHANHEL E Mi 1 fe e 1 CHANNEL A O E O O PAL Digital Output Digital Input Analog Outputs Analog Inputs Power Indicator Figure 6 ATS 2 Front Panel The main digital and analog signal input and output connectors are on the ATS 2 front panel with a lighted power on indicator ATS 2 User s Manual 31 Chapter 3 The ATS 2 Hardware The ATS 2 Rear Panel m THE DIGITAL OUTPUT The ATS 2 digital output can be routed to the balanced XLR male I connector the unbalanced BNC connector or the optical connector by software selections When the dual connector output configuration is selected both the I and II connectors are used together m THE DIGITAL INPUT The ATS 2 digital input can be routed from the balanced XLR female I connector the unbalanced BNC connector or the optical connector by software selections When the dual connector input configuration is selected both the I and II connectors are used together m THE ANALOG OUTPUTS The ATS 2 analog outputs for both A and B channels are available as balanced signals at the XLR male connectors and as unbalanced signals on the BNC connectors a THE ANALOG INPUTS The XLR female balanced connectors and the BNC
437. rol of dither and m the lower area which provides fields to set references We will first look at general topics of setting frequency and amplitude and turning the generator ON and OFF then we will examine the many waveform selections available in detail last we will look at choosing the dither type and setting the digital references 100 ATS 2 User s Manual The Digital Generator Panel Chapter 9 The Digital Generator Frequency Units Figure 71 Setting the Digital Generator l Digital Generator lel Frequency wim Emm E Cha Ch B ODO ZE 694 275 udHz 1 00 000 lt Hz 0 00 cent W Track amp 0 00000 octs TF Invert Frequency may be expressed in absolute units hertz and in a variety of units relative to the value entered in the Reference Freq field See Digi tal Generator References on page 122 and Frequency Units on page 37 2 Changing units does not change the frequency of the generator The ex isting frequency will simply be re stated in the new units Also the value displayed after pressing Enter may differ slightly from the value you typed in since ATS will step to the nearest frequency increment Output On Off and Channel Selection Figure 72 Digital Generator ON OFF Y auto On y aka Both channels and the Outputs are shown Inven ME OUTPUTS Em EAB Invert invert The Digital Generator signal outputs are toggled ON and OFF by the OUTPUTS button Additionally each channel o
438. ronous This process takes more time than the Synchronous selection and should be used only if the received signal has passed through a device that has slightly shifted its frequency Windowed applies a Hann window to the signal before transformation This choice offers poorer selectivity than the two synchronous selections and should only be used in situations where frequency shifting of the multitone signal has occurred and the use of the Freq Corrected mode of fers insufficient frequency shifting range or is otherwise undesirable ATS 2 User s Manual Triggering Chapter 13 The Multitone Audio Analyzer Triggering Figure 194 Multitone Triggering Tinga Digital Gen selections Diolta Gen Trigger Delay Tight The Multitone Audio Analyzer has seven triggering modes a Off m Digital Gen m Analog Gen m Tight m Normal m Loose Trig In Ext Off Off results in untriggered or free running operation Acquisition and pro cessing begin as soon as the Go button pushed Digital Gen and Analog Gen The ATS 2 generators issue a trigger when the first sample of the Multitone waveform is generated When Digital Gen or Analog Gen is selected the Multitone Analyzer triggers from that source Digital Gen and Analog Gen triggers provide consistent stable operation and are the recommended triggering modes for locally generated multitones The generator triggering modes are the only triggering modes that will re turn a
439. rsor for that trace will be unassigned Cursors may be assigned to different traces only if the two traces have compatible parameters or unit domains If the graph is a nested sweep the Source 2 value for the selected trace is shown in a display box at the top of the graph ATS 2 User s Manual Chapter 16 Graphs 291 Chapter 16 Graphs The Graph Options Menu a Audio Precision A A VIEW WAVEFORM Amplitude ys Time 1 114 V 1 166 V 1 114 V 1 167 V Figure 228 Graph Cursors 1 and 2 on different traces Cursors are restricted to regions of valid data and cannot be moved to the blank regions on a trace that represent invalid results See Data Dis play Flags page 309 Scroll Bars If you have zoomed to a particular graph region and would like to view another region open the Graph Options menu and click Scroll Bars This provides an easy way to move around a graph which extends beyond the Graph panel window If you don t need to scroll click again on Scroll Bars The scroll bars will disappear 292 ATS 2 User s Manual The Graph Options Menu Chapter 16 Graphs Title and Labels Figure 229 Graph Title EZME and Labels dialog box You can modify or add titles and labels to your graph On the Graph Op tions menu click Title and Labels A dialog box will appear for you to make your entries The Company Name setting has its source in the ATS Configuration panel where you can enter a company name or other info
440. rter 010x xxxL Magnetic 110x xxxL Digital Broadcast 001x xxxL and 0111 xxxL Musical Instrument 101x xxxL DVD 1001 100L Present A D Converter 0110 OxxL Future A D Converter 0110 1xxL Solid State Memory 0001 xxxL Experimental 0000 001L source number bit 16 is LSB channel number bit 20 is LSB sampling frequency 0000 44 1 kHz 0100 48 kHz 1100 32 kHz XXXX 24 kHz XXXX 22 05 kHz XxXxX 192 kHz XXXX 176 4 kHz XxXxX 96 kHz XxXxX 88 2 kHz clock accuracy 10 Level I 50 ppm 00 Level Il 1000 ppm 01 Level Ill variable pitch shifted reserved Te word length field size 0 Maximum length 20 bits 1 Maximum length 24 bits word length if bit 32 1 if bit 32 0 not indicated not indicated 24 bits 20 bits 23 bits 19 bits 22 bits 18 bits 21 bits 17 bits 20 bits 16 bits reserved reserved ATS 2 User s Manual 387 Appendix B The Digital Audio Signal The Serial Digital Interface Signal Byte Professional format channel status fields Pro con Non Lock Sample frequency 1 audio bit 0 1 2 3 4 5 6 7 Channel mode User bit management bit 8 9 10 11 12 13 14 15 Use of auxiliary mode sample bits Source word length Alignment level bit 16 17 18 19 20 21 22 23 Channel Identification for multichannel application 26 27 28 29 30 TO smer 34 35 36 37 38 Reserved 41 42 43 44 45 Alphanumeric channel origin data first character 49 50 51 52 53 Alphanumeric channel origin data 58 59 60 Alphanumeric channel
441. rtion Analyzer Instrument Harmonic Distortion Analyzer Ch A Inp Audio Analyzer FFT Spectrum Analyzer INTERYU Digital Interface Analyzer FASTTEST Multitone Audio Analyzer Harmonic Distortion Analyzer Harranedc Sir 1 panel by choosing Panels gt Analyzer or by the keyboard shortcut To use the Harmonic Distortion Analyzer first open the Analyzer 3 Ctrl Y or by clicking the Analyzer button on the Toolbar ig Now select Harmonic Distortion Analyzer from the list on the Ana lyzer panel This loads the Harmonic Distortion Analyzer program into DSP Signal Inputs ja Analyzer Aa Instrument Harmonic Distortion Analyzer ChA input Analog ChB Figure 206 Harmonic Distortion Analyzer panel inputs The Input field of the Harmonic Distortion Analyzer offers two sig nal input selections Digital and Analog These choices access the signals routed from the Digital Input Output DIO panel or the Analog Input panel respectively Digital signals are applied directly to the Harmonic Distortion Ana lyzer DSP analog signals are first digitized by precision ADCs selected on the Analog Input panel before being applied to the Harmonic Distor tion Analyzer To configure analog input connectors range coupling select ADCs bandwidth etc go to the Analog Input panel see Chapter 6 To config ure digital input connectors digital input format and other aspects of the in terface go to the DIO panel see
442. ry standard General Purpose Interface Bus GPIB Basic installation with GPIB is covered in Getting Started with ATS 2 For GPIB development and programming order the ATS 2 GPIB Program mer s Reference Manual See page 31 for more information about ATS 2 with GPIB ATS 2 User s Manual 7 Chapter 1 Introduction GPIB Documentation for ATS 2 8 ATS 2 User s Manual The ATS Control Software Overview Most of your interaction with the ATS 2 system will be through the ATS control software Once ATS 2 is plugged in turned on and connected to your device under test or DUT you will be making all your adjustments and taking all your readings from your computer screen The ATS control software is a powerful and complex program and most of this book is dedicated to exploring and explaining its many capabilities In this chapter we ll look at an overview of the software features and learn the basics of operating the system With Option GPIB hardware installed ATS 2 can also be controlled by the industry standard General Purpose Interface Bus GPIB See page 31 for more information about ATS 2 with GPIB The User Interface Like many Windows applications the ATS user interface has a menu bar a status bar toolbars and a workspace With these tools you can save test and data files export and print measurement results configure both the hardware and software to your needs access online help design and launch automated pro
443. s Source A Function A The sum of these signals Source B Function B The sum of these signals The Monitor Outputs MONITOR OUTPUTS Q A SOURCE B Figure 268 The MONITOR OUTPUTS connections A FUNCTION There are four MONITOR OUTPUTS available on BNC connectors on the ATS 2 rear panel These are unbalanced outputs with a voltage range up to 4 Vpp and a source impedance of 422 Q The MONITOR OUTPUTS are intended for oscilloscope or other mon itoring These outputs are not calibrated and should not be used for mea surements ATS 2 User s Manual 339 Chapter 21 Monitoring The Monitor Outputs 340 The SOURCE Outputs The SOURCE A and SOURCE B outputs carry the audio signals as they appear at the inputs to the Analyzer instrument in use after rang ing the point where the Level or Peak meter readings are taken If the Digital Interface Analyzer is the instrument the monitored signals are the embedded audio The SOURCE monitor outputs are the same signals as can be selected on the Headphone Speaker panel Monitor Source selections The FUNCTION Outputs The FUNCTION A and FUNCTION B outputs carry the audio signals as they appear after a given Audio Analyzer function is applied The FUNCTION monitor outputs are the same signals as can be selected on the Headphone Speaker panel Monitor Function selections Signal is only available at the FUNCTION monitor outputs when using the Audio An
444. s This can be reset by clicking the Reset button or the Reset Min Max but ton on the Setup panel ATS 2 User s Manual Chapter 18 Editing Data and Setting Limits The Data Editor Any data collected by the Sweep panel including stimulus and response data from real time sweeps and bin centers and values in batch mode measurements is temporarily stored in memory during an ATS session This data can be replaced deleted appended to stored on disk and so on ATS data which has been stored on disk as an atsa file or within a test can be loaded to become the current data in memory The Data Editor panel gives you a view of the current data in a table much like a spreadsheet page The Graph panel uses these values to draw the traces on the X Y graph display if you change a value in a Data Editor cell the corresponding point on the graph will move Certain data will not graph including a single point sweep a sweep which contains changes of direction in Source 1 values or in graphs where two unit domains already occupy the left and right Y axes another data set expressed in a third unit domain The Data Editor however shows all the data in current memory even data which will not graph If you have accidentally configured a sweep that will not graph the Data Editor can verify whether or not the sweep has exe cuted and allows you to examine the data to find the error The Data Editor is closely tied to both the ATS Sweep an
445. s it through to the Analog Generator outputs This is a convenient way to convert a digital test signal from a CD for example to an analog test signal If the REF IN signal is stereo the output signal will also be stereo In Pass Thru mode the sample rate of the Analog Generator DACs is set to the ATS Output Sample Rate OSR indicated by the Sample Rate field on the generator panel which shows OSR in this mode The OSR which is set on the DIO panel has a range of 28 8 kHz to 108 kHz The REF IN signal is sample rate converted to the OSR The REF IN signal sample rate must be between 28 8 kHz and 108 kHz Additionally the ratio of the REF IN sample rate to the OSR must fall in the range between 1 3 to 3 1 or stated another way OS lt REF INSR lt OSRx3 The sample rate converter is controlled by ATS to maintain the REF IN embedded audio at its original frequency As a result changing the OSR setting will not shift the audio frequency of the REF IN signal but it will af fect the signal s bandwidth To avoid attenuation and distortion in Spe cial Pass Thru the REF IN audio frequency must not exceed 0 47 x OSR The default setting of the OSR is 48 kHz To preserve bandwidth for most Pass Thru audio testing the OSR should not be set lower than 44 1 kHz The amplitude relationship between the REF IN signal and the Analog Generator output is such that a REF IN signal of 1 00 FS 0 dBFS will re sult in a correctly cali
