Application Note (Vol.5_1 - 02_1990)
Contents
1. 2 e e 2 s 3 2 H H 3 3 30 o pipes Erpse ee PATATET _ _ nina bem oe ote de FSB PORTO OE vb rA nereneng e s H i i 3 3 H 3 i s s a H i00 0 BRO ONT Ne ER RS ERNE SAMS SAER VASI POETO 8 3 3 gt 3 3 i H 3 e r 2 ry H 3 H ry p 2 H 2 a H i i H i 3 i 0 a r a a a atara EN a RE ara a E E Ea ons Bea ane opaonnsnn H 3 2 H 3 2 3 3 3 Hi t e a a a s s 2 t s 2 H s 2 rf H s 2 i i i 20 0 aeereesnnscenies fren eee an a ee a ee Ce HA 2 ry a 2 3 2 3 4 d a Q a 2 x e e a 3 0 3 fesenmenertarmmcte 130 se soso bse neuen sebssss0s19sees tas 0s104n pees egOOSDOTOAONNGTAOLODEEALETOSEHORRDSEDESE geen o 2 s H 2 3 3 3 ei H 2 t e i z H H i gt 18 140 0 i BTR fe tron os aoteQneveHoRSTOetT DenbeEh FEEsOPsDENe easabinansancasasonsteeoeseasaneneenien 3 3 2 H 2 e 3 2 f H A 3 H i s Hi 2 i 7 gt a 3 A i i i f Pe 7 3 i i 3 150 0 frorcecs dD dssecsesgroacerss TETI ON CT ERL TT TO i EE TLSE sos 2s hesessreanazea sten LAA aai rf h 5 4 3 3 H 3 3 z H H 2 H e H e a H s z 2 AEN N AAIR 160 0 mn ern ee 0 0 Aok 400K 600K book 10 0k 12 0k 140k 160k 18 0 20 0 Residual Distorion of System One 256 Times on t Save ter Second and third harmonics are vis2. by the latest DSP program revisions Most recently developed high resolution 16 bit and more A D and D A converters have serial rather than parallel connections The System One Dual Domain serial port can be easily interfaced to these converters The rear panel parallel input and output ports are casily interfaced to parallel connection con verters and to other DSP units Two Dither Types Rectangular probability distribution dither has been added as a user selection for digitally generated sig nals in addition to the original triangular probability distribution dither Each has its own advantages in terms of S N degradation versus reduction of noise modulation effects and test condition setup data Each data point in the test adds 13 bytes except that the first point adds 20 bytes to the file size It does not matter whether both DATA 1 and DATA 2 are in use since space is reserved for both In contrast a DAT file con tains a byte for every character including each space which separates the data values A zero data DAT file is 64 ytes and every data point adds 63 bytes Again file size does not depend upon whether DATA 2 is in use So a little math says a DAT file length is DAT 64 63n bytes and a TST file length is approximately TST 1660 13n bytes You can thus determine that a DAT file is smaller for 32 data points or less and a TST file is smaller for more than 32 points However PC compatible computers
3. display When you gave the COMPUTE NORMALIZE instructions here is what S1 EXE did 1 Converted your 0 dB target into a value in the base unit Volts 2 Obtained the original data value at 1 kHz in the base unit Volts If the data does not contain a point exactly at the re quested horizontal SOURCE 1 value it will interpolate between the two horizon tal points which bracket that value If there is no data bracketing the value it will display an error message 3 Divided the user entered target value by the data value 4 Multiplied every data point in base units in the file by the result of the division in step 3 So what looks like a simple dB addition or subtrac tion with amplitude data is really obtained by division and multiplication Now you can see why this won t work with phase data Let s say the original phase data varied between 20 and 70 degrees across the audio band with a 5 de gree value at 1 kHz You wanted to normalize the phase curve to 0 degrees at 1 kHz COMPUTE NORMALIZE will divide your 0 degree target by the 5 degree actual data value get 0 for the answer multiply all data points by 0 and you re surprised Or if you asked for a 10 degree target the division quotient will be 2 and the resulting phase data after multiplication will vary between ie and 140 degrees a completely different curve shape The solution for phase normalization with 1 EXE is use of the COMPUTE DELT
4. don t save just the exact file size Hard disks on most PC compatibles are divided into 2k actually 2048 byte sectors Save a one byte file or a 2048 byte file and either will occupy a 2048 byte sector on the hard disk So here is how it works out for 29 data points or less both DAT and TST files are less than 2048 bytes and will oc cupy a single 2k sector For 30 or 31 data points the DAT file will still fit in one 2k sector while the TST file occupies two sectors At 32 points the DAT file also takes two sectors and at 33 points and up th TST file will be smaller than the DAT file Finally the big advantage of SAVE TEST rather than SAVE DATA is not just minimal disk space but the fact that the data is much less ambiguous since all the test conditions are saved with it A DAT file in dBr units gives you no idea what the dBr reference was A DAT file in dBm can t tell you what dBm impedance reference value was in use You can t tell from a DAT file what the gener ator amplitude was during a frequency sweep which detector and filters were in use in the analyzer or whether REGULATION or EQSINE modes were used All that information is explicit in eda file format directly readable in PANEL mode So why is there a SAVE DATA command at all Purely for one reason data transfer to other software programs System One s DAT file fits a standard format throughout PC software with its ASCII characters comma
