Home

NTI 010 manual - fra www.interstage.dk

Contents

1. 22 11 45 Valid No Emph JIT 1 1ns Valid No Emph 76 24BF 1 000KHz Error no 20 0 d R H 7 E E i CS EE e 120 dB ao SS ES Fig 25 Digital THD N Sweep of a DAT Recorder at Various Levels NEUTRIK CORTEX INSTRUMENTS 34 49 V5 1 AO10 Digital Extension for A2 User Manual 6 FFT ANALYSIS Basically the digital option AO10 was designed to generate amp analyze digital signals according to the AES 3 and SPDIF standards However due to the computing power of the involved DSP the A2 D can in principal also calculate an FFT Fast Fourier Transformation spektrum analysis on an analog input signal The FFT option article code AO12 adds an 18 bit A D converter module and updates the firmware with the DSP code do to the FFT calculations The modified block diagram of the AO10 with the option AO12 is shown below Central Processing Unit amp Visualisation on large display Logic amp DSP Analyzes amp Generates Generator with DSP Fig 26 Block Diagram FFT Option The A D converter samples the incoming analog signal in the time domain at a sampling rate of 48kHz After each block of 2048 samples the DSP calculates the spectrum from these samples and displays the result in two possible frequency ranges The low frequency range covers 0Hz 5kHz while the high frequency range covers the audio band from OHz 20kHz The calculated FFT spectrum shows the levels of a fixed number of frequencies being distributed ove
2. 40ns Rectifier Peak Bandwidth 700Hz 20kHz Level Measurement Range 120dBF OdBF 0 100 D A Converted Signal Measurements RMS Level THD N RMS calibrated to OdBr with OdBF Sine see analog specifications of A2 Resolution of D A Converter 94dB Mixed Signals Analog generation and digital analysis Digital generation and analog analysis NEUTRIK CORTEX INSTRUMENTS 46 49 V5 1 Outputs User Manual AES EBU at XLR connector channel A on front panel 1104 output impedance IEC958 through RCA and optical TOSLINK connectors at the rear panel with 75Q output impedance X Y Z trigger output through BNC connector at the rear panel Sampling Frequency Accuracy De tuning of fs Carrier Output Level Output Signals Frequency Range Level Range Resolution of Audio Data Dithering Internal Jitter Generator Modulation Signal Output Impedance V 5 1 32kHz 44 1kHz 48kHz or input clock or analyzer clock 10ppm 2ppm on request 1500ppm in steps of 250ppm 100mVpp 5Vpp loaded into 11012 Sine or Sine Dither or Pass or Pass Dither or CRC Test Signal 10HZz to f 2 120dBF 0 dBF 0 100 4 8 12 16 18 20 24bit 1 LSB triangular probability density function 2ns 40ns 84dBUI to 54dBUIl 48kHz Sinusoidal 2 5kHz or White noise with 20Hz 20kHz bandwidth 110Q for AES EBU signals 750 for IEC958 signals NEUTRIK CORTEX INSTRUMENTS 47 49 AO10 Digital Extension for A2 9 IND
3. A typical application of the A D mixed mode is to measure the THD N of an A D converter vs an increasing input level Fig 7 shows such a measurement with and without level limiter The limiter of the A D converter increases the distortion already at a lower input levle but decreases them in absolute terms The other way round Le without the limiter the dynamic range of the A D converter is higher but the distortion increases to a higher end value at full scale THD N Output Analog Input Digital Digital Imp lt 150hm Signallvl1 5 44Vpp PRO 11 01 1996 Sine Fs 48001 35Hz 48 0kHz 21 55 52 74 0dBu 1 000kHz JIT 1 5ns Valid Error no ooa rr e ER E EE ei HT A ET THE KEE A RN IC E LC A LRE EK NS ER ET E E e E E o S E A E O A A PAS E EIERE GE EE TEE RE GER DER O GA ER EEN L e GEET VE O A EN AE LEE O EE eee ere eee eee foc eo gd bali Rd ane Pe te a OES eo ey ae ae ee ee a ee ee PR A A ARMS HECKER ER Pa a ee E EE sh ao O fess oe eee be oe ee Ss Be IH O Ae Sb ee Seo Phe Ske ee GS Ke eB Wmv Sep nea ee oe OS eee TEE Sn Sey WEE A ee ECH Odense eee ER L Bee ON ate o a GE NCR NN BE T CRIN cl SE T Le Lotes 80 0dBu Amptd 5 0dBu DIV 0 00dBu Fig 7 Mixed Signal THD N Response vs Level Switching Back to Digital Analysis To get back to the analog generator mode choose one of the two subsequent possibilities 1 Press the lt GEN SIGNAL gt button to activate the ALT signal 2 Place the cursor to the entry Analog S
4. a value below or above 5kHz Next press the lt STOP VALUE gt button The system will then display the low range if the generator frequency is lt 5kHz or the high range if the generator frequency is gt 5kHz Fig 29 Frequency Band Selection NOTE In the high frequency range OHz 20kHz each screen pixel represents the max level of four neighboured frequencies while in the low range mode OHz 5kHz each screen pixel is identical to one frequency Windowing Functions As required for non periodic signals the FFT transformation of SCOPE the A2 D applies different windowing functions which can be selected through a menu M l l ScopeSetup In the FFT display mode double click to the lt SCOPE gt button Back to TimeDomain to open the ScopeSetup menu Two of the most commonly gt Hannin used windowing functions FlatTop and Hanning are S available The actually selected windowing function is EXIT displayed in inverted letters white on black Change the selection by placing the cursor with the lt SCALE gt wheel and Fig 20 Windowing Functions press the wheel to confirm Zoom Scroll amp Autoscale The FFT display can like the sweep graph be zoomed and scrolled For the operator s convenience the redrawing process of the spectrum is delayed for a few hundred milliseconds in order to allow multiple Zoom and Scroll adjustments Please notice that due to the high refresh rate the lt SCALE g
5. 5 DIGITAL SWEEPS As in the analog mode the A2 D may also perform sweeps on digital signals To do this simply select the digital measurement function in the METER display mode and switch to the GRAPH display mode Enter the setup with start value stop value resolution scaling etc and press the lt DO SWEEP button to let the digital sweep be recorded automatically To store and recall recorded graphs apply the same procedure as for analog sweeps NOTE In opposition to the analog mode the digital measurement function can be changed in the METER display mode only If the AutoDetect mode is active and a digital signal is applied to the AES3 inputs the analog measurement function buttons are inactive If the AutoDetect mode is switched off any press to a measurement function button switches to the corresponding analog analysis mode Following sweep modes are supported in the digital domain e Frequency sweeps from 10Hz to fs 2 with constant level e Tape frequency sweeps from 10Hz to fs 2 with fixed duration per step e Amplitude sweeps from 120dBF to OdBF at a fixed frequency e Time sweeps with a step interval from 3s up to 180hours e Table sweeps with freely definable frequency amplitude pairs Like in the analog mode digital sweeps may be synchronized internally or externally THD N Output Digital Input Digital Digital SignalLv1 5 00Vpp PRO Signallvl 5 44Vpp PRO 11 01 1996 Sine 48 OKHz Fs 48001 35Hz 48 OkKHz
6. 7 are reserved Byte 3 Byte 3 is completely reserved for future application Byte 4 The first two bits define whether the audio signal is a reference signal and of what type while the rest of the bits in that byte are reserved Byte 5 Completely reserved for future applications NEUTRIK CORTEX INSTRUMENTS V5 1 41 49 AO10 Digital Extension for A2 User Manual Byte 6 to9 Theses bytes are interpreted as a set and represent the alphanumeric channel origin data They are normally represented as ASCII characters There exists no restriction what character code is generated by any device Examples may be CD RDAT GEN or A2 Bytes 10 13 Are again ASCII data representing the channel destination data The same restriction as for the channel origin data may be applied Bytes 14 17 Is an ongoing sample counter with 32bits width Even though the counter increases by 48000 units per second the maximum number that can be represented is 2 4 294 967 296 The counter restarts at zero approximately every 25 hours Bytes 18 to 21 The bytes represents in 32bit format the time of day sample address This allows with the knowledge of the sampling address to easily calculate the time difference between any frames Byte 22 This byte carries information about the confidence of the data in the channel status bits The first four bits are again reserved Byte four represents an uncertainties exists in the bytes 0 to 5 while the 1 in b
7. SP DIF are not connected in parallel in order to avoid OPTICAL unwanted interferences between the possibly different input clock signals Therefore it is necessary to select the Sne INPUT OUTPUT active input connector please refer to chapter Input INPUT So Connector p 33 Furthermore it is strongly recommended never to connect a digital signal line to more than one input connector of the A2 D XIVIZ TRIG ER OUTPUT OUTPUT fs Sync Input Fig 3 SP DIF I O Basically there are three different clock rates defined for digital audio signals 32kHz 44 1kHz and 48kHz Additionally the A2 D generator may be synchronized to an external clock with up to 52kHz To do this connect the corresponding clock signal to the fs SYNC INPUT on the rear panel of the unit Please notice that this mode does not allow to de tune the output clock frequency or to create any jitter as described in chapters Fs p 19 and Jitter Amplitude X Y Z Trigger Output Alternatively the A2 D is also able to act as a master by providing different types of output clocks The available clock signals are X Y and Z preamble clock as well as the bit clock for the eye pattern test Monitor Headphone Output Like in the analog mode the headphone output at the rear panel provides the D A converted audio signal of the selected digital input channel In case of the THD N measurement function the reading signal i e the harmonics noise are provided
8. at the headphone jack The headphone output signal is also routed to the internal loudspeaker of the A2 D so that the signal may be monitored without a headphone set as well NEUTRIK CORTEX INSTRUMENTS 8 49 V5 1 AO10 Digital Extension for A2 User Manual How to Use this Manual This User Manual has been designed with you the operator in mind to serve as a complete reference document for using the digital part of the A2 D as a solution to your measurement tasks Familiarize yourself with the A2 D by looking through this manual The best way to feel at ease with the instrument is to sit down with the A2 D in front of you and to start with the next chapter By this way it won t take long to learn to know the instrument and its many features Conventions Following conventions were made in this manual in order to simplify the correlation to the user interface of the A2 D e lt KEYS gt and lt SOFTWHEELS gt are indicated by capital letters between pointed brackets e The Names of settable parameters as well as Menus Menu Entries are in italic e Entry and Result Fields in the digital LC display mode and are written in bold letters NEUTRIK CORTEX INSTRUMENTS V5 1 9 49 AO10 Digital Extension for A2 User Manual 2 OPERATION Activation of the Digital Analyzing Mode Manual Activation If the A2 D operates in the anlog mode it can be switched over to the digital analyzing mode by pressing NOISE CROSSTALK PHASE the lt ADDI