446. s particularly in time domain oscilloscope presentations where the dc offset might otherwise cause the signal to be off screen Either selection may introduce dc error particularly on very low frequency signals Also see Triggering with Quasi AC Coupling on page 182 Averaging Figure 137 ATS Spectrum Analyzer come l er spectrum onl pl Averaging selections wal qe rE A FFT L gt Trigger Delay 0 00000000s 7 Source Free Aun Slope 7 P 128 56 References 519 deraj100 0 mers dere1o0 0 1024 Freq 1 00000 kHz wars 1 000 laoa The Spectrum Analyzer provides two fundamentally different averaging techniques for better ability to measure program material and noise or low level and other noisy signals These are m synchronous averaging and m power spectrum averaging Both techniques average the signal over a specified number of acquisi tions They do this by summing the signals from all acquisitions and divid ing the result by the number of acquisitions Synchronous averaging operates on the time domain signal which makes it useful not only for time domain oscilloscope display but also for frequency domain spectrum analysis since the source of the signal for spectrum analysis is the time domain signal ATS 2 User s Manual 167 Chapter 11 The Spectrum Analyzer Averaging Power spectrum averaging operates only on the frequency domain re sult After each FFT is performed the spectra fo
447. s of the sound waves This representation is often carried on an electrical signal called the interface signal Digital audio is processed mathematically in processes gathered together under the name of Digi tal Signal Processing or DSP The term digital domain refers to signals represented and processed in this fashion Other Documentation for ATS 2 Audio Precision publishes a wealth of material on our hardware and soft ware products about audio theory and on specific test and measurement techniques Here are some important documentation resources Getting Started with ATS 2 We recommend that you read Getting Started with ATS 2 before read ing any other ATS 2 documentation It is an introductory manual which will help you correctly set up ATS 2 install the software on your PC and fa miliarize yourself with the system Inside Getting Started with ATS 2 man ual you ll find m hardware and software installation instructions m an introduction to the ATS 2 system ATS 2 User s Manual 5 Chapter 1 Introduction Other Documentation for ATS 2 m a look at the key features of the ATS control software m a group of Quick Guide tutorials putting the ATS 2 system to use in simple tests and m AIS 2 specifications A copy of Getting Started with ATS 2 is shipped with every ATS 2 sys tem and is also published in electronic form as a PDF file available on the Audio Precision Resources Disc and as a download from the Audio Preci
448. s selected a Sample Rate field appears on the lower portion of the Analog Generator panel ATS 2 User s Manual 91 Chapter 8 The Analog Generator Choosing an Analog Generator Waveform Configuration Out Ohms Bal XLR C 40 150 65536 Figure 61 Selecting an Arbitrary Waveform Sample Rate Sample Rate You can select from 4 sample rate choices for the DACs m 65536 which is the lower fixed sample rate for the Analog Generator DACs m 131072 the higher fixed sample rate m OSR the Output Sample Rate set in the DIO panel ATS 2 offers two methods of setting DAC sample rates using the OSR selection Go to the first tab of the Configuration panel at Utilities gt Configuration to set the method you prefer as follows e Ifthe Set sample rate when loading generator waveforms checkbox is checked ATS will automatically set the DIO OSR to the sample rate of the file being loaded e If this checkbox is unchecked you must manually enter the sample rate you desire in the OSR field on the DIO panel u ISR the Input Sample Rate read from ATS 2 s digital input and displayed on the DIO panel The Arbitrary Waveform generation memory buffers of the Analog Generator and Digital Generator are shared If both generators have Arb Wfm selected as the waveform the same waveform file will be used for both and the same signal will be produced at both the analog and digital generator outputs Special Wa
449. s shorter than the buffer size erroneous analysis may result Combining Mono to Stereo To compare two single channel acquisitions made at different times or under different conditions open the file containing the first acquisition data Assign the waveform to channel A or B and load the data Then open the second waveform file and do the same this time loading the data into the opposite channel The resulting two channel acquisition can be transformed processed and viewed and can be saved as a new stereo waveform file Compatibility of Acquired Waveform Files The waveform files used by both the Spectrum Analyzer and the Multitone Audio Analyzer have the same format and with certain restric tions on length can be used by either instrument The Spectrum Analyzer has a larger acquisition buffer and can open waveform files up to 256k samples in length Multitone is limited to open ing files with acquisitions of 32k or fewer samples Also although any multitone waveform can be analyzed by the Spec trum Analyzer only properly formatted waveform files are useful in Multitone See Chapter 11 for more information about the Spectrum Ana lyzer ATS 2 User s Manual 235 Chapter 13 The Multitone Audio Analyzer Creating Multitone Waveform Files 256 Creating Multitone Waveform Files Many useful multitone waveforms are provided with ATS and can be found in the folder ATS Waveforms You can also make your own custom multitone wa
450. samples and the FFT lenath in samples as follows Acquistion Length FFT Length Maximum Start Time Sample Rate If the original signal acquisition was made with a negative value in the trigger Delay field negative values up to and including that same value may be used as FFT Start Time values permitting spectrum analysis of the pre trigger section of the acquired record Triggering i Trigger Figure 144 Spectrum Analyzer Trigger Delay 0 00000000 E Source selections A Free nite e rBY100 0 mFFS fe Slope f Pos Neg J ChA Auto Se Ch Fixed Sens Freg CAB Auto Line Mains Jitter Gen Chea Fired Ley CHE Fined Ley The Trigger section of the Spectrum Analyzer consists of the Source field a Sens sensitivity or Lev level field for certain trigger Source se lections and the Slope option buttons to select positive or negative slopes Acquisition of signal into the FFT acquisition buffer may start imme diately at Sweep Start or may wait for a trigger event depending upon the setting of the Source field ATS 2 User s Manual 177 Chapter 11 The Spectrum Analyzer Triggering The selections are Free Run ChA Auto a ChA Fixed Sens ChB Auto ChB Fixed Sens a Trig In Ext Digital Gen Analog Gen a Line Mains m Jitter Gen m ChA Fixed Lev ChB Fixed Lev Free Run When Free Run is selected signal acquisition begins immediately after Sweep Start
451. se 000 a a a 113 Arbitrary WaveforMS a a a a a a 114 Special WaveformS a a a a a a a a a a a a a 115 Wfm Special Polarity 115 Wfm Special Pass Thru 116 ATS 2 User s Manual Wfm Special Monotonicity 117 Wfm Special J Test 119 wfm Special Walking Ones and Walking Zeros 119 wfm Special Constant Value 120 Wfm Special RANdOM aoaaa aa a a a a a aaa 120 Dither A 120 Dither Type aoaaa aaa a a a a a a a a a a a a 121 Digital Generator References 122 Volts for Full Scale Reference 122 Frequency Reference 122 dBr Reference 122 Chapter 10 The Audio Analyzer 123 Overview 0 0 ee ee a 123 Loading the Audio Analyzer 124 Signal INPUtS sk be eee eee end Re DEDEDE EEA 125 The Level Meters 2 000005 ae 126 Level Meter Units 2 020004 126 ACandDCCoupling 2 2 804 127 Common Mode Testing and Coupling Issues 128 The Frequency Meters 2 200 128 MeterRanging 2 002 ee eee 129 Autoranging 000 eee eee ee 129 Fixed Rae 00 eee a eee 129 The Function Meters 2 2 500 130 Function Meter Measurement Functions 130 Amplitude Function 2
452. ser s Manual Restoring the ATS 2 Hardware Chapter 25 Configuration and the Utilities Menu On Append file data e Cycle trace colors When you are appending a sweep from disk to a sweep in memory using the File Append command and Cycle trace colors is checked the appended sweep will start at the next color in the current sweep and move normally through the color cycle If Cycle trace colors is unchecked the colors of the sweep you are appending from disk will be maintained and not overridden by the color cycle The Graph Copy to clipboard options are m Background Color e White As Metafile If White As Metafile is checked the Copy command copies the current graph to the Windows clipboard as a vector graphic drawing in the Windows metafile format The graph is rendered as black and colored lines on a white background e Black As Bitmap If Black As Bitmap is checked the Copy command copies the current graph to the Windows clipboard as a bitmap image in the Microsoft bitmap format The graph is rendered as white and colored lines on a black background as it appears in the Graph panel Restoring the ATS 2 Hardware If the ATS 2 hardware has lost power or its APIB connection the Util ities gt Restore Hardware command will set the instrument to the cur rent software settings Utilities gt Restore Hardware can also be used as a hardware reset if the instrument does not appear to be responding normally
453. serves as the reference for the relative ATS 2 User s Manual 151 Chapter 10 The Audio Analyzer References 152 frequency units octs decs Hz etc of Analyzer frequency meters V FS In some setups when ATS 2 is measuring a signal in one domain digital or analog you may find it more convenient to enter or view the equivalent of the signal in the other domain The V FS volts for full scale value is the analog to digital scaling value When testing an external ADC for example enter the value of analog input voltage that produces digital full scale output into this field Then you can select amplitude meter units as V Vp Vpp dBu or dBV to express the measured digital amplitude in terms of the analog input value to the converter In the same way the dBr A and dBr B reference values may also be entered as digital or analog domain units with the V FS reference value being used to scale the references Watts The watt is a unit of power not voltage Since power calculations are dependent on the circuit impedance the load impedance encountered in your test must be entered as a reference for accurate display of watts W measurements 8 Q is the default impedance for the watts reference dBm The dBm like the watt is a unit of power decibels relative to 1 mW Since power calculations are dependent on the circuit impedance the load impedance encountered in your test must be entered as a reference for accurate displa
454. set the impedance to HiZ or bridging Frequency Set the exact nominal frequency of the synchronization signal in this field For an AESS signal for example it might be 44 100 kHz or 48 000 kHz For a squarewave set Frequency to the rate of the external clock If the actual reference signal is slightly different less than 15 PPM from the value entered here synchronization will be achieved but all ATS 2 sam ple rates and readings will reflect the difference If the value entered is more than 15 PPM away from the actual reference signal frequency the in ternal crystal oscillator may not lock to the reference ATS automatically enters the two video sync rates for you These may be changed by entering a new rate if necessary Input Frequency When a suitable reference signal is present at the SYNC REF IN BNC for the selected Source format the Input Frequency field will display that signal s frequency This display aids in verifying the presence or ab sence of a sync signal and in determining the nominal frequency before synchronization is achieved Once ATS 2 has synchronized to the reference the Input Frequency field is grayed out since the measured frequency would be identical to Fre quency setting ATS 2 User s Manual TRIG IN Chapter 22 Sync Ref Trigger and Aux Out of Range Indicator The Out of Range indicator on the Sync Ref Input panel is lighted if the actual reference signal frequency is outside 15 PPM of
455. share a common vol ume control and mute switch which are available on both the Volume Bar and on the Headphone Speaker panel discussed below The Volume Bar is a toolbar that is enabled on the View menu By de fault the Volume Bar is visible and it will appear on every Workspace page Like the other ATS toolbars the Volume Bar can be attached at the top of the Workspace or can be dragged to float at any location in the page ATS 2 User s Manual 337 Chapter 21 Monitoring Headphone Speaker Monitoring 338 Drag the Volume slider with the mouse pointer to change volume When the slider is selected the left right arrow keys will also adjust the vol ume Put a check in the Mute box to turn off the Headphone Speaker out puts Headphone Speaker panel Figure 267 The Headphone Speaker panel a Headphone Speaker Monitor mono Source 4 Sources __ Source E Function A Function E Source 4 Source E Function 4 Function E Source Function Source B Function E The Headphone Speaker panel is available at Panels gt Head phone Speaker or by clicking the Headphone Speaker button on the Panels toolbar The Headphone Speaker panel repeats the Volume slider and Mute switch These are the same controls that are on the Volume Bar and the in dicators on the two displays track each other Below the Volume slider is the Monitor list which makes several audi ble monitor source choices ava