5. just measured frequency response of a CD player using a test disc The left channel data graphed as DATA 1 goes exactly through zero dB at 1 kHz be cause you pressed the lt F4 gt key while a 1 kHz sig nal was playing just before the response sweep But the right channel DATA 2 is above or below zero depending upon the channel imbalance of the CD player So you use lt Esc gt to go to the menu select COMPUTE NORMALIZE and enter the numerical arguments 2 1k 0 meaning normalize DATA 2 do the normalization at the horizontal value of 1 kHz and push the data up or down so that it goes through the 0 dB target at the horizontal value of 1 kHz Now you can press lt F7 gt for a re graph and both DATA 1 and DATA 2 nicely go through 0 dB at 1 kHz If you ever tty COMPUTE NORMALIZE with phase data you ll be disappointed The data will go through the value you specify at the horizontal point you specify but the overall phase curve shape will change with surprises at all other horizontal values Why this happens and what to do instead is the sub ject of this article COMPUTE NORMALIZE works by dividing and multiplying and it works on data in the base unit In all amplitude measurements the base unit is Volts In phase measurements the base unit is degrees When you made your CD player response measurement graphed in dBr or any other decibel unit S1 EXE software converts the base unit volt age numbers to dB for
6. A utility COM PUTE DELTA is a subtraction utility and it works in the units currently displayed For the case just described of phase normalization by 5 degrees you ll need to create a single point file with the value 5 degrees and save it to disk To do this load or create a TST file with SOURCE 1 as a fre quency parameter such as GEN FREQ and with DATA 1 selected as ANLR PHASE or LVF 1 PHASE with 1 60 or earlier software in degrees Then use lt Esc gt EDIT DATA to enter the data editor Leave the top header row of text intact Hz deg OFF but delete any data below that line by use of the lt F6 gt key Then enter any frequency the value won t matter in the first column a comma and 5 or the phase offset value you need in the second column The result will look like this Hz deg OFF 100 5 It s not important that the numbers line up beneath the headers but the comma is critical as a column delimiter Now use lt Esc gt to get back to the menu then ee TEST and supply a file name such as SDEG Now it s time to re load the phase vs frequency test whose data you wanted to move down by 5 degrees Use lt F7 gt to graph it to be sure it s the file you want Then lt Esc gt NAMES DELTA and use the cursor to select your file name SDEG TST in this example followed by lt Enter gt to make the selec tion Now use COMPUTE DELTA The software will try to interpolate the DELTA file data for every frequen
7. Volume 5 Number 1 February 1990 Yes it s finally another issue of AUDIO TST No you probably didn t miss any issues this is the first since March 1989 Other priorities involved in the introduction of the new DSP modules unfortunately The new System One DSP and System One Dual Domain units began shipments in October 1989 They have already gained wide acceptance with well over 100 units having been shipped as of January Many of the early applications are in A D and D A converter testing digital mixing console and digital routing switcher tests measuring digital audio channels of professional VTRs and main tenance of all types of audio equipment in broadcast and recording studio environments Original Features System One DSP Earlier AUDIO TST Newsletter articles gave an idea of some of the basic DSP features In System One DSP these include FFT spectrum analysis waveform display in digital storage oscilloscope mode and individual harmonic analysis via a sharp digital filter tracking the incoming signal or any har monic from second through ninth Original Features System One Dual Domain System One Dual Domain includes those same fea tures plus generation and analysis of digital audio signals directly in several formats The digital domain analyzer includes a frequency counter plus two independent amplitude meters with RMS detec tors One meter also has the ability to insert high pass steerable band