9. gt wheel to open the selection and choose RmsLvl Confirm by pressing the wheel once more Since this is a relative unit measured against a fix reference i e full scale the available units are 1 and d r THD N To activate the THD N measurement function place the cursor to the top left field on the analyzer screen press to the lt SCALE gt wheel to open the selection and choose THD N Confirm by pressing the wheel once more The THD N analysis may be very useful for the analysis of single tone test signals sine It allows quickly to verify the quality of the digital transmission A 16bit audio transmission should achieve a THD N value in the range of 90dB With reduced data width or artificially enlarged word width the THD value will even stay below the theoretical value Also the influence of the jitter to the THD N value is notable when performing analog distortion measurements Monitor Speaker Headphone Output The D A converter always links the incoming audio signal to the analog analyzer Therefore it is possible to listen to the incoming audio signal at any time The signal is fed to the internal loudspeaker to the BNC output of channel A normalized to 1V as well as to the headphone output at the rear panel NEUTRIK CORTEX INSTRUMENTS V5 1 29 49 AO10 Digital Extension for A2 User Manual Analyzer STATus Line Every AES EBU signal incorporates not only the audio data but also some status information a
10. later Since Audio signals are in most applications two channel for stereo reproduction the standards foresee the serial transmission of both channels one after the other completed with additional information Definition The audio data of each channel are packed into 32bit long subframes that start with a 4bit synchronization preamble followed by 4bits auxiliary data and 20 Audio data bits LSB first If less than the max of 24bits 4 auxiliary 20 audio are required the unused bits are set to zero Each subframe is terminated by the Validity flag a User bit the Channel Status and the Parity bit Two subframes one for each channel build together a frame 1 Subframe pets AUX 20BitAudio Dat UEP Dae E A TB _ o EE lt OOCO 6OGAA 27 28 29 30 31 Fig 32 AES 3 Subframe e Please notice that alternatively to the extension of the Audio data to 24bits the auxiliary data can also be used to transmit any other information e The validity flag expresses whether the Audio sample in that word is valid or not e The user bit can be set freely while there exists an AES recommendation AES18 ANSI S4 52 1992 for the format of the user bit 192 frames are always grouped together to a block The meaning of the status bit has to be seen in the larger block contents where these status bits are grouped together to 192 bits whereof some are interpreted as Bytes A detailed explanation follows The parity bit builds a checksum o
11. number 3 Sampling frequency Clock accuracy RESERVED RESERVED Byte 1 The first 3 bits define the category code Depending on the category the interpretation of the next bits in that byte is completely different Byte2 This byte defines in its first four bits the source number with the LSB first The next four bits define the channel number from A to O Fig 36 Consumer Channel Status Byte 3 Decodes the used sample rate in the first four bits Bit 4 and 5 define the accuracy of the clock while bit 6 and 7 are reserved Byte 4 23 The content of these bytes is reserved for future use NEUTRIK CORTEX INSTRUMENTS V5 1 43 49 AO10 Digital Extension for A2 User Manual Signal Transmission Besides the status and audio information there also exist major differences between the physical signal transmission between AES EBU and the IEC958 signal AES defines a balanced transmission while the IEC standard defines an unbalanced electrical or optical link Balanced Transmission The balanced transmission operates with 110Q impedance while the electrical parameters are defined to allow a signal transmission up to a few hundred meters The acceptable carrier level has to be between 0 2Vpp and 5Vpp The lower limit was earlier defined at 2Vpp but has been adjusted to accept also signals coming from an unbalanced transmission without any re amplification x x I I e Line driver y Interconnecting cable Receiver I
12. the eye indicates the level attenuation and degradation while the with of the eye is influenced by the 1 and 0 as well as i Y by jitter The eye height shall be high enough to let the input circuitry PA safely decide between a logical zero E and a logical one Below a certain hysteresis the input device won t be able to make the decision and starts reading errors This is the minimum opening height Fig 39 Construction of Eye Diagram The AES 3 standard specifies the minimum voltage to be Tmin gt bigger than 200mV for at least 50 of the nominal eye TT width gt O Imaged at vertical line Tnom Fig 40 Specs of the Eye Pattern NEUTRIK CORTEX INSTRUMENTS V5 1 45 49 AO10 Digital Extension for A2 User Manual 8 TECHNICAL SPECIFICATIONS Inputs AES EBU through XLR connectors at front panel with 110Q input impedance IEC958 through RCA and optical TOSLINK at rear panel with 75Q input impedance Sample clock through BNC at rear panel Sampling frequency 32kHz 44 1kHz 48kHz or external External clock 25kHz to 52kHz locking range Measurement Functions Digital Measurements Peak Level of Data Carrier 100mVpp 10Vpp Clock Frequency 25kHz 50kHz Frequency Resolution 0 05Hz Frequency Accuracy 2ppm calibrated Bit statistics of complete 32 bit word Status display with decoded information for AES and IEC format Word Clock Jitter Amplitude O
13. the two available units The calculation and relation of these two units is explained in more detail in chapter Units on page 24 Output Signals Sine Digital The digital option offers different selections for the waveforms of the Audio signal output The standard selection is the Sine that corresponds to a digitized sinusoidal waveform with given frequency level amplitude and resolution Pass The second basic audio signal mode is the Pass mode It provides the same Audio signal at the generator output that is actaully present at the analyzer input NEUTRIK CORTEX INSTRUMENTS V5 1 15 49 AO10 Digital Extension for A2 User Manual Nevertheless the level and status of the output signal is created by the A2 D In other terms the digitized audio signal is routed through the unit while its amplitude and status are accessible through the A2 D In this way the operator may change all status information e g resetting the COPY protection bit the signal Format PRO or Consum the Emphasis the word Resolution the audio Output Level the Carrier Level etc according to the demands of the application Additionally the Pass mode allows to use the A2 D as an interface between two digital devices In this case the sampling frequency is automatically locked to the one at the analyzer input indicated by the keyword InpClk on the second line of the LC display Every attempt to change this setting in the Pass mode creates an error messag
14. 0 OAB E a TE EE E a a FA i BIT ND NID BREPAR f Y Wi A Ti PL INN l J ig Wm 4141901 P dc II RAR H iL NI a H F f i R 1 R H IB D A BW ER Fig 31 Printout of FFT Display Leaving the FFT Display Mode There are different possibilities to leave the FFT display mode e Enter the METER or GRAPH display mode by pressing the corresponding key e Open the ScopeSetup menu see Fig 30 and select the Back to TimeDomain entry e Activate a measurement function other than LEVEL or 2 CH NEUTRIK CORTEX INSTRUMENTS 38 49 V5 1 AO10 Digital Extension for A2 User Manual 7 AES EBU DEFINITIONS The demand for digital signal transmission in the professional audio industry forced the AES to release a standard for the standardized transmission of such signals This is the AES 3 or AES EBU standard In parallel the earlier de facto standard introduced from SONY and PHILIPS for Digital Interface SP DIF has also been standardized by IEC958 for unbalanced consumer links The main differences of the physical transmission between the AES EBU and IEC958 standard are level impedance of the cable and the type of connection The transmission standards are beside the mentioned differences more or less identical expect that the AES EBU standard defines only the professional format while the IEC standard covers both the professional and the consumer format The differences between these format will be explained
15. 2 D is capable to measure jitter values from the specified maximum down to values as low as low as 0 5ns Fig 24 Jitter Input Connector The leftmost entry on the second analyzer INPut line allows the operator to select the input connector for the signal to be analyzed To activate the required connector place the cursor with the lt SCALE gt softwheel to this field push it once and select either AES EBU XLR connector CH A on front panel SPDIF RCA connector on rear panel or Optical TOS link on rear panel Validity Bit The Validity information of the input signal is displayed on the bottom line of the screen The keyword Valid indicates that the received audio material is marked as valid while in case of invalid samples the status changes to Invalid Errors The last reading of the bottom line indicates the Errors that occurred during the signal transmission Error State No Noerror has been detected the received digital information is correct Confidence Problems to properly read the incoming signal e g due to high jitter or a too low carrier level The audio information may be faulty Code transmission Nether status nor audio data must be used eee The analyzer is unable to read and interpret the incoming signal as a digital bit stream so that all further digital analysis is useless Table 4 Error States NEUTRIK CORTEX INSTRUMENTS V5 1 33 49 AO10 Digital Extension for A2 User Manual