456. some way of excluding the transients there would often be meaningless points spread across the graph The process of sweeping can also add spurious results to the measure ment This is because the Sweep panel is stepping through Source 1 pa rameter changes and with each change both the system generators and typical DUTs need a moment to stabilize To address these considerations ATS has a sweep Settling panel to set a list of criteria which the measured parameter must satisfy before being ac quired These settling values can be adjusted for various measurement con ditions and goals with the result that clear and meaningful graphs or tables of data can be obtained ATS normally obtains settled data by discarding early measurements and plotting only later repeatable values after both the DUT and the ATS 2 generator and analyzer have stabilized ATS has default settling val ues in place when you launch the software but you can reset the defaults on the Settling panel to optimize settling for different measurements Set ATS 2 User s Manual Sweep Settling Chapter 15 Sweeps and Sweep Settling tling values are saved when you save a test file and are recalled when a test file is loaded The settling values only affect real time sweep measurements and in AP Basic macros OLE meter readings ATS panel meter readings and batch mode instrument readings are not settled The Settling Panel if Settling 0 Tolerance Floor Points
457. st You must first open the file in APWIN running in System Two mode and save it as a System Two test Then you must open that file in APWIN in Cascade mode and re save the test as a Cascade test See the diagram in Figure 296 for an illustration of the com plete test migration flow for all instruments and software You do not need to have System One System Two or System Two Cas cade hardware connected to your computer to import open or save test files as described These conversions can be performed while APWIN is running in Demo Mode DON T run the ATS software while APWIN is running in Demo Mode Macros for batch converting APWIN tests Multiple System Two Cascade tests can be imported into ATS in one translation operation You can select all the atc2 test files in a directory for batch conversion as is discussed in the next section However moving multiple older test files up the APWIN migration path shown in Figure 296 can be a slow process limited by APWIN s constraint of being able to open and save only one test file at a time To address this issue Audio Precision s technical support team have written macros that automate batch loading and saving of APWIN tests You can download these macros and find other information for the ATS 2 Test and Macro Translators at our Web site at ap com ATS 2 User s Manual 419 Appendix F Test and Macro Translators The Test Translator Using the ATS 2 Test Translator Figure 297
458. st effective at representing the signal envelope when the X axis span and the Sweep panel Points values are selected to produce approximately two plotted points per cycle of the waveform being graphed For example if an envelope display of tone burst waveforms of a 1 kHz signal 1 ms period is being plotted across a 50 ms span the Points value on the Sweep panel should be set to approximately 100 ATS 2 User s Manual 175 Chapter 11 The Spectrum Analyzer Display Processing 176 Graphic Aliasing Figure 143 An example of graphic aliasing where a large number of samples is represented by a small number of graph points resulting in the display of an alias waveform When the density of samples is high compared to the density of graph points requested by the sweep Steps setting many samples will be skipped and not plotted Depending upon the signal and settings wave forms very different from the signal waveform may be displayed This is called graphic aliasing ATS has provided several display processing modes discussed in detail previously that minimize graphic aliasing problems You can help avoid graphic aliasing in the following ways as appropriate to your test m Use a larger number of sweep Steps m Use a shorter sweep span m Use the Interpolate display processing mode Interpolate automatically switches from interpolation to bipolar peak sensing to avoid graphic aliasing m Use the Peak Values or Absolute Valu
459. st load a multitone waveform into one of the ATS 2 generators This waveform must have the same characteristics as the multitone being used for the test The audio output of the generator is not used but the waveform information is sent to inform the analyzer of the multitone conditions 216 ATS 2 User s Manual The Multitone Audio Analyzer panel Chapter 13 The Multitone Audio Analyzer The Multitone Audio Analyzer panel Figure 175 Loading the Multitone Audio Guti la Analyzer Instrument FASTTEST Multitone Audio Anal Audio Analyzer FFT Spectrum Analyzer INTERE Digital Interface Analyzer FASTTEST Multtone Audio Analyzer Harmonic Distortion Analyzer To use the Multitone Audio Analyzer first open the Analyzer panel The Analyzer panel is a command selection on the Panels menu and is also available by the keyboard shortcut Ctrl Y or by clicking the Ana E lyzer icon on the Toolbar Now select FASTTEST Multitone Audio Analyzer from the list on the Analyzer panel This loads the Multitone Audio Analyzer program into DSP Signal Inputs Figure 176 Multitone Audio Analyzer i Analyzer EE Signal Inputs Inztrument hultitone Audio Analyzer Ch A Input Digital Ch E The Input field of the Multitone Audio Analyzer offers two signal in put selections m Digital and m Analog These choices access the signals routed from the Digital Input Output DIO panel or the Analog Input panel respectively
460. sting file data This command begins the file creation process using the data from a test or data file for tone frequency level and phase settings See Use existing file data below a OK Like Use existing file data this command begins the file creation process but uses the settings you make on the Frequencies Menu for tone frequency level and phase settings See Frequencies Menu below a Cancel This command exits the Multitone Creation Utility making no changes in your current test or files on disk m File options This command opens the Supporting File Creation Options dialog box See below When you have made the settings you want from this panel click OK to create a waveform from the Frequencies Panel or Use existing file data to create a waveform from existing data As you initiate the file creation process by clicking OK or Use existing file data the Multitone Creation Utility will save your current ATS test as a temporary file named Makewave tmp This frees up the ATS workspace and memory buffers for file creation tasks When the Multitone Creation Utility is finished the file Makewave tmp is reloaded into ATS If you want to do further work with this test you should save it under its original filename or under a new filename of your choice Using Existing File Data This command begins the file creation process by using the data in mem ory or in a data file for tone frequency level and phase settings To cr
461. t and Macro Translators Macros from System One System Two and System Two Cascade can be directly translated for ATS 2 without intermediate conversions How ever it is helpful to the translation to identify the System for which the macro was written See Identifying the System when Importing Macros on pace 424 The heart of the Macro Translator is a search and replace algorithm which means that there are some limitations to the inferences it can make Where possible the translator will substitute ATS compatible commands for the existing APWIN commands Using the Macro Translator Figure 299 Importing an APWIN macro procedure Append Import Apwin Macro be The ATS 2 Macro Translator appears as an additional menu selection in the ATS File menu Choose File gt Import gt APWIN Macro to open a file browser for translation Navigate to the appropriate folder and select the macro file you want to translate ATS 2 User s Manual 423 Appendix F Test and Macro Translators The Macro Translator 424 Look ir E Procedures amples E ex PromptStopsDoLoop apb SethezetRate apb SetindDiglhput apb de SetS witchers apb S2FregChk apb de Shell xample apb SeLevelCheck apb de TtFileQutput apb Sete rrorkdode apb Seth ptionF iter apb ne a File name Sets witchers apb Files of type s ystem Two Cascade Files apb Lancel Sustem Two Cascade Pilez apb ve Sistem Two Files apb b System
462. t in an integer number of steps ATS will round the calculated value of steps to the next lower integer value to maintain the exact step size you have entered ATS then takes care of the remainder by adding a final smaller step to the Stop value Logarithmic Scale Steps When using a logarithmic scale the field which had been called Stepsize in Lin mode is renamed Multiply You can set the step size by entering the number of steps in the Steps field just like the Lin setting Or you can enter a value in the Multiply field and ATS will calculate the cor rect number of steps to produce this step to step multiplier If the value you enter does not result in an integer number of steps ATS will round the calculated value of steps to the next lower integer value to maintain the exact step to step multiplier you have entered and then takes care of the remainder by adding a final smaller step to the Stop value X Axis Divisions In Lin mode if Auto is checked the arid lines are selected automatically based on the Source 1 settings If Auto is not checked you can specify a number of arid lines by entering a value into the Div field In Log mode the placement of arid lines for the graph X axis divisions is pre determined and the Div field and the Auto checkbox are not avail able Data 1 As mentioned before every sweep must have at least one sweep Source and one set of Data results The Data 1 area on the Sweep panel is where you select
463. t no user filter files are selected To choose your filters click the browser button to the right of the Fltr field A file browser opens that enables you to select filter files for any of the three filter types low pass high pass and weighting You can also view the filter Info string for any of the three selected filters ATS 2 User s Manual 147 Chapter 10 The Audio Analyzer The Function Meters User Downloadable Filters HP Filter LP Filter Ew None El None El Weighting Filter F ltr None Filter Info OF Cancel Figure 122 The Audio Analyzer User Filter file browser When you have chosen downloadable filters and closed the browser no tice that the BW and Fltr fields have been automatically set to User to re flect your choices As long as you do not exit the ATS control software or load a test file these downloadable filter files will remain attached to their filter lists You still have the option however of choosing other ATS pro vided filters or None from the lists without losing the link to the file you have selected A test saved with an attached user filter will re attach the filter to the Au dio Analyzer when the test is loaded If you select User from any of the three filter lists and a user filter file has not been previously selected for that setting the user filter file browser will appear and prompt you to choose a filter file User filter files created to a number of specifications are
464. t your page settings by restoring these defaults by loading the settings from the current graph screen display or by loading the page settings from a previously saved ATS test file Figure 261 Page Setup Display Layout Trace panel Trace page PF Track Display Changes Color Line Style Thick Data Cyan Solid 2 Analyzer Level A J veld Solid 2 Analyzer Level B Preview Cancel The Trace page shown in Figure 261 gives you the ability to choose which traces will be visible in the printed graph An X on a trace row se lects that trace to be visible You can also specify trace color line style and thickness If you check the Track Display Changes checkbox the trace settings on this page will be unavailable and instead the printer trace settings will be set to the trace settings on the screen display graph Print Setup Click File gt Print Setup to change your printer or access your printer s configuration settings You can also do this from the Print dialog box Printing a Graph Click File gt Print gt Graph to send an ATS graph to the printer If you have not yet set up your page layout you should first go to File gt Page Setup see page 330 ATS 2 User s Manual 331 Chapter 20 Printing and Exporting Printing ATS Data as a Table 332 The Print dialog box will appear Click OK to print the graph or first set other parameters such as number of pages page range printer selection an