8. cy in your phase sweep but since the DELTA file only contains one value it will come up with 5 degrees as the result of each interpola tion So it will subtract 5 degrees from every data point Use lt F7 gt to re graph the data and you should find your original phase curve shape but now offset vertically to go through the desired target
9. d and furnish ing a file name then copies that graphics display list disk file to your new name The GDL file created by SAVE GRAPHICS will contain the last graph displayed If for example you have just started S1 EXE software loaded a test but not displayed the graph and immediately used SAVE GRAPHICS the GDL file will consist of the Audio Precision logo seen each time the software starts To load a test and immediately send the graph to a GDL file you must first use lt F7 gt or the equivalent RUN GRAPH menu command to graphically display the data before using SAVE GRAPHICS The new graphics information is writ ten into the graphics file replacing whatever was previously in that file whenever an lt F7 gt or lt F9 gt key operation causes a graph to be displayed Version 2 004 Software Up Compute grade More than 1 500 copies of version 2 00A of S1 EXE were shipped to U S customers and International Distributors between January 31 and February 3 1990 This free upgrade consists of a new 306 page User s Manual and four diskettes The four disket tes include the S1 EXE v2 00A program diskette a Tests and Procedures diskette a Performance Check diskette and a Utility diskette Only one version of S1 EXE is now required rather than the separate CGA and Hercules versions of previous revisions S1 EXE now automatically determines the type of computer display system and installs itself according l
10. delimiters between columns and a carriage return line feed at the end of every row This format can be directly imported into Lotus 1 2 3 as a PRN file and into most other spread sheet programs into BASIC programs or into almost any other software environment Even if you do lan to eventually export the data into Lotus 1 2 3 that still doesn t mean you must SAVE DATA at the end of the test You can always use the more explicit and usually more efficient SAVE TEST command then at any later time LOAD TEST then SAVE DATA In the interim your infor mation will usually occupy less space on the disk and won t run the risk of becoming orphan data where you have the numbers but no longer remem ber just what they mean ers Sales Staff Facility Growth Thanks to the continuing support of our users Audio Precision has just completed a very success ful year in 1989 Our sales grew 44 over 1988 or ders were up by 40 55 of 1989 orders came from International customers and 45 from U S domestic customers The new DSP modules for Sys tem One were a substantial contributor to the order and sales growth That increased production also had its impact on our Staff and facilities Audio Precision now consists of 22 full time employees plus some part time help and our continuing sub contracted circuit board assemb ly In September 1989 we expanded into additional space at our same location This expansion in vol
11. ewed with almost any editor or the DOS TYPE command The SAVE TEST command saves the test data plus complete control information for System One hardware at the time of the test generator level and impedance analyzer function detector type fil ter selections settling panel parameters REGULA TION mode parameters etc SAVE TEST also saves any comments you had in the EDIT COM MENTS buffer at the time of saving A TST file is a binary file and cannot be usefully examined with an editor From those descriptions it is easy to understand why some users select SAVE DATA since it seems it might be more economical of disk space How ever an analysis of structure and size of the two file types shows in terms of actual space used on a typi cal hard disk this is almost never true The size of a TST file with no data no comments and the standard AUDIO PRECISION graph title is 1 660 bytes with version 2 00A software That 1 660 bytes principally consists of all the instrument AES EBU Status Bytes The professional AES EBU digital audio format and the similar SPDIF and EIAJ consumer formats con tain defined status bytes in addition to the audio sig nal These bytes control de emphasis copy prohibi tion sample rate etc The System One Dual Domain user may set those bytes as he or she wishes on digital output signals in those formats General Purpose Serial Port A rear panel serial input output port has been enabled