16. EUTRIK 10 01 1996 10 39 47 Output Digital Input Digital SignalLv1 5 00Vpp PRO BitStatistic Sine 1 On 44 1kHz AUX LSB Audio Data MSBVUCP Valid No Emph 1 O00000XX XXXXXXXX XXXXXXXX OO X X 2 004BF 10 80 Hz l 2 00000000 00000000 00000000 O O X X Fig 19 Printout of Bit Statistic Screen NEUTRIK CORTEX INSTRUMENTS 26 49 V5 1 AO10 Digital Extension for A2 User Manual CRC Test The CRC Test allows to check the transmission reliability of a digital DUT For this purpose the A2 D generates a defined pseudo random noise signal i e a reproducible data sequence which is transmitted through the DUT Next the analyzer calculates a CRC Cyclic Redundance Check Hex word over the received data sequence and displays it to the user Finally the whole test is repeated with the same data sequence in order to compare the results If an identical CRC Hex word results the DUT has transmitted the sequence without any bit losses or changes However in case that the CRC Hex word changes between two or more transmissions the DUT obviously modifies the incoming bit stream in an unpredictable manner NOTE Be aware that any change in gain frequency jitter etc changes the CRC result The CRC test is intended to compare whether digital DUTs are completely identical e g in production To define the CRC test settings proceed as follows by using the lt SCALE gt softwheel Set the generator signal to CRC In the second line enter the d
17. EX A Activation of the Digital Mode 10 AES EBU Deimton ees 39 Analyzer Analog Measurements cooooccocconccccncnnnnnnnos 29 Digital Measurement eee eee eee ee 23 Results Display EE 11 Audio Data E 39 BIT le AIS ua 15 Resolution Indicator sese 30 Signal Frequency eee eee 15 Signal Level 15 Auto Detect Mode 10 A ea Ae Re MENT 37 Auxiliary Data De 39 B Balanced Transmtseon 44 Bi phase Mode sss 40 A ee 26 Block RIZ eT 39 Eeer 7 C Carrier Level Measurement 32 Output Voltage Setting 0000nnnennnn000aaann 19 Category Code 31 Channel Status POSTION hess erect he Ge i 39 40 nie Wei re 30 SOUN EE 18 Clock Out eO 8 COMIC H RT 21 Connectors OVErVieW ee 8 Consumer Format Definition eee 43 Indicator EE 30 THT eech 18 Conventions for the User Manual 9 Copy ds A a 43 Status Indicator EE 31 CRC Generator Mod invicta 17 A E its etal Dard ate hectare less 22 Start Command EG 22 TEST ele 27 D De tuning of Sampling Frequency 19 DIG QUELING EE 19 User Manual Disable Auto Detect Mode 10 Display Cverniew ee ee eee 11 Sene TT 29 RII e Le TT 16 E Emphasis fe ee EE 20 le WE 18 EIERE 33 Eye Pattern Clock Seting EE 21 Output Clock Connechor sese eee e 8 RE 45 F PE KEE E 35 ODS AO EE 36 UO sis eua DE 37 A EE 37 Frequency of Audio Signal sss sese 15 of Digital Input Signal sss sese 30 Resolution of EET 35 E A 8 G Generator ANOD EE 17 CRC Test G
18. I Fig 37 Balanced Connection of AES 3 Signals Please notice that for good and reliable RF shielding both ends of the screen have to be connected in opposition to the practice of analog audio connections where ground loops have to be avoided Unbalanced Transmission The IEC standard recommends an unbalanced or optical link allowing transmission lengths of up to ten meters S I Line driver Interconnecting cable y Receiver____ I Fig 38 IEC958 Unbalanced Connection NEUTRIK CORTEX INSTRUMENTS 44 49 V5 1 AO10 Digital Extension for A2 User Manual Eye Pattern Test The eye pattern test is the only standardized Audio quality test in the AES standard It requires an analog oscilloscope with an external trigger input The interpretation of the results needs some additional knowledge and calculation Every transmission line has a low pass characteristics deforming the shape of an ideal square signal Time instability additionally varies the zero crossing of the signal An ideal square signal is deformed to the lowpass filtered signal Trigger is synchronous to the positive edge of the square signal The trace re starts with the positive slope The scope is then again re triggered with the negative edge of the square signal to draw the trace of the negative shape If the beam density is high enough the screen will show several of the traces forming one e half of the oval eye pattern x The opening of
19. NE l jit Off Sine D1 aUuT Z Fig 13 DigOut Line NOTE All changes in the DigOut line are active only if this menu is open They will be reset to default values as soon as the menu is left This ensures that in normal operation the DUT is fed with a proper signal according to the AES3 standard Carrier Output Voltage The first accessible parameter of the DigOut line shows a number labeled with Vpp It indicates the Carrier Output Voltage that normally equals 5 0Vpp In order to simulate long cables or to test the safety margin of the device under test DUT the A2 D offers the possibility to reduce the Carrier Output Level in 12 steps from 5 0Vpp down to 0 15Vpp for the PROfessional format and from 0 5Vpp down to 0 015Vpp to for the Consumer format NOTE Inthe Consumer mode the Carrier Level value is scaled by factor 10 This means that a reading of 4 0Vpp actually corresponds to an amplitude of 0 4Vpp Fs De tuning In order to test the locking range of a device under test DUT the Sampling Frequency of the generator may be de tuned from the standard values in the range of 1500ppm Keep in mind that this mode is only active if the digital generator is locked to one of the three standardized sampling frequencies 32 0kHz 44 1kHz 48kHz In the Inp Clk and fs Sync mode see STATus Line no frequency de tuning is possible NOTE As long as the Fs De tuning is set to a value 0ppm no Jitter can be add
20. TIONAL gt key which is the second function of BE the lt PHASE gt button Every keypress to this button toggles the analyzer between the analog Phase measurement function and the digital analysis mode To return to the analog mode make sure that no digital signal is present at the XLR input connector and enter Fig 4 Manual Activation of the any of the analog measurement functions by pressing Digital Analyzing Mode the corresponding key The mixed signal analysis is explained in the chapter Mixed Signal Analysis UNCTION Automatic Activation The digital board is equipped with a detection circuitry that recognizes the signal type that is present at the XLR input If a AES EBU signal is detected the digital analysis mode is enabled automatically and remains active as long as the digital signal is present at the XLR input NOTE The automatic signal detector monitors the XLR input connector at the front panel only but not the SP DIF and optical TOS link connectors Disable Automatic Activation SET REF The automatic domain detector can be disabled so that the user a has the full responsibility to set the appropriate analysis mode To disable the auto detect mode double click to the lt SET REF gt key to enter the A2 Setup menu Therein enter the submenu behind gt AutoDetect by using the lt SCALE gt softwheel In the submenu make your choice between ON OFF and confirm by pressing the lt SCALE gt wheel once
21. The output status entry filed is located on the right hand side of the top line in the LC display It allows to define whether the two audio channels that are encoded in an AES 3 signal shall be active or muted The four available states are e On both channels are active e 10n 20n the indicated channel is active only the other one is muted e Mute both channels are muted NOTE Do not mismatch the Output Status with the physical output connectors The AES 3 signal will always be present at output connector OUT A only even when both audio channels are muted NEUTRIK CORTEX INSTRUMENTS V5 1 17 49 AO10 Digital Extension for A2 User Manual STATus Line The STATus line may be displayed by entering the leftmost entry of the second generator line It provides access to the Signal Format the Sampling Frequency the word Resolution the Emphasis and the Channel Status Signal Format The Signal Format is either PROfessional or Consumer see 7 AES EBU Definitions The corresponding status may be monitored best by entering the Status measurement function Sampling Frequency The third field in the STATus mode line allows to set the Sampling Frequency of the generator to one of the following values e 32 0kHz standard AES 3 sampling frequency e 44 1kHz standard AES 3 sampling frequency e 48 0kHz standard AES 3 sampling frequency e Inp Cik the generator synchronizes itself onto the clock of the input signal e fs Sync t
22. Use Manual AO10 Digital Extension for the A2 Audio Test amp Measurement System GEN 1 666kH2 2 68d0BF Sine Walid On Stat PRO 48 kHz SSB it Ho Emph tates CH 1 4 PROFESSIONAL DUD L 0 USE HO EMPHASIS SRC F LOCKED Fs 42 kHz C1 2 CHANHEL Ho USER INFO 2 AUS AUDIO USE 24Bit 3 reserved C4 NO_REF SIGMAL 5 ES 6 3 SC ai Az 16 Dest Cid Smol 64 66 ps D C12 Ver Dn n C22 ALL RELIABLE 23 CRCC CORRECT INP 4 T 1 fen t r2Hz JIT 86 215 n Error no Version 5 1 A2 Firmware V2 46 or higher For all A2 with S No 400 up V5 1 Jan 99 PhS Mbe N A2Proj Options Accessories AO10 Digital u_manual text AO10_51e DOC AO10 Digital Extension for A2 User Manual NEUTRIK CORTEX INSTRUMENTS 2 49 V5 1 AO10 Digital Extension for A2 User Manual INTERNATIONAL WARRANTY Limited Warranty NEUTRIK guarantees the A2 D Audio Test amp Service System and its components against defects in material or workmanship for a period of one year from the date of original pur chase and agrees to repair or to replace any defective unit at no cost for either parts or la bour during this period Restrictions This warranty does not cover damages that have resulted of accidents misuse lack of care the attachment or installation of any components that were not provided with the product loss of parts or connecting the instrument to any other power supply input signal voltage or connector type
23. al format Carrier Level The leftmost reading in the upper analyzer INPut line continuously shows the Carrier Level expressed in Vpp regardless of the selected measurement function It measures the physical peak to peak amplitude of the input signal with a bandwidth limiter applied to filter out possible E transients of the slopes D THH Er Ge The Carrier Level may help to detect level impedance matching and cable loss problems Please notice that the specification for AES EBU signals allows carrier levels in the range of 200mVpp to 5Vpp while the IEC958 format specifies levels in the range of 200mVpp to 500mVpp only Fig 22 Carrier Level with Ringing Sampling Frequency The actaul sampling frequency Fs of the input signal is continuously monitored and displayed in all measurement functions Actually there are two display modes to show the sampling frequency e As absolute value expressed in Hz e g 48000 12Hz 48 Gk Hz Sheen As standard frequency a relative frequency deviation expressed in ppm e g 48 0 kHz 23ppm Fig 23 Relative Sampling Frequency Display To change from the absolute to the relative sampling frequency display place the cursor with the lt SCALE gt wheel to the Hz label behind the sampling frequency Select this item by pressing the wheel once and toggle to ppm Press the lt SCALE gt wheel once more to confirm Jitter The A2 D