465. ta mapped to the Data 1 or Data 2 coordinates Optimize Individually sets the left Y axis calibration for the best display of the Data 1 set of values and sets the right Y axis calibration for the best display of the Data 2 set of values m Optimize Together This option is only available if both Y axes are in use displaying data mapped to Data 1 or Data 2 and which use the same unit domains Optimize Together sets both the left and right Y axis and calibration for the best display of the entire range of values This feature provides the ability to graphically compare traces of the same unit domain plotted against both left and right Y axes m Optimize Left Only This option is only available if the left Y axis displaying Data 1 and other data plotted against the Data 1 axis is in use Optimize Left Only sets the left Y axis calibration for the best display of the Data 1 set of values a Optimize Right Only This option is only available if the right Y axis displaying Data 2 and other data plotted against the Data 2 axis is in use Optimize 288 ATS 2 User s Manual The Graph Options Menu Chapter 16 Graphs Right Only sets the right Y axis calibration for the best display of the Data 2 set of values Unlike the Zoom features the Optimize options do not issue a Sweep Reprocess Data command to the DSP for batch mode FFT measure ments Optimize only operates on the graph display and does not plot new data There is no need to r
466. te Table checkboxes on the ex panded Sweep panel to choose the sweep display mode When you run a sweep you will be able to view the data entering your display in real time The tabular display is shown in the ATS Data Editor panel see page 307 If you have made a sweep without Create Table set you can still E choose to view the data in the Data Editor which is opened by clicking the Data Editor button or by using the Menu command Panel gt Data Edi tor When using a graph for display you are limited to two sets of unit choices Volts dBr etc for your data results since ATS can use only the left and right Y axes to calibrate data values However in tabular form this constraint does not exist and you can specify different units and measure ment domains for each of the Data 1 through Data 6 columns if you wish If you are running sweeps in an automated or manufacturing test situation where speed is most important you can set both sweep display modes OFF for fastest performance ATS 2 User s Manual 265 Chapter 15 Sweeps and Sweep Settling Go Stop Pause 266 Go Stop Pause Once you have your Source and Data settings made all that remains is to start the sweep Simply click the Go button on the Sweep panel or the toolbar you can also start the sweep by selecting Sweep gt Start from the Menu bar or by pressing function key F9 To stop the sweep click the Stop button on the Sweep panel or the toolbar you ca
467. te and display batch mode DSP measurements Although these are unlike real time sweeps in that there is not a swept generator signal or discrete channels of resultant data to be graphed batch mode measurements are similar from an operational point of view and in the graphical requirements for an X Y type plot with scaled and calibrated axes Batch mode sweeps are selected by choosing the Spectrum Analyzer the Digital Interface Analyzer or the Multitone Audio Analzyer in the Sweep Source and Data instrument browsers This chapter focuses on real time sweeps For setup and operation of the Sweep panel in batch mode measurements see the material in The Spectrum Analyzer Chapter 11 The Digital Interface Analyzer Chapter 12 and The Multitone Audio Analyzer Chapter 13 There are a few Sweep controls Transform Data w o Acquire Reprocess Data and Spectrum lt gt Waveform which affect only batch mode measurements The operation of these controls is briefly mentioned in this chapter and explained in more detail in the specific Analyzer chapters Plan Your Sweep When you begin a sweep a list of questions like these can help you de velop an effective test strategy m What parameter will the test sweep In other words what is the independent variable m Over what range m What data results do I want to see That is what will the dependent variables be m What range do I expect the results to cover m How many points of data do I
468. termined 2 by Latest Point 16 5th 4th 3rd 2nd Preceding Preceding Preceding Preceding Preceding Latest Point Point Point Point Point Point Figure 222 Successfully settled reading using Exponential method where Tolerance is set to 1 and Points is set to 5 To satisfy the Exponential criteria a measurement N must agree with the immediately preceding measurement N 1 within the Tolerance ATS 2 User s Manual 281 Chapter 15 Sweeps and Sweep Settling Sweep Settling 282 value and must also agree with measurement N 2 within twice the Tol erance value and with measurement N 3 within four times the Toler ance value and so on This relationship must hold for the number of consecutive measurements set in the Points field Figure 222 shows a se ries of points which have fallen within the specified Exponential settling criteria envelope Flat Settling Algorithm The Flat Algorithm reports a data point when these two conditions are met m The signal is so stable that the difference between any two consecutive readings expressed as a percentage is less than the percentage value specified in the Tolerance field m This degree of stability is held through the number of readings specified in the Points field The settling criteria envelope for the Flat algorithm is a pair of horizon tal lines at the plus and minus tolerance percentage values The gray lines on Figure 222 illustrate the Flat envelope for a
469. th The two results of an FFT consist of amplitude and phase values for a number of frequencies The number of frequencies is half the number of samples in the FFT record length An FFT length of 8 samples would divide the range from DC to half the sample rate into 4 rather wide bands which are called bins and provide the amplitude and phase values for each of the bins For more resolution a greater FFT length is required An FFT length of 16 384 samples would result in 8 192 bins across the same frequency range The bin width also called line spacing is an expression of the frequency resolution of the FFT and has this relationship to sample rate and record length Sample Rate Bin Width _ _ Record Length With an FFT length of 16 384 samples at a sample rate of 48 kHz the bandwidth of the FFT would be OWA oni The bin width would be If a frequency domain amplitude graph were plotted it would span the range from O Hz to 24 kHz and have 8 192 bins each 2 93 Hz wide The amplitude of the energy falling within each bin would be plotted A spec trum graph of a 800 Hz squarewave made with these settings would look like this Figure 290 FFT spectrum of 800 Hz squarewave using the Equiripple window ATS 2 User s Manual 395 Appendix C FFTs 396 FFT Record Looping In this FFT you can clearly see the 800 Hz fundamental followed by the series of odd harmonics
470. th respect to the Freq value entered in the References Freq field lower on the panel For specific definitions of these relative frequency units see the Frequency Units dis cussion on page 372 Meter Ranging Practical devices have an optimum amplitude operating range in which they exhibit their best performance ATS 2 gives you the choice of auto matic ranging or autoranging or manually setting a fixed maximum range Ranging is controlled independently at two different points within the Audio Analyzer instrument as shown on Figure 101 The upper set of Ranging controls acts on the A and B signals applied to the Level meters and Frequency meter displays The lower set of Ranging controls acts on the two channels of the Function meter There is an additional set of ranging circuits in the analog input circuits controlled from the Analog Input panel discussed on page 47 If you are using the analog input to the Audio Analyzer these ranging controls will also affect your measurement Autoranging The Audio Analyzer is normally operated with automatic ranging indi cated by a check mark in each of the appropriate Range check boxes This provides operation with no possibility of clipping due to high ampli tude signals Click the Range check box to defeat autoranging The range setting field for that meter and channel will become active and you can enter a fixed maximum range for that input Fixed Range Using a fixed range pro
471. th the Function meter reading fields The Function meter ranging controls operate in exactly the same man ner as the Level meter ranging controls which are discussed in detail on page 129 ATS 2 User s Manual The Function Meters Chapter 10 The Audio Analyzer Detector Type Figure 117 The Audio Analyzer Det ata ETE z BP BR Fltr Freq Detector selections g oeme Sweep Teak References dBra f387 3 rei dBr B 387 3 mi a Freq 00000 kHz wiFS I O00 4 watts 8 000 Ohms dBm 800 0 Ohms The right hand field following the Det label permits selection of detec tor type for the Function meter of the Audio Analyzer The available selec tions are RMS Fast RMS and Quasi Peak Note These choices also affect the Level meters When either rms detector is selected for the Function meters the Level meters use the same type of detection When Quasi Peak is selected for the Function meters the Level meters use normal RMS detection Detectors and Crest Factor 3 5000 VDC is always 3 5000 VDC But AC voltages by definition are always changing We must agree to measure AC including audio signals in a way that is consistent and appropriate for the use at hand Historically AC was simply rectified with a diode a detector in radio terms for measurement But what kind of a detector Half wave Full wave How quickly should our detector respond How long do we gather signal before we report the voltage As time went o
472. th this maximum value including data points which may be out side the range you set for examining the data Figure 256 Compute Maximum Dialog Box jks 0 0000 Hz 0 0000 kHz ATS 2 User s Manual 325 Chapter 19 Performing Computations on Data Compute Equalize 326 Compute Equalize Compute Equalize shifts the value of each point in the selected data set by the value at the corresponding point in the EQ Source data set This gives a result similar to attaching an EQ file to the Analog or Digital Generator see Attaching an EQ Curve page 87 however the Com pute Equalize technique allows you to apply an EQ curve to your mea surement after the fact rather than equalizing the swept tone Figure 257 Compute golwe gi Equalize Dialog Box Data to Compute Eq Curve Source Column Apply After Sweep I Data 1 Data 2 FP Data 3 T Data 4 Data 5 Data 6 r EN Source Mone F El Cancel Close Compute Compute And close Compute Equalize can use either a data column from an attached EQ file or a data column from the current data in memory as an EQ source Select the EQ Source using the browser in the Compute Equalize di alog box The list under EQ Source initially contains two choices None and SweepData To use a data file click the browser button and navigate to the file If you want use data from another column of the current data in mem ory select SweepData from the EQ Source list In
473. the Transform buffer Operation From the Main menu select File gt Import gt wav File You will be presented with the File Open dialog Browse to the file you would like to import Click Open to continue In a few moments you will be presented with the Import MS wav Waveform dialog In the Instrument Destination area select the memory buffer where the audio data will be stored the Arbrtrary Waveform buffer for the Analog or Digital Generator the Acquisition buffer or the Transform buffer If there is currently data in the Arbitrary Waveform buffer the Update current gener ator file checkbox will be available and you must check the box to over write the current data ts Import MS wav Waveform Eg Instrument Destination Analog Generator Digital Generator Acquisition 5 Transform Update generator file From 1t Waveform in File From nd Waveform in File Ch1 Ch 1 O Ch 2 Ch2 O None Truncate waveform beginning Sec O Samples o ATS 2 User s Manual 411 Appendix E AP Waveform File Support MATLAB support 412 Stereo WAV files contain two audio waveforms the first for the left chan nel and the second for the right channel You can direct these waveforms to the buffer memory channels using the buttons in the From 1st Wave form in File and From 2nd Wavefrom in File areas If you are importing a mono WAV file the 2nd Waveform in File options are not ava
474. the first Channel Status Block Preamble transmitted or received The Receive Block trigger is delayed by two full frames by the AES receiver The Jitter Generator signal triggers at every cycle of the sinewave signal generated by the DIO jitter generator This selection provides a stable dis play of the received jitter waveform when measuring through a digital de vice Triggering for squarewave acquisitions None of the serial digital interface trigger sources receive and transmit block error and sub frame sources is useful when measuring squarewave jitter For stable triggering on a squarewave signal split the connection with a BNC T adapter and connect the two resultant lines to the ATS 2 DIGITAL INPUT and the TRIG IN rear panel connection Select Trig In Ext as the Trigger Source The Jitter Generator trigger selection works only when AES3 Jitter on the DIO panel is turned on This trigger mode can be useful when looking at jitter on a squarewave clock that is derived from an AESS signal fed from ATS 2 s digital generator output Trigger Slope Figure 169 Digital Interface Analyzer Trigger Slope t Pos Neg Trigger Slope amp Data Acquisition buttons Pata Acquisition Posttrig Pre tig The Trigger Slope buttons allow you to select whether the Digital Inter face Analyzer acquisition triggers on the positive going rising or nega tive going falling slope of the trigger waveform selected in the Source f