12. ible at about 120 and 130 dB and the noise floor at 140 to 145 dB obscures most lower amplitude harmonics The second figure is the result of 256 repeated ac quisitions FFTs and averaging the FFTs The noise floor has been reduced to 150 dB allowing resolu tion of distortion products such as the 9th harmonic at 147 dB This averaging mode also has interest ing potential with voice and music program material producing a graph of average spectral ener gy distribution over periods of up to five minutes House Sync Installations with more than one digital audio device typically use a house sync bus as an external refer ence clock to assure that all digital signals are synchronous The DSP module s rear panel external sync input connector has been enabled by the latest DSP program revisions to provide house sync capability for System One Dual Domain generated digital signals This external sync capability also permits generating signals at the 44 056 kHz rate used in NTSC video related digital audio applica tions The SAVE DATA command of S1 EXE software converts any data presently in memory into ASCII values then saves that ASCII file to disk under the name you supply The results might look like this for a short four point three step sweep Hz deg dBu 20 10 1750002 4 52589495 200 6 0999999 7 25721348 2000 2 0999999 7 54252103 19999 916 19 6000004 6 84135187 As an ASCII file the DAT file can be vi
13. mode right figure above makes it easy to see and measure the amount of overshoot and the release time of the compressor Before and After Tests Signals can be acquired into the two DSP channels at different times then displayed as two simul taneous FFT spectra or waveforms in split screen fashion or overlaid With the new SAVE WAVEFORM and LOAD WAVEFORM capability these signals can be acquired months or years apart Graphics cursors permit easy simultaneous examina tion of both channels to compare performance of two supposedly identical units the same unit with and without dither a prototype before and after design changes etc Increased Spectrum Averaging FFTGEN DSP one of the two furnished FFT programs includes a mode for repeated signal ac quisitions FFTs and transform averaging before dis play Up to 1 024 acquisitions and averages may now be selected Averaging has two advantages One is to effectively reduce noise components making coherent signals stand out more clearly The two figures below show the residual distortion of the analog generator and analyzer of a System One in THD N mode at one kHz The first figure was a single acquisition and FFT The fundamental is attenuated about 123 dB by the analog notch fil AUDIO PRECISION 256 ANPL dB vs FREQ Hz 05 FEB 90 16 59 57 B0 00 a a COIT Te AeA eT r rr SO OUCOEODISNEO RIES ADEEDSESAHRE BODO SERENE R EROS H 3 3 f HW 3 2 s rf 2 s H s r a a
14. n FFT pro PRECISION MONOTONE ANPL XFS us TIMECsec 30 JAN 90 19 37 06 ee ee po a Sroseocesnensvvesrenssnneesoed e a AUDIO 00040 3 s s H 8 00030 ATE TE scecneottarnaesovanceosceeee e e e E j4 3 e a i 3 H H e e t s e e 00020 pre sodara peer beeedsae pess 00010 fomennfredpomfesefneef enon se Eila eee A A s s 3 H boboni T ada se ossoeeavosssesdrononoopasossoartaopesprpoegtionoestogsopostoarean jon i s J DOT sh orrfesosiocsn so jens ones wii aii I 4 TTY a e 2 suaeesnoeeaeesseovereeseonsarenrensseseso director ones ecenaguagsanronsorecesonsrnesatensemiennaneere sere segrenioseseeg reese ae 2 e H 3 e H i 0 0 gag pai t ry p3 pr prer sea a 3 yaad ee 0002 per jesto or Hi T E ae i i boo i i i e s s e kad ae 0 nnp vu Leah AUDIO PRECISION COMP LIN ARPL U amp AMP2 U vs TIME sec 06 FEB 30 15 30 33 gt ome E tatoos tinee r A aane aaa E EIEE ETT KITTE ETITI TE RETETE m DELTEI PIDE t jonpersenese aie ee H H H H t t 3 i Ap i 3 seosnaseesees mee Srsosesssenersactonseses sranognsaneasacsarearensencensecsees aaseesgoseerescaneosee 3 toad RARU s 3 tb z GH RRE EIERE sebsdateetercacsssansecsessaiessearentnssssresserees areenseseusneroreses earsarearaveeorocea a e H z 3 600W Daa use b ee ann eee See senfare ee spo
15. n enone eve sso H2 000 i 3 8001 Prercasoscessondgpie Pyro 5400 es Berens epee a ea jon seser a ARAE sje eee engeesenenn sabesco sev oringa ihh as Saas PE 000 3 i ae oa Siss seers aanenanaa shoo mien demene erasejasesianane eii 000 Snina i 1 2003 pone seasonal 0 0 1 400 dl i iy i 600 sesmaninansidh SES Compressor Output upper trace with Sine Burst Input lower trace Conventional Linear Vertical Display gram in waveform display mode The staircase sig nal continuously repeats across the 4 LSBs 16 lowest states of the digital output This signal is pe at similar to the track 21 signal on the CBS est CD Waveform Save and Load Features have been incorporated into S1 EXE and both FFT programs to permit up loading entire ac quired waveforms from the DSP to computer disk and later down loading of disk stored waveforms to the DSP for further analysis or display These fea tures also permit transfer of waveforms from one FFT program to the other or combination of two waveforms acquired at different times or places into the two DSP channels for simultaneous display Waveform Envelope Mode A new MAXIMUM waveform display mode has been added which sends to the PC for display the ab solute value of the greatest positive or negative sig nal amplitude in each set of samples examined Since absolute values are always positive this mode permits signal display in LOG Volts or a dB uni