24. and seven contain the information about the sampling rate 32kHz 44 1kHz 48kHz and no indication are defined The sampling rates are Alphanumerical channel origin data 0 P C Audio Emphasis Locked Sampl Freq Byte 0 1 Channel mode Use of User bits The first bit designates the format A logical 1 2 Use of AUX bits Length of Audio sample RESERVED 3 4 5 6 7 8 9 Alphanumerical channel destination data not measured but set by the transmitter de 1 Local sample address counter 16 32 bit binary Byte 1 17 The bits 0 to 3 encode the relation of the two channels It ranges from not indicated to two 19 Time of day sample address counter channel single channel and stereophonic All m 32 bit binary further combinations are reserved for future fz applications The second four bits are reserved for the user 22 Reliability flags bits management defining the default mode the Z preamble mode and a user defined 23 Cyclic redundancy check character CRCC application All others are reserved Fig 359 PRO Channel Status Byte 2 Byte 2 defines the use of the auxiliary bits and the length of the Audio data The first three bits code the maximum length of the Audio data to either Not defined 24 bits 20bits or user defined Bits 3 to 5 designate how long the Audio data in the previously defined frame really are Reductions by 0 1 2 3 and 4 bits are defined The bits 6 and
25. block of the transmission contains 192 frames with one Channel 1 subframe and one Channel 2 subframe each Consequently since each subframe contains one channel status bit 192 channel status bits per channel are transmitted with every block Obviously with the start of the next block this status information is repeated In practice the 192 status bits are grouped together into Bytes 8bits to represent ASCII characters The meaning of the bits and bytes in the channel status are different for professional and consumer format Actually only the bit 1and bit 2 of the status are identical to ensure proper decoding of the professional and consumer format NEUTRIK CORTEX INSTRUMENTS 40 49 V5 1 AO10 Digital Extension for A2 User Manual Professional Format The following illustration shows the allocation of the channel status block for professional purposes Byte Bit gt 0 1 2 3 4 5 6 7 RESERVED for description of multichannel recording states the professional format while 0 Audio reference RESERVED represents consumer format Bit 2 indicates whether the transmitted data are audio data RESERVED The three emphasis bits define the type of emphasis used Of the eight possibilities only 4 are used and the others are reserved Bit 5 indicates whether the source sampling frequency has been locked or not If this bit is unlock then the Audio data is not reliable and fo my contain garbage The following bits six
26. by poor I O circuits or clock distribution problems etc All of these problems may cause complex failures ranging from occasionally audible effects to very subtle distortions or even failing systems Fortunately the AO10 extension allows the A2 D Measurement System to operate in the analog digital or even mixed mode The option provides a sophisticated interface to synchronize and handle the AES EBU and IC958 SPDIF formats as well as a versatile digital generator allowing to feed the DUT with all necessary test signal parameters Generator The digital generator supports AES EBU AES 3 and IEC958 signals The provided standard Sampling Frequencies are 32kHz 44 1kHz and 48kHz Additionally the oscillator may also be triggered by the analyzer input or by an external clock The generator supports a Sine signal in the PROfessional or Consumer format with a Resolution from 4bit to 24bits In the Pass mode the analyzer input signal is looped through the unit to the generator output while the status or amplitude of the signal may be modified The built in Jitter feature allows to introduce a defined jitter for acceptance testing Built in sweep capabilities allow e g the quick amp precise qualification of A D and D A converters using the combination of analog generation and digital analysis and vice versa AES EBU signals are brought to from the unit through the XLR connectors at the front panel where the system automatically detects the
27. continuously monitors the peak to peak Word Clock Jitter of the incoming AES 3 signal The measured jitter value is displayed in the field behind the keyword JIT It is expressed in ns 1 nanosecond Joen of a microsecond Alternatively to the absolute ns unit jitter can also be expressed in a relative unit the Unit interval UI Ul expresses the amount of jitter compared to the duration of a frame thus being dependent of the sampling frequency The conversion from the absolute ns to the relative Ul unit and vice versa can be done according to the subsequent formulas dBUI 20 log CETA 0 108 Jitterins 107 LHZD 1 f Equation 1 Conversion from ns to UI NEUTRIK CORTEX INSTRUMENTS 32 49 V5 1 AO10 Digital Extension for A2 User Manual UI 10 UI Jitter s 10 JJI or Jitter ns 10 T Equation 2 Conversion from UI to ns Fig 24 shows how jitter looks like if displayed on an oscilloscope Keep in mind that due to the high speed of the time deviations the bandwidth of such a scope has be very high i e in the range of 200MHz Since the A2 D is an Audio measurement system the bandwidth of the jitter measurement is set from 700Hz to 20kHz to cover the full audio band up to the upper edge The Jitter low frequency limit is set to avoid measurements of the sampling frequency drift and deviation The AES standard specifies that the jitter value must be below 20ns for proper operation The A
28. e Not available in Pass Mode Sine D Pass D Dithering In both the Sine and the Pass mode dithering may be added to the generated signal Dithering is a noise signal with defined statistical characteristics that is added to the LSB of a signal in order to improve the conversion quality of a reduced resolution If for instance a 20bit sine signal with a Probability low level is recorded on a 16bit DAT recorder it will be truncated to the 16bit resolution Unfortunately this process changes the waveform of the original low level sine signal to almost square shape which causes high distortions However by dithering Le adding digital noise to the LSB of the original sine signal the waveform of the truncated signal will remain much closer Fig 11 TPDF Dither to the one of the original signal The price for the thus reduced distortions at low levels is an overall increase of the residual noise floor of about 5dB see Fig 12 4 A Mal ad arde illo dad dl Midd WN HMAT VOIT A et te d e k ee ee l Fig 12 Dithering The implemented dither algorithm of the A2 D is the TPDF dither This is a noise signal with Triangle Probability Density Function It is a white noise signal with a triangular probability distribution and an amplitude of 1 LSB see Fig 11 NEUTRIK CORTEX EE 16 49 V54 AO10 Digital Extension for A2 User Manual CRC Basically the CRC test of the A2 D allows to ch
29. e LCD GEN 1 MB6kHz 6 82dBF Sine Valid On STAT PRO A ons 24Bit No Emphasis Fig 10 Digital Generator Settings The accessible entries of the first line are the output Frequency and Peak Level of the Audio signal the Outout Signal the status of the Validity Bit and the Output Status The second line provides access to further parameters that are used for the signal generation and the status coding Its contents vary in accordance to the mode that may be set through the leftmost entry of the line The following chapters describe in more details the accessible parameters of the generator Frequency The frequency of the digitized audio signal may be set directly through the lt FREQUENCY gt softwheel lt may be set in the range from 10Hz up to half of the sampling frequency which is 24kHz in maximum at the standard clock rate of 48kHz NOTE With the audio signal frequency being set to exactly half the sampling frequency the amplitude of the audio signal is not defined due to the sampling theoreme Peak Level The Peak Level of the digitized audio signal may be varied directly through the lt LEVEL gt softwheel over the entire dynamic range of the selected resolution max 24 bit The output level can be expressed in dBF dB full scale or in percent of full scale To change the unit the analyzer must be set to the measurement function Peak Level wherein every press to the lt UNIT gt button toggles betwen
30. eck whether a purely digital signal transmission provides bit errors or not This is achieved by sending a noise like bit sequence through the signal path and comparing the CRC checksums of the sended and the received sequence against each other If both results are equal no bit errors have occured Normally the CRC test is executed through a single A2 D unit acting both as generator of the CRC test sequence and its analyzer This mode is described in full details in chapter CRC Test However it is also possible to create a CRC test sequence on one unit and analyzing it on another one For this purpose the output signal may be set to CRC without the need to switch the analyzer into the corresponding mode If the CRC selection has been activated the second line of the LC display will automatically show the corresponding entries Please refer to chapter CRC Line for further details Analog Sine The last entry of the output signal selection is labeled with Analog When activating this selection the A2 D switches to analog signal generation while the analyzer remains in the digital mode To switch back to digital signal generation enter the Alt Signal menu behind the lt GEN SIGNAL gt button Validity Bit As it name says the Validity bit indicates whether the audio signal is valid or not see chapter 7 AES EBU Definitions lt can be toggled between Valid and InValid in any digital signal generation mode Output Status