475. the same data column can be used as a limit for multiple measurements If you have checked the Stereo Sweep checkbox on the Sweep panel the limit attached to Data 1 will also be at tached to Data 3 See Stereo Sweeps page 267 Attaching a Limit File Limits are attached to specific data traces on a sweep To attach a limit file choose the data in your sweep that you would like to compare to a limit Data 1 for example and click the Limit button for that Data The Limit File Attachment dialog box will appear Browse to the data file that contains the limit data you would like to use You can select any type ATS 2 User s Manual Setting Limits Chapter 18 Editing Data and Setting Limits of AP data file not just an atsl Limit file as the source of your limit val ues Figure 243 Limit File Attachment dialog box Upper Limit File ars 2 Limit Test atsl El Column Prato A d Edit Upper Limit es Limit File ars 2 Limit Test atel Column Analyzer Level A Edit Lower Limit F Terminate Sweep on Failure You can attach upper limits lower limits or both Just select a data file in the appropriate area of the dialog box Check the box labeled Upper and Lower Limit are from same file if you are using data from a single file for both upper and lower limits Once you attach a data file a list of the available data columns in the file will be displayed in the list box under the file selection field
476. the source and termination impedances will cause the values of dBu and dBm to diverge In other impedances the values will not be equivalent even at the zero level Unless you know the circuit impedance and have a clear reason to use the dBm reference use dBu dBV decibels relative to 1 000 V rms This is usually the correct choice of units for audio levels in consumer audio equipment and systems The dBV is a voltage unit and like the dBu is independent of circuit imped ance When used with the Analog Generator dBV is an open circuit value and the actual output voltage will be less with a load ATS 2 User s Manual 375 Appendix A Units of Measurement Digital Amplitude Units 376 Digital Amplitude Units FS Digital Full Scale All of the units for digital domain audio amplitudes refer to digital full scale In pulse code modulation PCM audio the amplitude of each audio sample is represented as a number The maximum and minimum values of these numbers vary with the digital word length but they are precisely defined A signal which attempts to exceed these values can drive a digital system into overload in a popular expression the signal runs out of numbers Positive Full Scale Negative Full Scale err li Value Value 16 bit FFF Hex 8000 Hex 24 bit 7FFFFF Hex 800000 Hex The Audio Engineering Society defines digital full scale in terms of a sine wave whose peaks just reach the maximum positive and negative
477. the value pro grammed in the Frequency entry field on the Sync Ref panel or outside the amplitude range required for reliable operation The indicator may re quire several seconds to indicate an out of range condition TRIG IN The TRIG IN BNC provides an input for triggering data acquisitions in batch mode Analyzer instruments the Spectrum Analyzer the Multitone Audio Analyzer and the Digital Interface Analyzer The TRIG IN input will accept standard 3 V or 5 V TTL CMOS logic sig nals ATS instruments normally trigger on the rising edge of the signal tran sition although option switches on each instrument panel enable inversion of the trigger function TRIG OUT and the Main Trigger Panel Figure 271 The Main Trigger panel Main Trigger Pa Source Rev Error g W Confidence W Lock M Coding The ATS 2 trigger output signal appears at the TRIG OUT BNC connec tor on the rear panel This signal is intended to trigger an oscilloscope or other monitoring device at the occurrence of a specific condition in the course of measurement The source for the trigger output signal is selected on the Main Trigger panel These selections are identical to the trigger choices on the Digital In terface Analyzer panel see page 209 Both panels control the same func tions interactively The Trigger Output is a 5 V TTL CMOS logic signal with a 50 Q source impedance The rising edge of the trigger output signal corresponds to the
478. ting parameters in an interrelated manner You can use nested sweeps to generate a set of frequency response curves made at a number of different amplitudes for example or you can graph overlaid response measurements for a multichannel recorder using an Audio Precision switcher under ATS 2 control The nested sweep feature is enabled by entering settings into Source 2 In a nested sweep Source 1 is still used as the primary independent variable When the sweep starts ATS looks first to Source 2 for the initial Start setting then begins the first Source 1 sweep When that is com pleted ATS then increments by one Source 2 step Then the Source 1 sweep is made again This process is repeated until all the steps defined in Source 2 have been completed The X axis scaling and calibration are taken from the Source 1 settings The Source 2 parameter values are not directly visible on the graph but these values are displayed in the Graph Legend see page 295 The Source 1 and Source 2 controls and browser operate identically Pre Sweep Delay The pre sweep delay setting enables you to specify a time delay be tween the Go command and the actual beginning of the sweep to allow for stabilization of the generator or the device under test if necessary This can help eliminate transient glitches at the start of a sweep The allow able pre sweep delay range is 0 000 seconds to 4 000 seconds the default setting is 200 ms The pre swe
479. titone eee stimulus spectra F1 F2 F3 F4 F5 F6 F7 F8 F9 F40 F11 F12 CHANNEL B Fi F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F42 We will look at different types of multitone measurements in the next sec tions for our example diagrams we will assume the use of the multitone stimulus signal diagramed in Figure 174 This multitone example has ten tones on Channel A and ten on Channel B For crosstalk measurements two tones on each channel are unique F9 and F11 on Channel A and F10 and F12 on Channel B The number and approximate frequencies of the tones in a multitone waveform are determined by the type of test you are performing If you are making a 1 3 octave spectrum analysis for example you would choose 31 tones each very near to one of the frequencies specified for the standard ISO 31 test The exact frequencies selected for the 31 tones must each be synchro nous for the record length of the FFT This is accomplished by making each tone an integer multiple of a base frequency which is synchronous Sample multitone waveforms In ATS 2 multitone waveforms are generated using the Arbitrary Wave form function in either generator which loads and plays a waveform file ATS 2 User s Manual 215 Chapter 13 The Multitone Audio Analyzer Overview Multitone Testing from disk Many multitone waveform files such as ISO 31 are included with ATS 2 ready to load and use Creating custom multitone waveforms You
480. to 1 mW and the audio circuits of the day often had an impedance of 600 Q The voltage drop across a 600 Q re sistor dissipating 1 mW is 0 7746 V and this voltage which reads 0 dBm on a dBm meter across 600 Q came to be regarded as zero level in professional audio circles However most audio circuits do not have a 600 Q impedance Mi crophone circuits may be 150 Q and headphone circuits may be 8 Q This is even more the case in modern design where circuit outputs of ten have very low impedances from perhaps 10 Q to around 100 Q and input circuits often are bridging with impedances of 10 000 Q or even 100 000 Q A milliwatt dissipated in any of these circuits will not read 0 7746 V and the dBm meter which is simply a voltmeter cali brated for a 600 Q circuit will be in error The circuit impedance must always be taken into account in power measurements Because of this the dBm can be misleading It has fallen out of use in the last 20 years except for specific applications where power trans fer is an important consideration and the circuit impedances are known and its place in professional audio has largely been taken by the dBu where the u can be taken to mean unloaded The dBu is a valid level measurement in audio circuits of any impedance The value of 0 dBu 0 7746 V rms is the same voltage as O dBm in a 600 Q circuit in 600 Q O dBu 0 dBm However at other levels the voltage divider formed by
481. to ATS 2 could degrade the system performance However you may use the balanced input of one channel and the unbalanced input of the other channel at the same time Bal DC Unbal Couple Figure 10 Analog Input Circuit Configurations The Digital Output The digital output signal is available as a balanced electrical signal at the XLR male connectors in either single or dual connector configurations This output satisfies the electrical requirements of the AES3 professional in terface standard Use the connector labeled I for the customary sin gle connector configuration and both Il and Il for the optional dual connector configuration The output signal is also available as an unbalanced electrical signal at the BNC connector This output satisfies the electrical requirements of both the AES3id professional standard and the IEC60958 3 standard which is compatible with the S PDIF consumer digital interface format The XLR and BNC digital outputs are calibrated with the assumption that the signal is terminated in the proper impedance 110 Q for the bal anced output 75 Q for the unbalanced If the signal isn t properly termi nated the actual output voltage will be different from the voltage specified in the DIO panel The digital output is also provided as an optical signal compatible with the Toslink interface Digital output selection and interface configuration are set on the DIO panel page 5
482. trigger event ATS 2 User s Manual 345 Chapter 22 Sync Ref Trigger and Aux 346 Figure 272 The Main Trigger source list Main Trigger Al Ea S OMI Analog Gen ChE Rew Sub Frame Ch Rev Sub Frame Celit ChE Rew Sub Frame Celit Rev Block 192 frames Ac Error Ch mit Sub Frame CHE mit Sub Frame Ch mit Sub Frame Delit CAB mit Sub Frame Delikt mit Block 192 frames Ch Sync Aet Aey Sub Frame ChB Sunc Ref Acy Sub Frame Sync Ret Row Block 192 frames Sync Ret Aew Error The Trigger Output sources are m Analog Gen A trigger transition is generated for each cycle of the current Analog Generator waveform Digital Gen A trigger transition is generated for each cycle of the current Digital Generator waveform m Jitter Gen A trigger transition is generated for each cycle of the current Jitter Generator waveform u Trig In Ext A trigger transition is generated for each external trigger transition received at the TRIG IN BNC connector a Line Mains A trigger transition is generated for each cycle of the AC mains line voltage ChA Kcv Sub Frame A trigger transition is generated at the beginning of each Channel A subframe each X preamble plus each Z preamble in the interface signal received at the digital input If there is jitter in the received waveform that jitter will be reflected in the trigger waveform ChB Rcv Sub Frame A trigger transition is generated at the beginning of e
483. trum Analyzer panel are sufficient to cause each acquisi tion to start at the same relative point on the waveform choose one of the synchronous selections that do not re align The sync without re align op tions require less digital signal processing and are faster Sync re align For some signals re alignment may be necessary for synchronous aver aging Choose one of the Sync re align options to select this technique With re align signal is first acquired with any triggering selection includ ing Free running which is untriggered The DSP then slides the signal forward or backward in time until it is aligned with the sum of already accu mulated signals The final averaged result will start at the value set in the Delay field and continue from that point for the Length value Any signal before and after is erased For example if 8192 is selected in the FFT field and 100 ms is entered in the Delay field assuming that the Acquire field value is sufficiently long to contain 100 ms plus 8192 samples the final averaged result will start at 100 ms and continue for a bit more than 8192 samples beyond that point to approximately 271 ms at a 48 kHz sample rate A time do main view or an FFT may then be made anywhere within that 8192 sam ples An FFT of a synchronously sampled signal will be correct only if the sig nal transformed as determined by FFT Start Time and Length lies com pletely within the occupied portio