31. ed to the output signal since both features use the same internal circuitry NEUTRIK CORTEX INSTRUMENTS V5 1 19 49 AO10 Digital Extension for A2 User Manual Jitter Amplitude Jitter is defined as the phase i e time variations between the ideal and the actual transients of a digital bit stream In other terms due to poor clock circuitry or die to long cables it may happen that small variations of the ideal sampling instants of an A D converter occur These variations are called Jitter The influence of jitter becomes best noticeable when performing a THD N analysis of the modified signal since jitter creates a non linearity in the transfer curve resulting in increased distortion values The A2 D features a special mode where a user defined Jitter value may be added to the output signal This powerful tool allows to test how sensitive a DUT reacts to a certain amount of jitter The Jitter value itself has to be understood as the total jitter amplitude For instance a value of 20ns means that peak time variations of 10ns from the ideal sampling instants are produced Jitter Modulation Right of the Jitter amplitude the last field in the DigOut line provides access to the Modulation Signal of the jitter To understand the meaning of this signal be aware that the variations explained above don t necessarily alsways have the same amplitude but actually are distributed over the selected range Consequently a modulation si
32. ents results some of them are displayed continuously others to be activated by the user Most of these measurement functions are gained in the digital domain only i e without conversion into the analog domain see next chapter However some of the measurement results are obtained after the D A conversion of the digitized audio data into an analog signal They are explained in chapter Analog Measurement Functions Digital Measurement Functions To select the main measurement function place the cursor to the top left entry of the analyzer display below the horizontal line by turning the lt SCALE gt softwheel Press the wheel once to enter the selection mode indicated by the outlined cursor Each increment of the lt SCALE gt wheel switches to another measurement function In this way choose the required function and press the lt SCALE gt wheel once to confirm and activate the selection Peak Level The Peak Lvi function calculates the TE pAJEF Sines Valid on actaul peak value out of the incoming BE 24Bit Ho Emph digital audio signal ca 1 72 BUdBF 2 BBdBF The result is displayed for both channels simultaneously in numerical letters and in 748 EAEn 1 Ben analog form as a bar graph Please notice that the reading of the bar graph is much STAT Pra 48 BkHz 24Bit No Emph 2 Chni faster than the numerical display thus liMP 4 453Upp Fez 47999 73Hz JIT 8 215 ns allowing to monitor fast trends and RES EU pe Errori
33. esired data sequence duration hours min seconds Set the analyzer mode to CRC Test Enter the desired analyzing duration h m s Start the CRC test through the filed Start in the second generator line GEN 1 000kHz 20 0dBF CRC Valid On CRC Start Oh Om 7s CRCTest Oh Om 10s nt AC62CE AC62CE Restart Armed Armed STAT PRO 48 0kHz 24Bit NoEmph Stereo INP 5 1Vpp Fs 48000 43Hz JIT 0 43ns AES EBU Valid Error no Fig 20 CRC Test Screen e As long as a signal is present at the input the analyzer status right of the Restart field shows Waiting e To start a CRC test at least one second of audio silence zero input must be present During this audio silence on one or both channels the status indicator switches to Audio Silence After one second of audio silence the analyzer shows Armed e As soon as a non zero audio word is received the respective channel switches to Running while the result shows Busy in large characters until the measurement has been finished NEUTRIK CORTEX INSTRUMENTS V5 1 27 49 AO10 Digital Extension for A2 User Manual During the test you can watch the progress on the CRC test progress in form of a countdown for both the generator and analyzer test duration After expiration of the defined analyzing time the 6 digit CRC Hex result is displayed The independently definable generator and analyzer settings allow extended testing possibilities of digital DUTs e For instance the l
34. for each occurrence of the Z preample 9 Channel 1 word start at the beginning of a new block Generates the bit clock of the data stream The bit clock is 64 times the EyePatt j sampling frequency 2 32 bit Table 2 Trigger Output Signals NOTE The trigger output is generated by the analyzer and not by the generator NEUTRIK CORTEX ee V5 1 21 49 AO10 Digital Extension for A2 User Manual CRC Line This line provides access to the output parameter of a CRC test signal i e the length of the sent out sequence and allows the operator to start the transmission To enter the CRC line place the cursor with the lt SCALE gt softwheel to the leftmost field in the second line from the top of the LCD and press the wheel to open the selection Increment the wheel until the setting CRC appears and confirm by pressing the lt SCALE gt wheel once more Fo further details on the CRC test please refer to chapter CRC Test Start By confirming this entry the transmission of the CRC test sequence will be started immediately Please notice that the duration of the sequence has to be set first see below h m s Sequence Duration These three entry fields labeled h m s allow to define the duration of the CRC test sequence in hours minutes and seconds NEUTRIK CORTEX INSTRUMENTS 22 49 V5 1 AO10 Digital Extension for A2 User Manual 4 DIGITAL ANALYZER In the digital mode The A2 D offers a broad variety of measurem
35. gnal must make sure that this distribution follows a certain pattern In the A2 D there are two modulation signals implemented Sine and Noise e In the Sine mode the jitter modulator is a sinusoidal signal with a fixed frequency of 2 5kHz e In the Noise mode the jitter modulator is a white noise source producing an equal distribution of the jitter The bandwidth of the white noise signal is 20Hz to 20kHz NOTE As long as the generator adds Jitter to the output signal the sampling frequency cannot be de tuned since both features use the same internal circuitry NEUTRIK CORTEX INSTRUMENTS 20 49 V5 1 AO10 Digital Extension for A2 User Manual Configuration Line The A2 D provides a BNC trigger output at the rear panel labeled X Y Z TRIG OUTPUT The type of clock that is fed to this connector can be configured in the Configuration line by the user To enter the Configuration line place the cursor with the lt SCALE gt softwheel to the leftmost field in the second line from the top of the LCD and press the wheel to open the selection Increment the wheel until the setting Config appears and confirm by pressing the lt SCALE gt wheel once more Four different clocks are available Name Description Generates a trigger signal for each occurrence of the X preample Channel 1 word start SE a trigger signal for each occurrence of the Y preample Channel 2 word start Triaz Generates a trigger signal
36. he sampling frequency generator is synchronized by the external clock that must be fed to the fs SYNC INPUT on the rear panel Resolution The Word Resolution indicates the number of bits to quantizise the audio signal lt may be set to one of the following values 4Bit 8Bit 10Bit 12Bit 16Bit 18Bit 20Bit 22Bit 24Bit Emphasis This field allows to activate a frequency response correction in order to improve the dynamic range of older digital recordings Following selections are available Emphasis Filter Type PROfessional Mode Consumer Mode NoEmphasis 50 15us CCITT Table 1 Emphasis Filter Availability Channel Status The last entry of the STATus mode line refers to the Channel Status of the audio signal e Stereo indicates that the digitized audio signal is a true stereo signal e 2 Chn indicates that the two channels of the digitized audio signal are completely independent e not a stereo signal e 1 Chn indicates that both audio signal channels transmit the identical 1 channel signal NEUTRIK CORTEX INSTRUMENTS 18 49 V5 1 AO10 Digital Extension for A2 User Manual DigOut Line The DigOut line can be activated by placing the cursor with the lt SCALE gt softwheel to the leftmost field in the second line from top of the LCD and pressing the wheel to enter the selection Increment the wheel until the setting DigOut appears and confirm by pressing the lt SCALE gt wheel once more Walid Cir GE
37. ier Level Frequency Deviation Jitter active Input Connector as well as the Validity and Error status Please refer to 7 AES EBU Definitions for the specifications of AES EBU signals More detailed explanations about these settings are filed in the chapter Digital Analyzer NEUTRIK CORTEX INSTRUMENTS V5 1 11 49 AO10 Digital Extension for A2 User Manual Printouts By pressing the lt PRINT gt button the information of the actual display will be printed out to a connected printer 10 01 1996 10 33 18 Output Digital Input Digital Signallv1l 5 00Vpp PRO Signallvl1 4 98Vpp PRO PeakLvl Digital Sine 48 OKHZ Fs 48000 24Hz 48 OKHZ Valid No Emph JIT 0 7ns Valid No Emph 1 2 OOABF 2 00dBF 275 8 Hz Error no 2 12 OOABF mem eae ee ee n A ee ee ee ee ee e EE EE ees ees wc ee oe r been a ee ee ee a SS SS SS SS SS SS SS G e ee Fig 6 Printout of Digital METER Display Mixed Signal Analysis Apart from the purely analog or digital mode the A2 D may be operated in the mixed signal mode as well This means analog signal generation with digital analysis or digital signal generation with analog analysis The normal way to set up the instrument in any of the available modes is to set first the analyzer and then if necessary to modify the generator mode This procedure is explained below Digital Analysis Analog Generation Activate the digital analyzer as described in chapter Activation of the Digita
38. ine in the generator status line and toggle to Digital Sine by using the lt SCALE gt softwheel GEN Z LS SG HZ Y dBY Jut 6200 Sp B 5 8624 Fig 8 Generator Status Line in Analog Mode NEUTRIK CORTEX ee V5 1 13 49 AO10 Digital Extension for A2 User Manual Analog Analysis Digital Generation In order to switch the analyzer of the A2 D to the analog mode while operating the generator in the digital mode proceed as described in chapter Leaving the Digital Analysis Mode p 10 As soon as the analog analysis mode is active the digital a output signal may be activated like any other alternate signal C Simply double click to the lt GEN SIGNAL gt button to open the Fei Alt Signal menu Therein either choose the DigSine or DigSineDith entry by using the lt SCALE gt wheel Consequently Alt Signal the generator will change into the digital mode while the Square Sym analyzer remains in the analog analysis mode Square Asym riangle In this mode the digital generator is controlled through the IMD TestSig three softwheels as explained in chapter 3 Digital Generator White Noise Pink Noise while the analog analyzer may be operated through the keys on the A2 D front panel Narble DigSineDith EXIT Operation Philosophy Selections and Changes In order to keep the user interface for the digital features as simple S Ser as possible but without overloading the keyboard by triple function
39. input connector automatically detects the signal type and activates the corresponding mode Digital analysis is performed in the DSP itself The signal is parallel applied to the D A converter for acoustical monitoring Generation of AES EBU signals is also performed by the DSP For jitter generation the analog generator is used as the jitter source providing different waveforms frequency and amplitude NEUTRIK CORTEX INSTRUMENTS V5 1 7 49 AO10 Digital Extension for A2 User Manual Connectors Overview AES EBU signals are normally connected through XLR connectors that are terminated with 110Q while the IEC958 signals SP DIF are connected through RCA or optical TOSLINK connectors with 750 termination AES EBU in amp outputs are available at the front panel of the A2 D The XLR connectors of CH A and only CH A are prepared to handle both digital and analog signals Due to the fact that a 2 channel digital audio signal is encoded in a serial bit stream it is transmitted through one cable thus requiring only one I O connector each Please refer also to chapter 7 AES EBU Definitions The RCA and optical TOS link connections are provided at the rear panel of the A2 D They are marked with INPUT and OUTPUT The digital output signal is always available simultaneously at all three output connectors Fig 3 AES 3 I O On the other hand the three input connectors XLR RCA DIGITAL OPTION P and
40. it five indicates a possible error in the bytes 6 to 13 Bit six states an unreliability in the bytes 14 to 17 A problem in the bits 18 to 21 is then signalized in bit 7 Byte 23 Contains a 32 bit checksum CRC over all channel status information to indicate possible bit changes during transmission The polynomial is G x X X X 4 X x 1 NEUTRIK CORTEX INSTRUMENTS 42 49 V5 1 AO10 Digital Extension for A2 User Manual Consumer Format The consumer was formed out of the earlier SONY and PHILIPS standard These companies worried most about the copy protection while the discussion is still not finished how the copy flag shall behave after the first or second copy through the digital output The consumer status block defines much less information than the professional format Only the first four bytes are defined the rest is unused Byte 0 Byte Bit gt 0 1 2 3 4 5 6 7 0 P C Audio Copy Emphasis The use of the first bit is identical with the professional format to ensure homogeneous interpretation of the formats Bit one defines Audio or non audio use Bit 2 is already different from the professional format the copy protection bit With this bit being zero no copy of the audio material is allowed Bits 3 to 5 define the type of Audio data while bit 6 and 7 always are set to zero The scheme for the copy protection is not yet fixed but still under development Category code 1 2 Source number Channel
41. ital Extension for A2 User Manual Bit Statistics Another measurement function of big help for the test and diagnosis of a system is the BitStatistics function It visualizes the state of all bits in the digital audio signal covering the AUX bits the audio data as well as the User Validity Status amp Parity bits The Bi reen allow ickl GEM 1 G66kHz 2 86dBF Sine Walid On 4 Stat screen allows to see quickly Stat PRO 48 kHz 24Bit Ho Enmph which bits of the audio data are permanently low 0 high 1 or changing 1 BitStat AUX LSB Audio Data HSR U U C p In this way e g the resolution of the encoded E audio word can be verified immediately Just IIIZ IILI ILIZ D D check how many of the 24 bits below the AUX and MSB labels are actually changing STAT Fro 9 46 8kH2 4Bit Mo Emph 2 Chn indi i INF 4 453Upbp Fs 47999 75H2 JIT 0 215 ns indicated by the SRN AES EBU Walid Error no If some of the bits are constantly 0 the resolution of the audio signal is obviously less Fig 18 Bit Statistic Screen than the maximum of 24bits If the Validity bit is permanently O the incoming data are valid The User bit is not used i e constantly 0 The Status and the Parity bit are both normally changing Printout To print out the contents of the Status screen connect a printer to the Centronics connector on the rear panel of the unit and press the lt PRINT gt button Fig 16 shows an example of such a printout N
42. l Analyzing Mode on page 10 of this manual Consequently both the analyzer and the generator are set to the digital mode Now there are two possibilities to set the generator to the analog mode e Place the cursor with the lt SCALE gt wheel to the Output Signal field in the top line of the LC display Press the lt SCALE gt wheel and turn it until the keyword Analog appears Confirm the selection by pressing the SCALE wheel The generator status line changes then immediately to the known analog generation status information GEN 1 BBBkHz 6 2dBF Analo Valid Ur STAT PRO 45 kHz 24b1T Ho Enmnphaz1 Z As long as the generator is in the digital analysis mode the LED below the censicnal lt GEN SIGNAL gt button lights the ALT label By pressing the lt GEN SIGNAL gt key once the output signal toggles from ALT digital output to analog sine Cy Le the analog generator will be activated In this mode the generator can be operated exactly the same way as in the analog only mode except the following restrictions 1 Only the sinusoidal output waveform may be generated 2 When pressing the lt IMPEDANCE gt button only the output impedance will change but not the input impedance 3 The level unit of the analog generator can be altered only if the digital analyzer is set to the PeakLvl measurement function NEUTRIK CORTEX INSTRUMENTS 12 49 V5 1 AO10 Digital Extension for A2 User Manual Application Example
43. lt Ho Ech field of the analyzer screen Press the lt SCALE gt wheel once and turn it until Status appears Press the lt SCALE gt wheel once more to confirm HO EMPHASIS E reserved GE The A2 D directly translates the contents CROC CORRECT of the status bits and displays the result on rnp a 4 453Upp F Fez 47999 3H2 IT 0 215 n the Status screen thus enabling the user HEEB Errors no to directly read the Meanings Fig 16 Status Screen Professional Format The proper interpretation of the status bits for both the Professional and the Consumer format is done automatically by the A2 D Therefore there are two different layouts of the Status screen L L L L L L L Printout To print out the contents of the Status screen connect a printer to the Centronics connector on the rear panel of the unit and press the lt PRINT gt button Fig 16 shows an example of such a printout NEUTRIK 10 01 1996 10 38 42 Output Digital Input Digital SignalLv1 5 00Vpp PRO Status CH 1 Sine 48 OKHz O PROFESSIONAL AUDIO USE NO EMPHASIS Valid No Emph SRC F LOCKED Fs 48 kHz 2 00dBF 10 80 Hz 1 STEREO MOD NO USER INFO 2 AUX AUDIO USE 24Bit 3 reserved 4 NO REF SIGNAL 5 reserved 6 9 Origin A2 10 Destin 14 Smp1 00 00 00 00 18 T 00h00m00s00 22 Byte ALL RELIABLE 23 CRCC CORRECT Fig 17 Printout of Status Screen Professional Format NEUTRIK CORTEX INSTRUMENTS V5 1 25 49 AO10 Dig
44. more A2 Setup Store Setup Recall Setup Recall Default gt Interface Calibrate A2 gt Set Clock gt AutoDetect EXIT Leaving the Digital Analysis Mode If the automatic signal detector is disabled the digital analysis mode can be left at any time by selecting an analog measurement function such as Level THD N Noise etc Alternatively i e as long as the auto detector is active the operator has to make sure that no digital signal is present at the XLR input connector The SPDIF and optical inputs do not feature an auto signal detector their connection is not of importance NOTE With the Auto detector being active and a digital input signal being present at the XLR input there is no way to leave the digital analysis mode NEUTRIK CORTEX INSTRUMENTS 10 49 V5 1 AO10 Digital Extension for A2 User Manual Display Overview In the digital mode the LC display will look similar to the one of Fig 5 Please notice that the the layout of the screen may vary according to the actuial status of the unit However these variations have no influence on the following explanations 1 B kHz 6 02dBF Sine Valid On geht 1 SE 48 6kHz 24Bit No Emphasis PeakLw l 1 6 2dBF2 6 02dBF D 000 dEr STAT PRO 48 BkHz 24Bit No Emeh 2 Chri INP 5 290UPP d gk HZ ati JIT 6 00 ns DEG EDU Valid rror no Fig 5 Example of the Digital Display Generator Settings The top area of the screen is always reser
45. nd codes that indictae the validity of the sample The STATus line of the analyzer display shows some status parameters of the input signal SE Hz 2 HOPE Sine Walid ed is SC Hz dB it H Bitst at Ha LSE Audio Data HSE UW U C P TEE ek LEELA G G F FEEEFEEE FEEFEEFE FEEFEE G G Z STAT Pro 45 BkHz 24Bit Ho Enmph 2 Chn IMP 4 aa Fs247999 r3H2 JIT 8 215 ns Walid Error no HES EB Fig 21 Digital Display with Analyzer Status Line Although this information does not fully describe the signal status it reflects at least the most important values PROfessional or Consumer indicates whether the received signal has professional or consumer format Depending on this format the remaining states differ from each other see also chapter 7 AES EBU Definitions Regardless of the signal format the next entry of the analyzer STATus line refelcts the clock of the input signal It shows the sampling rate with which the audio data have been digitized Standard values are 32 0kHz 44 1kHz and 48 0kHz However in the InpClk mode the numerical result disappears so that the input clock can be obtained via the Fs field only see below STATus Line in PROfessional Format The leftmost entry of the line indicates the signal format PROfessional followed by the Input Clock Please notice that the displayed value always equals one of the 3 standard sampling rates 32 0kHz 44 1kHz or 48 0kHz Next the Resolution indicates