484. trument Source area select the memory buffer that contains the audio data to be exported Only memory buffers that contain audio data will be available If you select the Transform buffer you can force the length of your exported audio data to match the current record length set ATS 2 User s Manual 409 Appendix E AP Waveform File Support Exporting to WAV ES Export MS wav Waveform Instrument Source Analog Generator Select the data source for Digital Generator the exported waveform Acquisition Transhorm Left Waveform Right Waveform 2 Ch 1 O Ch 1 0 Ch 2 Ch2 O None Use instrument defaults Dither Bits None 16 Triangular 2d Rectangular Wavetorm Length sec Samples 5 by the FFT lenath setting by checking the User Instrument defaults checkbox below Stereo WAV files contain two audio waveforms the first for the left chan nel and the second for the right channel You can direct the audio data in the buffer channels to either the Left Waveform or the Right Waveform of the WAV file you are creating If you select None for the Right Waveform a mono WAV file will be created Set your dither preferences in the Dither field Your choices are None Triangular dither or Rectangular dither Set the resoluton word length of your exported WAV file in the Bits field Choose any word length from 8 bits to 24 bits Set the length of your exported waveform in the Waveform Length
485. ts V bit to in valid V bit set high when the tape is not playing and to valid set low when the tape is moving The V bit transmitted by ATS 2 can be set high both Channel A and B are set together by checking Invalid in the DIO Output Send Errors section Jitter Measurement Figure 35 DIO Jitter Measurement gt gt ETE ai Jitter Measurement Jitter alas Status Bits B a 700H2 to 100kH C Pki Avg BOHe to 100kHz 120Hz to 100kH2 PODA to 100kHz 1200H2 to 100kHz The jitter of the digital interface signal is shown in the DIO Panel Jitter Measurement display This measurement is made from the error signal of the AES receiver input phase lock loop and is sensitive to jitter of the total signal including transitions in both the preamble and the data sections of the frames Jitter measurements may be displayed in units of UI unit inter vals or s seconds typically ms or nanoseconds You can choose one of two detector responses Pk peak and Avg av erage for the jitter meter Both detectors are calibrated in terms of the peak value of a sinewave The averaging detector is typically used for making frequency response plots of the jitter signal while the peak detector should be used for charac terizing actual interface jitter Peak jitter measurements will almost always give a higher number than average depending upon the crest factor of the jitter waveform Jitter is often dominated
486. tting the largest positive value in that span Since all sample values are examined no signal peaks can be missed Eye Pattern When Eye Pattern is selected an entirely different sort of processing takes place in the DSP Eye Pattern overlays many one Ul segments of the acquired data on top of one another Following acquisition of the digital interface signal and extraction of an average clock signal from it the worst case nearest to O V amplitude is de termined for each time increment relative to the beginning of each data cell These values are plotted when Intervu Upper Eye Opening and Intervu Lower Eye Opening are selected as Data 1 and Data 3 param eters resulting in a plot of the worst case inside of the eye See page 192 for more information on the eye pattern The Intervu Upper Eye Opening and Intervu Lower Eye Opening selections will not be available in the Data browser unless Eye Pattern is selected in the Wave Display field on the Digital Interface Analyzer panel Conversely if Eye Pattern is selected conventional amplitude vs time displays will not be available Jitter Detection Figure 164 Digital Interface Analyzer panel Jitter Detection Stable Bits Jitter Detection selections A F Stable Bite VETSQES Al Bits Preamble Window Squaremave Alsing Squarewave Falling The Digital Interface Analyzer is capable of measuring jitter both on AES3 IEC60958 interface signals and on simple squarewave clock s
487. ttom values and the graph will re draw itself to correctly plot your results You can also use the Optimize function on the Graph panel to reset the Y axis extents to accommodate your results You can also have ATS automatically set the Top and Bottom values on this panel in response to the Data 1 readings Click the Autoscale checkbox to enable this function Data 1 Log or Lin Scales If neither the Top nor the Bottom value is zero or negative you have the option of calibrating the Data 1 axis on a logarithmic or a linear scale ATS 2 User s Manual Data Limits Chapter 15 Sweeps and Sweep Settling If either value is zero or negative or if decibel units are chosen these are available for amplitude data the Log and Lin option buttons will not be available and the scale will be set to linear Y Axis Divisions In Lin mode if Auto is checked the arid lines are selected automatically based on the Data 1 settings If Auto is not checked you can specify a number of arid lines by entering a value into the Div field In Log mode the placement of arid lines for the graph Y axis divisions is pre determined and the Div field and the Auto checkbox are not avail able These controls affect scaling for real time data acquisition The graph can be rescaled to accommodate the data in the graph buffer memory us ing the graph Optimize function page 288 Data Limits The Limits button opens a dialog box enabling you to attach accep t
488. tude A jitter signal with low average jitter will be represented by a high proba bility of near zero values Signals with high average jitter are represented by values falling into bins farther away from zero Squarewave jitter will tend to produce a strong pair of peaks at the posi tive and negative peak jitter amplitudes with a low amplitude area be tween them Sinewave jitter will also produce a graph with two peaks but the curve between them will follow a gentle arc Random jitter histograms will vary from acquisition to acquisition while jitter dominated by a coher ent signal will tend to be more consistent ih th Bo h mn 1 Figure 160 Digital Interface Analyzer jitter probability As indicated in Figure 151 this view requires these Sweep settings 200 ATS 2 User s Manual InterVuMenu atsb Chapter 12 The Digital Interface Analyzer Source 1 Intervu Jitter and m Data 1 Intervu Probability An initial Source 1 range should be about 50 ns Data 1 should be set on a linear scale with 0 at the bottom and a top value between a few percent up to 50 When comparing histograms to the DIO panel jitter meter remember that the DIO panel meter calibration is in terms of peak or average values while the Digital Interface Analyzer jitter calibration is in terms of rms values InterVuMenu atsb Audio Precision Technical Support have written an AP Basic macro which acts as a simple and powerful front e
489. uced at both the analog and digital generator outputs Special Waveforms Figure 92 Digital Generator Special Digital Generator El Polarity Pass Thru Monotonicity J Test Walking Ones Walking eros Auto On Constant Value To Invert Random f 000 FFS Amplitude 7 Frequency 999999 k Wfm Special Polarity The polarity waveform is designed to be obviously asymmetrical so that it is easily apparent if signal is inverted or not The waveform is the sum of ATS 2 User s Manual 115 Chapter 9 The Digital Generator Choosing a Digital Generator Waveform 116 EE E E o Figure 93 Digital Generator Special 2 Digital Generator O x Polarity wfm Special Polarity Cha F 59700 kHz requency z mi ae Auto On T Track A T Invert j CHE T Invert 1 000 FFS Amplitude 1 000 FFS the fundamental tone set in the Frequency field and its second harmonic in a fixed phase relationship When the output of the DUT is viewed using an oscilloscope or the ATS Spectrum Analyzer in the time domain view the signal will reveal whether or not there has been a polarity inversion in the DUT or in the signal inter connections e Audio Precision Oe x SU0m 500 rn 500u Figure 94 Polarity waveform normal polarity shown The only setting available for the polarity waveform is Frequency Wfm Special Pass Thru The Special Pass Thru selection does not cause a wav
490. ug the macro if necessary Mapping exceptions and substitutions Following is a list of Test and Macro Translation mapping exceptions substitutions and other issues that may need to be addressed by the user Most of the mapping exceptions are the same for both test and macro translation Differences in handling between the two translators are noted within the listing Analog Generator m The Cascade Analog Generator primary waveform selections are mapped to equivalent analog waveforms generated in the digital domain in ATS m MLS is not support by ATS 2 MLS selections are substituted with Sine Normal a Normal Burst Triggered Burst and Gated Burst are not supported by ATS All of these settings are mapped to Shaped Burst which is the closest available waveform a CCIF DFD DIM 30 DIM 100 DIM B IMD waveforms are not supported by ATS These are mapped to SMPTE DIN 1 1 m The Pink noise waveforms are not supported in ATS All Noise and Noise D A waveforms including the true random white noise of the BUR GEN option are mapped to the ATS Noise waveform which is only available as pseudo random white noise m Depending on the options installed certain output impedances may not be supported for ATS 2 balanced outputs In APWIN three balanced output impedances are available 40 Q 50 Q in System One 150 or 200 Q with the EURZ option and 600
491. ument in Data 1 ATS will set up the opposite channel in Data 3 to match Since both of these readings are of the same measurement domain they will both be plotted against the calibration and scaling on the left hand Y axis This leaves Data 2 and the right hand Y axis available for other use If you also set up a channel from a second reading source in Data 2 during a stereo sweep ATS will automatically set up the opposite channel in Data 4 to match m In stereo sweep crosstalk tests ATS performs automatic input and output switching and runs two cross channel measurements in succession The two passes are plotted as separate data in one graph and saved in one file To make a Stereo sweep ATS 2 User s Manual 267 Chapter 15 Sweeps and Sweep Settling Single Point Sweeps 268 m Set up Source 1 and Data 1 and Data 2 if you want to plot two different pairs of variables for your sweep m Click the Stereo checkbox on the Sweep panel Some reading parameter selections such as Phase or DCX 127 DMM Volts are not stereo signals If you select such a parameter for Data 1 or Data 2 the Stereo sweep function will not be available Opposite channel Limit files which have been automatically attached to Data 3 or Data 4 in Stereo sweep can be changed or disabled by click ing the Limits button for that Data function Single Point Sweeps A single point sweep is an ATS sweep in which the independent vari able Source 1 is held
492. urce is called an External Sweep External Sweeps are discussed be ginning on page 263 Selecting a Sweep Source When ATS is first loaded the default sweep source in Source 1 is the Analog Generator frequency To select a different source click on the Source 1 browser button Browser Sweep Source 1 E3 Instrument Parameter Frequency ChA Amplitude Show Readings e Show Settings Figure 215 The Sweep Source 1 browser dialog box A dialog box will open that displays the instruments and parameters available as sweep sources Click on a instrument and you will see the set tings associated with it in the right browser window ATS 2 User s Manual 259 Chapter 15 Sweeps and Sweep Settling Source 1 260 For ordinary sweeps be sure that you have selected your source from the instrument settings list Instrument readings are used for External Sweeps page 263 The check boxes on the browser allow you to choose the settings or readings lists Start and Stop Values The values entered in the Source 1 Start and Stop fields set the sweep range and direction and also become values for the graph X axis end points In a frequency sweep for example the default settings are 20 kHz in the Start field and 20 Hz in the Stop field With these settings the sweep will move downward in frequency from 20 kHz to 20 Hz If you would like your sweep to move upward from low to high enter 20 Hz as the Start value and 20 kH
493. urement from the units drop down list shown in Figure 44 Changing a unit of measurement will not change the audio amplitude only the expression of the value See An alog Amplitude Units pace 372 The value displayed after pressing Enter may differ slightly from the value you typed in since ATS will step to the nearest amplitude increment The Analog Generator will not permit an output amplitude entry greater than 16 Vrms 22 62 Vp when configured for a balanced output or 8 Vrms 11 31 Vp when configured for an unbalanced output If you en ter a value greater than these maximum values or a combination of values in EQ Sine mode for example which results in a greater value an error message is displayed Waveforms other than a sinewave are calibrated in peak equivalent sinewave terms that is the Amplitude setting field is calibrated to show the rms value of a sinewave with same peak value as the waveform se lected Selecting a squarewave with an Amplitude value of 1 000 Vrms on the Analog Generator panel for example produces a 1 414 Vp squarewave signal ATS 2 User s Manual Choosing an Analog Generator Waveform Chapter 8 The Analog Generator Choosing an Analog Generator Waveform The Analog Generator offers a wide choice of test waveforms selectable from the primary and secondary waveform lists Analog Generator MIES Sad Er Sine Y Moral ka Jane Ho E Ch A Figure 45 Analog Generator Primary Waveform Select