46. ng tendencies Fig 14 Peak Level Screen Printout To print out the contents of the Peak Lvl screen connect a printer to the Centronics connector on the rear panel of the unit and press the lt PRINT gt button Fig 15 shows an example of such a printout 10 01 1996 10 33 18 Output Digital Input Digital SignalLvl 5 00Vpp PRO SignalLvl 4 98Vpp PRO PeakLvl Digital Sine 48 0KHz Fs 48000 24Hz 48 OKHZ Valid No Emph JIT 0 7ns Valid No Emph 1 2 O000QBF 2 00dBF 275 8 Hz Error no 2 2 OOABF Fig 15 Printout of Peak Level Measurement NEUTRIK CORTEX STEMMEN V5 1 23 49 AO10 Digital Extension for A2 User Manual Units The peak level can be displayed in two different units dBF decibel full scale and percent of full scale Obviously the peak level units refer to the maximum possible level of the digital signal 100 or 0 dBF Calculation Linear Full scale EE 100 Max_ Value Full scale Actual_ Value 20 lo OdBF Bul Max Value Table 3 Digital Peak Level Units Logarithmic NEUTRIK CORTEX INSTRUMENTS 24 49 V5 1 AO10 Digital Extension for A2 User Manual Status Display The Status of the digital audio signal is encoded in the subframes of the AES 3 bit stream Every 192 frames the status is repeated see chapter 7 AES EBU Definitions To activate the Status measurement Lee 1 060kH2 2 00d8F Sine Valid oe function place the cursor to the top left te PRO 45 8kH2 24E
47. oconcncncoconcncnnoncnnnnncnncnnncnnnncnno 39 Dweenpne 34 T Technical Specifications 46 Termination of CGopnnechors e e e 8 THD N ee 29 U Unbalanced Transmission o 44 User Bit Detmiton eee 39 V Validity Bit SEWING EEN 17 Dei id 39 Indicator EE 33 W Warranty coooccccooccccnnnccnonncoconncononnccncnnnenonnnos 3 VC lte e E 37 X XIYIZ Trig QUID EE 8 Z A a a a 37 interstage Phistersvej 31 2900 Hellerup Danmark Telefon 3946 0000 fax 3946 0040 www interstage dk pro audio with a smile NEUTRIK CORTEX INSTRUMENTS V 5 1 AUDIO ANALYZERS PSYCHOACOUSTICS 49 49
48. onal seene 17 A e aE 16 A 15 GMC O E E S 15 Output el EE 15 Pass MOE rere ne 15 Status RT e 11 H Headphone Output 8 29 How to Use this Manual see eee 9 I SE 39 aje Bn EE ER Input Clock Measurement eee eee ee 30 Connect eegend 33 J Jitter GENET eT 20 Measurement da 32 le el LEE 20 le E ER NEUTRIK CORTEX INSTRUMENTS 48 49 V5 1 AO10 Digital Extension for A2 L Level OF Audio SIONA EE 15 OF Cater DUT ices aana zra az a 45 else 32 of Carrier Output asses sees eee eee 19 M Manual Activation of the Digital Mode 10 Mixed Mode A D oeie 12 DSA TE 14 Mode Switching Rules 14 Monitor Goezaker see eee 8 29 O Operation Phulosopbw ee eee ee 14 Output Clock Signals Setting eee 21 Status Setting AA 17 X YIZ de e E 8 A ee EE 6 P Parity Bit Deimmton eens 39 Pass Mode sees 15 Peak LV sango nayan gha yei ana gaar roan 23 IN ul e 39 CHOCK COUT e EE 8 RS Ny a Po e 39 Professional Format Definition ss eee eee eee etea 41 ale e e TEE 30 esn l i POP o 18 R Resolution of Audio Data Setting sss sese eee eee 18 OPA eee te ne eee ee 38 RMS e 29 S Sampling Frequency Kin gro Pre P P t renn ennneee nnen 19 User Manual Measurement eee 30 32 Elle WEE 18 o E TE E AE E 37 Signal FOrMat isaac ena 18 Transmission e e e e e e 44 Sine Output Gigonal sss eee 15 Specifications eee e e e 46 Spectrum Analysis eee e 35 STAT TEE 30 Status leese 25 LING ee Ee 18 Gubtrame doc
49. onger the generator and analyzing duration are the larger becomes the variety of transmitted words within the data sequence i e the tougher becomes the test e A generator duration far longer than the analyzing one allows to measure other audio data after completed CRC test e Changes of other setup settings such as frequency level word length etc allow to test digital DUTs under a wide range of conditions NOTE Please notice that for direct comparison between two or more measurement results no changes of the generator and analyzer settings are allowed NEUTRIK CORTEX INSTRUMENTS 28 49 V5 1 AO10 Digital Extension for A2 User Manual Analog Measurement Functions The digital interface board AO10 is equipped with a high performance D A converter that allows to link the received digital signal to the analog analyzer of the A2 In this way analog measurements of the incoming AES EBU signal may be performed as well RMS Level The digital Peak Level measurement described previously provides information about the peak to peak signal level compared to the full scale of the converter On the other hand with the analog RmsLvl measurement function it is also possible to measure the RMS level of the digital input signal As reference level a sine signal with OdBF peak to peak level is assumed To activate the RMS Level measurement function place the cursor to the top left field on the analyzer screen press to the lt SCALE
50. press the lt SCOPE gt button Depending on the actual setup of the A2 D the input signal will M be displayed either the in the time or the frequency domain ScopeSetup atime Domain Freq Domain EXIT To toggle between these two modes open the ScopeSetup menu by double clicking to the lt SCOPE gt button Therein either choose Time Domain scope display mode or Freq Domain FFT display mode by using the lt SCOPE gt softwheel Press the wheel once to confirm Fig 27 Scope Setup Menu In the FFT display mode any change of the measurement function to another one than 2 CH or LEVEL switches the display back to the SCOPE mode A er E Cum Q DA N fy a iy L u du D Hd Hz 16591 155 Fig 28 FFT Display of a Sine Signal Fig 28 shows a FFT spectrum in the low frequency band from OHz to 5kHz The X axis represents the frequency with each pixel step corresponding to 23 4Hz The level of the peak signal at 1kHz is 80dBu representing the RMS value of that single frequency Please notice that the measurement accuracy of the FFT is limited to lt 2dB due to the so called picked fence effect NEUTRIK CORTEX ee 36 49 V5 1 AO10 Digital Extension for A2 User Manual Frequency Range The FFT display has two possible frequency ranges SWEEP n one from OHz 5kHz and the other from OHz 20kHz START STOP SWEEP MODE LA To select either range set the generator frequency to
51. r the X axis The scheme in which these frequencies are arranged indicates the Frequency Resolution of the spectrum i e the frequency spacing Af f _ 48000Hz RS 23 4 Hz NoOfSamples 2048 Af Equation 3 Frequency Resolution of FFT Therefore the FFT spectrum theoretically displays every 23 4Hz a frequency i e all together a set of 1024 frequency samples up to the Nyquist frequency of f 2 Consequently in the high frequency range OHz 20kHz 856 frequencies should be displayed However since the LC display has 214 lines in the graphical area available only every displayed level actaully represents the maximum value of four neighboured frequencies while in the low frequency range OHz 5kHz the display resolution is big enough to represent every frequency by an own line NEUTRIK CORTEX INSTRUMENTS V5 1 35 49 AO10 Digital Extension for A2 User Manual If a FFT spectrum is printed out all calculated frequencies are printed regardless of the selected frequency range due to the sufficiently high resolution of the printer Operation The FFT display mode is an alternate mode of the SCOPE display and can be opened in the analog mode only NOTE The FFT analysis is available in the analog mode only for measurement functions LEVEL or 2 CH Digital signals cannot be generated as long as the FFT display mode is active To enter the FFT mode first set the measurement function to SCOPE either LEVEL or 2 CH and then
52. s SCROLL or complex menus all selections in the digital mode are performed PUSH through the lt SCALE gt softwheel only AUTO Each increment of the lt SCALE gt wheel moves the cursor white on ea black to the next editable entry If one wants to alter the entry simple press the wheel once thus reverting the cursor to outline lt 1 lt i i_ This indicates that the respective parameter may be changed In this mode an increment of the lt SCALE gt wheel alters the displayed rre 9 lt SCALE gt Wheel entry to the next available one in the list To confirm a selection press the lt SCALE gt wheel once so that the cursor reverts back to inverse while the selected entry becomes active Mode Switching When switching between the modes of the A2 D analog digital there are two rules to be considered 1 Always change the mode of the analyzer first and then if required the one of the generator 2 When the analyzer mode is changed the generator will always assume that status it had when the analyzer was in the respective mode the last time NEUTRIK CORTEX INSTRUMENTS 14 49 V5 1 AO10 Digital Extension for A2 User Manual 3 DIGITAL GENERATOR The A2 D incorporates a fully digital generator that allows to feed devices under test DUTs with all kinds of digital test signals The information about the actaul settings of the generator are indicated like in the analog mode on the top two lines of th
53. signal type analog or digital and enables the corresponding analysis mode RCA and optical TOSLINK connectors are provided at the rear panel together with the input clock and the trigger output BNC connectors Analyzer The analyzer continuously measures the Sampling Frequency as well as the Carrier peak amplitude thus indicating cable loss and impedance mismatching problems The clock for the D A or A D conversion is normally derived from the input signal itself Since word clock jitter is responsible for poor audio data the AO10 continuously measures this type of Jitter in two ranges a wider range for the less accurately specified consumer products and a very precise range with a resolution of less than ins for professional equipment An on line Status Bit analysis covers the contents of the status and the auxiliary bits which are displayed in binary and also as decoded information Transmission problems like parity errors lacking confidence validity and lock mode errors are recognized and displayed The Bit Statistics easily detects hanging bits in any position of the word including the audio data and AUX bits to quickly find failing bits A high performance D A converter enables the user to monitor the coded audio signal to identify lines and channels An internal link from the converted signal to the analyzer of the NEUTRIK CORTEX INSTRUMENTS 6 49 V5 1 AO10 Digital Extension for A2 User Manual A2 D allows to do all the conven
54. ssional FO Mali ee ee As 30 STATUS Line mM Consumer Format see ea a a a aa a a a 30 A aly el En ar bd 32 Carrier EVE EEN 32 Samplna FREQUENCY TTT 32 n EE 32 PUL COMMECION TT 33 A EES E E E 33 TGT O 33 DIGITAL SWEEP sitial loas 34 Ki BREET 35 e aae eA E E EE T A T 36 PFOGUCIICY ae LT 37 WV IIOO WAC UNIC lo 37 eelerer Ree 37 PRIOR ari 38 Leaving the FFT Display MOQ osorno iaa 38 AES EBU DEFINITIONS ee See ae 39 Bt de EE EE 39 ele Reen Ee HT 40 Channel Staue INfORMAUOM T 40 Frotessional FORMA EE 41 CONSUME e EE 43 Signal ansia a aci n 44 Balanced Trans MISSION ia 44 Unbalanced eT NIE Le BEE 44 S ng EE 45 TECHNICAL SPECIFICATIONS cid 46 last 46 Measurement FUNCTIONS at A A 46 leie CNIS o 46 D A Converted Signal Measurements eee e eee eee 46 Mied SIGN AIS EE 46 OUMU eee nr oi oie coc 47 WEE geed 48 NEUTRIK CORTEX INSTRUMENTS V5 1 5 49 AO10 Digital Extension for A2 User Manual 1 INTRODUCTION The AO10 digital option is an extremely useful and versatile extension for the A2 Audio Measurement System It offers all necessary functions to reliably test AES EBU signals connections or functions analyzed through balanced unbalanced or optical links Nevertheless the operation of all these measurements is as simple of the analog part In paractice when working in a mixed signal environment manifold problems may arise non matching sampling rates format incompatibilities impedance mismatches jitter being introduced