494. ut voltage 54 output jitter generation 58 output senderrors 57 Rate Ref 66 Digital interface signal amplitude histogram Digital Interface Analyzer 197 Digital interface signal bit rate histogram Digital Interface Analyzer 199 Digital interface signal pulse width histogram Digital Interface Analyzer 198 Digital interface signal soectrum Digital Interface Analyzer 195 Digital interface signal waveform Digital Interface Analyzer 191 Digital Output connection 38 front panel connectors 32 DIN IMD measurements see IMD measurements 137 DIN IMD waveforms 112 DIO panel see Digital I O panel Display samples FFT display processing 174 DICO iros eae hoe ee 120 Documentation about thismanual 2 Getting Started Manual XIX 5 see Help online 433 Index Domain analog vs digital 5 D to A converter testing monotonicity waveform 118 Dual Connector Mode 53 Dual sine waveforms 105 Dual XLR see also Dual Connector Mode 53 Dual XLR 2XOSR see also Dual Connector Mode 53 E Edit Menu 14 Editing data see data editor 307 PIAS aaa ee ae E A A A 384 EQ Te is ara E ers 310 EQ sine waveforms 107 Equalization generator 87 10
495. utput can be switched indi vidually on and off by the CH A and CH B buttons on either side of the OUTPUTS button Both the main OUTPUTS button and an individual channel button must be switched on to route signal to the digital output cir cuitry Auto On If the Auto On checkbox is checked the Digital Generator is automati cally switched ON when a sweep starts and OFF when the sweep stops This is useful for power amplifier or loudspeaker testing With the genera tor set to OFF and Auto On enabled signal will only be applied to the DUT while the sweep is actually running ATS 2 User s Manual 101 Chapter 9 The Digital Generator The Digital Generator Panel 102 See Chapter 15 for more information on sweeps Also see Pre Sweep Delay on page 269 for a discussion of avoiding transients in the Auto On mode Channel Invert ATS 2 maintains correct absolute polarity throughout the system You can invert the polarity of either audio channel by clicking the Invert checkbox for that channel When neither or both Invert boxes are checked both channels have the same polarity Polarity inversion of one channel with respect to the other can be used to create the stereo difference signal which modulates the subcarrier in some stereo multiplex systems Amplitude Control and Units Figure 73 Setting the Digital Generator Amplitude Auto O W Track A M Invert ra Invert 0 000 dBFS 0 29 Bits 1 000 rmez
496. valent of clicking Go when Append box is checked Alt F9 Sweep and Repeat Starts a new Sweep in repeating mode equivalent of clicking Go when Repeat box is checked F10 Pause Sweep The sweep pause button Toggles a sweep from running to paused and back again ATS 2 User s Manual ATS 2 and GPIB Chapter 2 The ATS Control Software m F12 Kill Outputs The panic button Turns off all generator outputs a Ctrl F12 Revive Killed Outputs Turns on any generator outputs previously turned off by the panic button ATS 2 and GPIB With Option GPIB hardware installed ATS 2 can also be controlled by the industry standard General Purpose Interface Bus GPIB ATS 2 User s Manual 29 Chapter 2 The ATS Control Software ATS 2 and GPIB 30 ATS 2 User s Manual The ATS 2 Hardware There are no controls or displays on the ATS 2 hardware chassis In stead the ATS 2 user interface is through the controls and displays of the ATS control software ATS EXE running on the personal computer con nected to the ATS 2 chassis by the Audio Precision Interface Bus APIB The hardware module Option GPIB brings the General Purpose Inter face Bus GPIB to ATS 2 GPIB is an industry standard interface that en ables ATS 2 to be controlled by a computer running third party or custom designed software Operation with GPIB is not covered in this man ual For both APIB and GPIB use all signal generation and analysis is per fo
497. value is 600 2 dBm is rarely the correct choice of units for audio measurements dBm units are often mistakenly chosen when dBu units should be used See the sidebar dBm versus dBu on page 375 ATS 2 User s Manual 97 Chapter 8 The Analog Generator Analog Generator References 98 ATS 2 User s Manual Chapter 9 The Digital Generator Test Signal Generation in ATS 2 Most audio testing requires that a stimulus signal be applied to the de vice under test DUT At its simplest the stimulus may be just a mid fre quency sinewave at a nominal level a step up would be a sweep of frequencies or the combination of tones used for intermodulation distor tion IMD testing An example of a very complex stimulus is a multitone burst which has many precisely generated frequencies at a range of spe cific levels The signal generation systems in ATS 2 use digital signal processing DSP techniques to create a wide range of stimulus signals Two Audio Signal Generators ATS 2 has two independent audio signal generating systems the Analog Generator which provides signal to the Analog Outputs and the Digital Generator which is the source of the audio embedded in the Digital Out put signal The Analog and Digital generators both produce their signals in DSP and they are similar in operation and in the settings available on their re spective instrument panels The two generators are completely independ ent and can generate different
498. value you can enter on the Input side of the DIO Generally Meas Input Rate will be used as the scaling source so that audio signal frequency measurements follow any changes in sample rate from the source If the actual measured value is unstable you may enter the nominal in coming sample rate in the Rate Ref field and select DIO Rate Ref for sta ble audio frequency scaling The Output Rate selection can be used to measure the frequency shift ing effects of digital processors and sample rate converters The Status Bits selection refers frequency measurements to the nomi nal standard sample rate if in fact the sample rate is actually encoded into the status bits and will be independent of any moment to moment varia tions in the actual received sample rate Rate Ref Figure 31 The DIO Rate Ref entry field Rate Ref 42 0000 kHz Rate Ref is a reference field A sample rate entered here can be se lected as a reference for digital input or output frequency scaling The ac ceptable range for Rate Ref is 28 8 kHz to 216 00 kHz Peak Monitors Figure 32 The DIO Peak Peak Monitors Channel 4 Mode Channel B Monitors e gt ME gt The DIO panel provides the capability to view the peak levels of the em bedded audio signals These meters indicate the digital input levels prior to the application of deemphasis if used The Mode field between the numeric display fields permits selection among four types o
499. ve about 10 of the sample rate Without realignment the random time relationship between the signal itself and ATS 2 s sample clock will cause random misalignment up to 1 2 clock period resulting in partial cancellation that becomes objectionable at high frequencies Re alignment works with interpolated versions of the signal and aligns accu rately producing accurate amplitude measurements even at high frequencies The re align mode works independently on each channel If the two channels carry different frequency signals re align mode must be used The primary disadvantage of the re align mode is the additional time taken by the DSP to do the operation after each acquisition The synchronous averaging with re align m acquires signal according to whatever triggering selections are in use m interpolates the acquired signal between the actual sample values m locates the first positive going zero crossing in the interpolated data m time aligns that with the first zero crossing in the accumulated record and ATS 2 User s Manual 181 Chapter 11 The Spectrum Analyzer References 182 ard m adds the signal from that point onwards into the averaging buffer This process is carried out after each of the series of acquisitions to be averaged resulting in precise time alignment Triggering is not critically important in this mode if the signal is not noisy and the signal repetition rate is relatively high since the necessary
500. veform and will not trigger A setting greater than zero in the Frequency Resolution field broadens the range of acceptance so that Multitone will recognize and trigger from a frequency shifted waveform The maximum value is lim ited to 13 Setting frequency resolution for rss summing Speed variations such as flutter spread the stimulus tones into close groupings of modulation products sidebands For more accurate measure ments the energy in these sidebands must be considered The Frequency Resolution control sets the range of frequencies that are m included in an rss sum at each specified tone in Response and Crosstalk measurement modes or m excluded from the measurement at each specified tone in Distortion and Noise measurement modes A Frequency Resolution setting of 0 returns the amplitude of the bin at the stimulus tone Greater Frequency Resolution settings widen the range to allow inclusion or exclusion of the amplitudes of the close in mod ulation products The maximum widening of resolution is limited to 13 FFT Length Figure 192 Multitone FFT Length Freq Resolution Jo 00000 X selections aay Laila jao El Processing Triggering Trigger Delay Ch B Phas 32768 The Multitone FFT Length field value controls the record length used when signal is acquired or a re transformation is initiated Longer trans form lengths produce greater frequency resolution more bins in the result ing FFT but
501. veforms Figure 62 Analog Generator Special Analog Generator a Waveform Selections wim Specisl y Polity y Frequency 7 00000 k Polarity 92 ATS 2 User s Manual Choosing an Analog Generator Waveform Chapter 8 The Analog Generator Wfm Special Polarity a Analog Generator Figure 63 Analog Generator Special Polarity We Fre Special Polarity ChA F 1 00000 kH requency z Ch B W Track A 1 000 Wire Amplitude The polarity waveform is designed to be obviously asymmetrical so that it is easily apparent if signal is inverted or not The waveform is the sum of the fundamental tone set in the Frequency field and its second harmonic in a fixed phase relationship When the output of the DUT is viewed using an oscilloscope or the ATS Spectrum Analyzer in the time domain view the signal will reveal whether or not there has been a polarity inversion in the DUT or in the signal inter connections The only setting available for the polarity waveform is Frequency e Audio Precision 500m 0 S00m z 500u Figure 64 Polarity waveform normal polarity shown Wfm Special Pass Thru The Special Pass Thru selection does not cause a waveform to be generated instead it converts the digital audio signal connected to the ATS 2 User s Manual 93 Chapter 8 The Analog Generator Configuring the Analog Outputs rear panel SYNC REF IN BNC connector to an analog signal and passe
502. veforms using the ATS 2 Multitone Creation utility On the Main Menu choose Utilities gt Multitone Creation Multitone Creation Utility opening dialog box ATS 2 Multitone Creation x Adjust the following parameters to create the required waveform Waveform Mame Multitone Waveform Length This field defines the number of samples used to create Sample Rate j18000 a of the multitone Margin Headroom fi FF Create Sweep Table 4755 file PF Create MS RIFF 1420 file Minimize Crest Factor a This field defines the number IY Create Stereo LAGS Waveform of samples created for one channel in the output file Stereo Waveform Amplitude that may contain multiple f Make both equal 1024 iterations of the multitone Optimize individually for Headroom Ale waveform Use Existing File Data Cancel File Options Figure 198 ATS 2 Multitone Creation Utility opening dialog box Figure 198 shows the opening dialog box for the Multitone Creation Util ity The key options are m Waveform Name This is the filename you choose for your multitone waveform and for all the associated files created by the utility The filename extension s will be chosen according the file options you choose in other dialogs Sample Rate Set the sample rate of your multitone waveform to any rate between 28 8 kHz and 108 kHz or set it to 131 072 kHz a Margin Headroom Margin Headroom specifies in decibels the difference
503. vi ATS 2 User s Manual Mapping Two Analyzers into One Analyzer 421 Attached file considerations 422 Reporting Test Translation Exceptions 422 The Macro Translator lt a sb er bk eee GH eee Se a 422 Using the Macro Translator 423 Identifying the System when Importing Macros 424 Macro Translator issues sachs bd eee ee eee wR Se So 424 Numbers OF Constants nese ceed beens eva wes 425 Libraries and the With Command 425 Referenced Files sara rra ene AS ee ae ee 425 Unavailable Features o 425 Reporting Macro Translation Exceptions 425 Mapping exceptions and substitutions 426 Analog Generator 0 0 020008 426 Digital Generator edna SH GEO HSS GS RHE RG EOS 427 Audio INDUL os oud eee ead oe Bae De eee ees 427 Analyzer Settings gan ew tev eh ewe een eee ke ads 428 DIGO Srs seso esa 430 Compute Functions gt gt pan renos anos 430 ATS 2 User s Manual xvii xviii ATS 2 User s Manual Safety Information Do NOT service or repair this product unless properly qualified Ser vicing should be performed only by a qualified technician or an authorized Audio Precision distributor Do NOT defeat the safety ground connection This product is designed to operate only from a 50 60 Hz AC power source 250 V rms maximum with an approved three conductor power cord and safety groundin
504. vide su perior frequency resolution compared to the Digital Interface Analyzer Jitter signal analysis using the Spectrum Analyzer is discussed in Chapter 11 Calibration for Digital Interface Analyzer jitter measurements is in terms of rms values contrasting with the peak or average values selectable for the DIO panel jitter meter The DIO panel jitter generator is calibrated in peak values 196 ATS 2 User s Manual Digital Interface Analyzer Histograms Chapter 12 The Digital Interface Analyzer Digital Interface Analyzer Histograms A histogram is a statistical view showing the probability of occurrence of a set of events throughout a range of possibilities Here s an example the interface waveform nominally moves across a 5 Vpp range with very quick transitions The probability of the instanta neous voltage being either 2 5 V or 2 5 V is high and all other voltages have a low probability The interface amplitude histogram shown in Figure 157 displays these probabilities Interface Amplitude Histogram The interface amplitude histogram view shows a graph of the probabil ity of the interface signal being at particular points across a range of ampli tudes When characterizing the squareness of a digital signal it is often convenient to view a histogram of the signal amplitude With no impairment of the interface signal the resulting histogram will consist essentially of two vertical spikes One is located at approximately
505. w amplitude digital domain signals When the signal frequency is low compared to the sample rate Display Samples will produce an acceptable representation of the original signal ATS 2 User s Manual Display Processing Chapter 11 The Spectrum Analyzer waveform At high signal frequencies the waveform may be entirely unrec ognizable because of graphic aliasing see page 176 in such a case the Interpolation mode should normally be used Peak Values When Peak Values is selected the DSP searches all sample amplitudes in the acquisition buffer between each pair of X axis time values plotted and sends to the computer for plotting the largest positive value in that span Since all sample values are examined no signal peaks can be missed Absolute Values When Absolute Values mode is selected the DSP searches all sample amplitudes in each plotted point to plotted point span as it does in Peak Values mode but takes the absolute value of the largest positive or nega tive value always sending a positive number to the computer Logarithms may be computed when all the numbers involved are posi tive so Absolute Values mode brings the advantage that decibel units may be used on the Y axis to display the waveform Waveform display with Absolute Values mode can create a wide dy namic range oscilloscope view that displays the envelope of an audio sig nal calibrated in units such as dBV dBu and so on Absolute Values mode is mo
506. w to ATS 2 you might want to start with the Quick Guides in Getting Started with ATS 2 which will introduce you to Spectrum Analyzer features See Appendix C for a conceptual overview of FFTs Loading the Spectrum Analyzer ja Analyzer Instrument FFT Spectrum Analyzer Ch A Inp Audio Analyzer e Figure 128 Loading the Spectrum Analyzer INTER Digital Interface Analyzer FASTTEST Multitone Audio Analyzer FFT 8132 Harmonic Distortion Analyzer To use the Spectrum Analyzer first open the Analyzer panel The Ana lyzer panel is a command selection on the Panel menu and is also avail naa able by the keyboard shortcut Ctrl Y or by clicking the Analyzer icon on the Toolbar Now select FFT Spectrum Analyzer from the list on the Analyzer panel This loads the Spectrum Analyzer program into DSP Signal Inputs Figure 129 Spectrum Analyzer panel Analyzer OF x inputs Instrument FFT Spectrum Analyzer y Ch Analog CHB Jitterf11 FFT 8192 Ch Analog ChE Jitter s The Input field of the Spectrum Analyzer offers four signal input se lections a Digital 156 ATS 2 User s Manual Peak Level Monitors Chapter 11 The Spectrum Analyzer Analog These two choices access the signals routed from the Digital Input Output DIO panel or the Analog Input panel respectively m ChA Analog ChB Jitter UI m ChA Analog ChB Jitter s These two choices apply the Channel A signal from
507. we ee ew So 185 aas TIS 2 ee ee oe eS ee a 185 Absolute values FFT display processing 175 AC coupling 127 also see coupling Acquisition waveform file Digital Interface Analyzer 212 Multitone amp Spectrum Analyzer combining mono to stereo 185 235 compatibility en adn 185 235 Opening 4 Yoda ee oe 4 ow eS 185 235 SAVING a 8 re Ge Se Bw 184 234 see Analog to digital converter 41 o AA 6 bao ee ae ee ee ee 24 AES EBU o wa ses be AAA 384 ARES sedes penas aaa ee 384 all ie one eee s armadas ae 401 dioses o arar osease 401 NW sorna eee nen he 401 AGen track tuned filter see bandpass bandreject filter 150 agm IRTE 239 9S TG 64 4 46 b eee eS Ge eS 239 AEW lt p eb AROS Oe ee 55 64 also see y Law Alogrithm 58 110 AAA 280 Amplitude control Analog Generator 80 Digital Generator 102 Amplitude measurements Audio Analyzer 131 Amplitude units 80 102 Analog amplitude units 372 Analog Generator overview 2 2 004 77 ATS 2 User s Manual Analog Input panel converter and sample rate selection 48 DC coupling 47 inputranging 47 overview 24 45 peak monitors 46 source selection 45 Analog Inputs diagram amp description 37 front panel connectors 32 Analog Outputs conf
508. where APWIN commands used numbers If the imple mentation is a simple assignment or comparison such as APAnlr ChAlnput 0 then the translator can make the proper substitu tion e g ATS2 AnalogIn Source apbChA apbAnalogInXLR_Bal aaa However the user may have assigned a variable to the number and then used the variable in the assignment or comparison In these situations the translator has no way of knowing where the assignment may have been made or the number calculated so user intervention is required to rework the code These situations are flagged with a comment indicating that the command has been changed to use constants instead of numbers Libraries and the With Command There are some potential problems in using the With command Some commands though equivalent have been repartitioned into different li braries so a different With command would be required to precede them The translator will take its best guess at the appropriate string for the With command and will flag it with a comment Some may need to be changed to reference a different library and in some cases multiple With commands may be needed Referenced Files As the Macro Translator finds commands in the imported procedure that reference an external file whose extension must change between APWIN and ATS it will copy the referenced file with the same name and path but with the new ATS filename extension and modify the macr
509. x Controlinput 348 Aux Control output 348 Auxiliary bits digital audio signal 385 Auxiliary Control In and Out rear panel connectors 34 Average Compute algorithm 324 Averaging Digital Interface Analyzer 207 Averaging Spectrum Analyzer 167 power spectrum averaging 172 synchronous averaging 168 A weighting filter see weighting filter 146 B bad invalid data flag see Data Editor invalid data flag 309 Bandpass measurements Audio Analyzer 136 Bandpass Bandject filter 149 Bandwidth limitations Harmonic Dist Analyzer 249 Bandwidth filter 144 Bandwidth FFT 394 Bar graph overview 303 to display readings 305 to make settings 306 Basic language 351 Batch mode measurements 257 Batch mode vs real time measurements 43 595 Bin Width FFT 395 Bi phase mark encoding 385 Blackman Harris FFT window Digital Interface Analyzer 207 Spectrum Analyzer 163 Block diagram systeM osado ee DRS 4 Bottom values sweep data 262 432 BP BR filter see bandpass bandreject filter 149 Buffer graph 294 BW see bandwidth filter 144 COM osease 386 CCIR weighting filter see weighting filter
510. y of dBm measurements 600 Q is the default impedance for the dBm reference dBm is rarely the correct choice of units for audio measurements dBm units are often mistakenly chosen when dBu units should be used See the sidebar dBm versus dBu on page 375 Analyzer Digital References Figure 126 Analyzer References Digital References dBr A 100 0 mFFS dBr B f100 0 mFFS Freg 1 00000 kHz WAFS 1 000 Y dBr A and dBr B When the Analyzer Input is set to Digital the dBr A and dBr B ATS 2 User s Manual References Chapter 10 The Audio Analyzer values serve as the digital references for the dBr A and dBr B units selectable at any meter measuring amplitude m Freq The frequency Freq value serves as the reference for the relative frequency units octs decs Hz etc of Analyzer frequency meters a V FS In some setups when ATS 2 is measuring a signal in one domain digital or analog you may find it more convenient to enter or view the equivalent of the signal in the other domain The V FS volts for full scale value is the analog to digital scaling value When testing an external ADC for example enter the value of analog input voltage that produces digital full scale output into this field Then you can select amplitude meter units as V Vp Vpp dBu or dBV to express the measured digital amplitude in terms of the analog input value to the converter In the same way the dBr A and dBr B reference values may also b
511. y to make the change Dual Connector Mode and Status Bits In single connector mode Channel A and Channel B status bits corre sponding to the A and B subframes in the data stream can be set and read In dual connector mode the Channel A labels on the Status Bits panel refer to the Connector I signal and the Channel B labels refer to the Con nector II signal In this mode the received status bits are read from subframe A on each of the two signals subframe B status bits are ignored Transmitted status bits in dual connector mode are identical in both subframes ATS 2 User s Manual 75 Chapter 7 The Digital I O Panel The Status Bits panel 76 ATS 2 User s Manual Chapter 3 The Analog Generator Test Signal Generation in ATS 2 Most audio testing requires that a stimulus signal be applied to the de vice under test DUT At its simplest the stimulus may be just a mid fre quency sinewave at a nominal level a step up would be a sweep of frequencies or the combination of tones used for intermodulation distor tion IMD testing An example of a very complex stimulus is a multitone burst which has many precisely generated frequencies at a range of spe cific levels The signal generation systems in ATS 2 use digital signal processing DSP techniques to create a wide range of stimulus signals Two Audio Signal Generators ATS 2 has two independent audio signal generating systems the Analog Generator which provides s
512. z as the Stop value Source 1 Log or Lin Scales If neither the Start nor the Stop value is zero or negative you have the option of calibrating the Source 1 axis with a logarithmic or a linear scale Click on the Log or Lin option buttons to change the scale If either value is zero or negative or if decibel units are chosen these are available for an amplitude source the Log and Lin option buttons will not be available and the scale will be set to linear The choice of scale affects the way that step size is calculated for the sweep and also the distribution of the vertical divisions on the resultant graph Sweep Resolution The range between the Start and Stop values will be stepped through as follows m in equal size increments in Lin scale mode or m in equal percentage increments in Log scale mode The number of steps the size of each step the Log Lin selection and the range between the Start and Stop values are all interrelated Linear Scale Steps When using a linear scale you can set the step size by entering the num ber of steps in the Steps field Only integers between 1 and 65 000 are ac cepted After you have made an entry the value in Stepsize will be ATS 2 User s Manual Data 1 Chapter 15 Sweeps and Sweep Settling recalculated Alternatively you can enter a value in the Stepsize field and ATS will calculate the correct number of steps to produce this step size If the value you enter does not resul
513. zor blade edit that means an angled cut with a computer edit a brief fade up or cross fade is used FFT windowing is similar An amplitude envelope called a window is im posed upon the record data before the FFT processing There are a num ber of different window shapes with different characteristics but they all share this feature they taper at the beginning and end of the record This means that the two ends of the windowed record data match so that there is no discontinuity and the broadband noise is not introduced ATS 2 User s Manual Appendix C FFTs 397 Appendix C FFTs FFT Windowing 1 1 lt j 2 lt 3 3 Figure 293 Application of a Hann window function raised cosine shape to a sinewave viewed in the time domain The windows do modify the acquired signal however which is why there are so many to choose from Windowing spreads the energy in the ac quired signal over several bins and window functions differ in the shape of the resulting spreading The Flat Iop window for example is optimized for flat response at the top of the main lobe but has poorer resolution of closely spaced frequencies than other windows the Hamming window re solves close tones well but has greater main lobe amplitude error and high side lobes 398 ATS 2 User s Manual Synchronous FFTS Appendix C FFTs im Side Lobe Figure 294 Example of a Blackman Harris window function viewed in the frequency domain

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