55. t wheel is less frequently checked with a stable display than in the redraw mode An important difference to the normal graph operation concerns the auto scaling since the autoranging circuitry uses the RMS level to define the optimum display scale With signals showing a high crest factor peak to RMS level ratio such as noise signals the auto ranging may fail so that the scale may not optimized or the signal may exceed the display Re adjust the scaling in this case by Zooming and Scrolling accordingly The FFT display can be frozen at any time by pressing the lt SCOPE gt wheel once The next press to the lt SCOPE gt or any other measurement function or lt UNIT gt button releases the freeze mode i e the display will be refreshed continuously If the instrument is re ranging its input amplifiers the message Ranging will be displayed in the top right corner of the display During that period the system is not able to display any spectrum NEUTRIK CORTEX INSTRUMENTS V5 1 37 49 AO10 Digital Extension for A2 User Manual Printouts Every FFT spectrum can be printed out by pressing the lt PRINT gt button The printout is handled in parallel to the FFT calculation so that the display will be refreshed continuosly even during the printout process LEVEL Output Analog Input Analog 11 01 1996 Imp lt 150hm Imp 100kOhm Filter 22 50 57 Sine Off 11 8dBu 1 781kHz A 20 2dBu 1 781kHz o EE a a a a Ee DE a do E ER 4
56. tal Analyzing Mode cccccoonccncccnoconnccnonccncnonannnnnononcnnnnnnnrennnonnrennnnnns 10 Manal ACUY AOI A Ed 10 PLUTO MATIC SACU ANON cta ro 10 Leaving the Digital Analysis Mode 10 BIS Ke TT 11 Generator Send EE 11 Analyzer E UE 11 PIO TT 12 Mied SIGN al E 12 Digital Analysis Analog Generation 12 Switching Back to Digital Analysis nnn0a0annnnnoennnnneenernnenernsrennrrressrrrrrrerssrrrrreennenne 13 Analog Analysis Digital Generation 14 Operatorni PNOSODAY arica it lila 14 Selections and Chal Susana oca 14 Mode te e EE 14 Klee 15 Sre LL eT 15 GENEE 15 KEE 15 SIMS DIM ANN EE 15 EE 15 Sine D Pass D ER E ee EE 16 E LEE 17 Ale ere NG NEE 17 II e T E o dd Ws EE 17 STATUS LING EH 18 Signal FOMA ai decana 18 Sampling Pre quenty necio 18 Sie lE a ala en oree 18 EMP EE 18 ONIS einen 18 DOU IE oh aan il 19 Carrier Output VONAG EE 19 A TTT 19 A Ee 20 Insig eae geen 20 NEUTRIK CORTEX INSTRUMENTS 4 49 V5 1 5 6 7 9 AO10 Digital Extension for A2 User Manual Configuration LIne ct ats a ales al ad oe teed een acter tel ance anes aces vende eect 21 ORO EE 22 EE AAA A A EAE AAA AE E A A AST E EF 22 mie Ree Tle RL e E 22 IG TEAL ANAL ZER EE 23 Digital Measurement Elene 23 EE 23 Status DIS a T A E Aaa A AE 25 a A sa EE 26 CT EE 27 Analog Measurement FUNCTIONS AEN 29 AMS GT 29 db ol EC 29 Monitor Speaker Headphone Output 29 Analyzer STATUS LING Arona 30 STATUS Line in PROfe
57. than specified In particular no responsibility is granted for special incidental or consequential damages This warranty becomes void if servicing or repairs of the product are performed by any other party than an authorized service center No other warranty written or oral is authorized by NEUTRIK Except as otherwise stated in this warranty NEUTRIK makes no representation or warranty of any kind expressed or im plied in law or in fact including without limitation merchasing or fitting for any particular pur pose and assumes no liability either in tort strict liability contract or warranty for products NOTE In case of malfunction take or ship prepaid your NEUTRIK A2 D Audio Test amp Service System packed in the original packing to your nearest authorized service center Be sure to include a copy of your sales invoice as proof of purchase date Transit damages are not cov ered by this warranty NEUTRIK CORTEX INSTRUEMNTS Division of NEUTRIK AG Im Alten Riet 34 FL 9494 SCHAAN Principality of Liechtenstein Tel 41 75 237 2424 Fax 41 75 232 5393 E mail techsupportOneutrik lol i NEUTRIK CORTEX INSTRUMENTS V5 1 3 49 AO10 Digital Extension for A2 User Manual TABLE OF CONTENTS INTRODUCTION EE 6 Generali ata ia 6 ai WEE D PROTO Block DAOA WEE 7 Connector EE ad 8 SOY AS MPU eer E E ico 8 ANIZ iets L EU 8 Monitor Eeler EEN 8 Howto EIER En EE 9 GOW e EE 9 OPERATION EE 10 Activation of the Digi
58. tional analog audio analysis with the digital signals e g measurements of the RMS Level or the THD N distortion of the signals Peak Levels can be measured digitally and are expressed either in dBF dB Full scale or percentage A dual channel analog bargraph complements the result presentation in real time The SYNC output provides selectable trigger signals of either the X Y or Z preamble The FFT option AO12 further enhances the analyzing abilities of the system by introducing a new display mode for the analysis of analog input signals in the frequency domain Actually the FFT feature provides a real time spectral analysis with a high dynamic range from OHz 5kHz or OHz 20kHz thus adding a real time spectrum analyzer RTA to the system AO10 Block Diagram The AO10 digital option can be regarded as an independent analyzer generator board with switchable in amp outputs An internal link to the analog analyzer of the A2 through the D A converter allows to make the digital input signal audible and to analyze it with the standard analog measurement functions Ee r G Central Processing I I E Analog Unit amp Visualisation Filters Meter l on large display Lg D A E S H Speaker amp Converter O Monitor Outputs A Sam Inputs Analyzes 8 me H Generates Analog Generator i Logic amp DSP Jitter Modulation with DSP Outputs Fig 1 Block Diagram The detector behind the XLR
59. ved for the generator settings regardless of the selected measurement function From left to right the first line starts with the output frequency amp level followed by the output signal the Validity status and the Channel status The layout of the second line changes according to the selection of its leftmost entry e In the STATus mode the signal format PROfessional or Consumer the sampling frequency the resolution and the Emphasis status are accessible e Inthe DigOut mode the carrier level frequency deviation as well as the jitter amplitude and modulation signal may be adjusted e Inthe Configuration mode the output clock signal may be e Inthe CRC mode the test sequence may be controlled in terms of its duration hrs min sec and transmission start command More detailed explanations about these settings are filed in the chapter 3 Digital Generator Analyzer Results The analyzer part takes all the space below the vertical line It shows in its top left corner the name of the current measurement function followed by the corresponding results displayed in numerical figures and depending on the measurement also in form of an analog bar graph The lower part of the display is reserved for the input signal status and parameters Except of the STATus measurement mode this part shows from left to right and top to bottom the acquired signal Format Sampling Frequency Resolution Emphasis and Channel Status Carr
60. ver the subframes to find single bit errors Subframe 1 Subframe 2 Frame 191 li Frame 0 d Start of Block Fig 33 Start of Block with Preamble One block of consists of 192 frames as illustrated above Therein each subframe is headed by an individual preamble whereof the X preamble marks the A channel and the Y preamble the B channel A special preamble the Z preamble replaces at each beginning of a block NEUTRIK CORTEX INSTRUMENTS V5 1 39 49 AO10 Digital Extension for A2 User Manual the X preamble once to indicate the start of a new block This allows the receiving devices to trigger to the data stream and to find the beginning of a block which is evident for the proper interpretation of the signal Signal Transmission The signal transmission is performed in the so called bi phase mark mode This mode has been chosen to minimize the DC component in the physically transmitted signal The illustration below shows that a logical 1 is represented by a polarity change in the middle of the source signal while a logical 0 does not show this transition Please notice that the clock of the digital bitstream therefore has to be twice the sampling rate times 64 2 channels with 32 bits which results in a clock of 6MHz at a given sampling rate of 48kHz Clock 2 times bit rate 1 Source signal 0 1 Channel signal 0 Biphase mark Fig 34 Bi phase Signal Coding Channel Status Information Every
61. with how many bits per sample the Audio data have been coded Maximum value is 24Bits Follows the Emphasis field indicating whether an emphasis filter tyoe has been applied on the audio data or not Refer also to chapter Emphasis on page 18 The last statement in the line covers the Channel Status indicating what kind of audio material is transmitted Stereo 2 Chn or 1 Chn STATus Line in Consumer Format The leftmost entry of the line indicates the signal format Consumer followed by the nput Clock Please notice that the displayed value always equals one of the 3 standard sampling rates 32 0kHz 44 1kHz or 48 0kHZz NEUTRIK CORTEX ee 30 49 V54 AO10 Digital Extension for A2 User Manual Next the Category Code indicates whether the source of the received audio data is of type General CD DAT or Exprmti Follows the Emphasis field indicating whether an emphasis filter type has been applied on the audio data or not Refer also to chapter Emphasis on page 18 The last statement in the line covers the Copy Status indicating whether the incoming audio data are copy protected NoCopy or not CopyOk NEUTRIK CORTEX INSTRUMENTS V5 1 31 49 AO10 Digital Extension for A2 User Manual Analyzer INPut Lines On the bottom of the digital LC display two INPut lines provide additional information about the incoming signal In contrary to the analyzer STATus line the content of the INPut lines are not depending of the input sign

Download Pdf Manuals

Related Search

Related Contents

Troubleshooting  Flavia S350 User Manual  Ableton Manuel de Référence Version 8  

Copyright © All rights reserved. Failed to retrieve file