16. of a nearly full hard disk or One with badly fragmented files If a simple SAVE TEST operation requires several seconds of hard disk activity check to be sure that you have an ade quate number of buffers Check by using S1 EXE s EDIT COMMENTS facility an editor or the DOS TYPE command to examine your CONFIG SYS file found in the root CA directory of your hard disk or on your bootable DOS diskette If there is no BUFFERS statement or no CONFIG SYS file you are operating with the default two or three buf ers An optimum value for S1 EXE and many other programs is about 10 15 More than 20 buffers may actually begin to slow the system Each buffer will reduce the amount of memory available to other ap plications by 528 bytes To set buffers to the desired value simply include a command such as BUFFERS 10 in your CONFIG SYS file You can edit your CON FIG SYS file or create one if none exists on your comput using the EDIT COMMENTS facility of 1 EXE The version 2 00A User s Manual should have been more explicit in the HARD COPY chapter describ ing use of the new SAVE GRAPHICS command plus PLOT EXE or POST EXE to obtain high resolu tion graphs from plotters and laser printers When S1 EXE software has been started with the G command line option to enable graphics reporting a graphics display list called APLAST GDL is created on disk each time a graph is displayed Using the SAVE GRAPHICS comman
17. oroseae 150 0 5 iene i 3 H H i baie 0 2 00k 4 00k 6 00k 8 00k 10 0k 12 0k 14 0k 16 0k 18 0k 20 0k Residual Distortion Spectrum of System One oo COMP LOG ARPL dBr amp AMP2 dBU vs TINECsec 06 FEB 30 10 A D prarmoserorianapr a a Ei PMO ONDHSS COED S OOII D ADALE ppeeneressesng II gtaesneceoresioegeetetecsssepocegepoaesoreesces y soraeranenere a aeesreness v4 2 H 3 s H 3 i H s e AA EE RA EAA AN ani aaan a E A H H 3 28 gt 1 PoE i po i ji H i H 26 3 4 3 pa Biveseer Gescsncrersnsessns escatovoneraesoveseesspusancscsesegcaenansssssregesatenresensssesesepeunssieassertes 3 ean i p t r 33 ts H 3 H H H te 2s 33 earsarcorsarabrensecrecssstmsbecessaacascns aged H H 8 3 3 3 23 H ssevsesdooe saraviestoGersererrerrarresostosa H 7 a 2 e 7 lane occpecancsicocea Hy H l 3 H 3 H ie erens neadernitoeit weber E a renens gt sen meme Dea aai s i is 3 zi esnmgomreusmen parsoners g 0 i He aibi H r3 HE Same Waveforms MAXIMUM Waveform Display Mode Log Vertical Display beginning of the burst and the gain recovery follow ing the burst are visible but not easily quantifiable The dB display permitted by MAXIMUM
18. pass or bandreject or noise fil ters and to select a quasi peak detector System One Dual Domain can thus measure frequency response THD N versus frequency or amplitude linearity and deviation from perfect linearity weighted or unweighted noise and S N ratio quan tization distortion crosstalk and frequency in any of the four possible combinations of analog and digital inputs and outputs prevented publishing other issues later in 1989 We plan to keep AUDIO TST coming at a more regular rate in the future Several features have been added or enhanced since the last AUDIO TST newsletter report The remainder of this article describes additional capabilities being shipped as of February 1 1990 Bit Error Testing Program BITTEST DSP is a bit error test program useful in testing digital interface circuitry digital transmission paths and digital storage media It both generates and analyzes walking bit patterns pseudorandom sig nals or a constant amplitude digital DC signal with any amount of time delay permissible between generator and analyzer Received bit errors can be displayed in real time maximum or totalize modes The bit error test program additionally generates a sine wave and a low amplitude staircase ramp sig nal though it presently lacks the ability to analyze errors with these last two signals The figure below shows the staircase signal as acquired on a second System One Dual Domain unit using a
19. t to show wide dynamic range signals such as behavior of compressors with tone burst stimulus Both figures at the top of this page show the BUR GEN waveform stimulus to a compressor lower trace and the output of the compressor upper trace The stimulus waveform amplitude between bursts is set to 20 dB As viewed on any oscilloscope or in the normal waveform display mode of the FFT programs left figure above the overshoot at the AUDIO PRECISION 1 AMPL dB vs FREQ Hz 05 FER 30 16 90 16 55 14 SADILOSEOOSEAILASAOIQIRTIOtOBELPIOSSOLtOCIOEIDIEQIOOSOtIE MIREI OIEDEOIHO 040I HAIEOSS0III 004A FESOEDSESEGIID CH SIESS HOI sMOHE SHED ICOs Oreo eetaT rA 3 Hy t t pi 3 3 p 3 sees seman Ale fp d poo bo P H 3 H H H 100 n 0 D a aa ARRE ET Ea LEE EEE a T aesecaroscoenssas oroassonososrereossoraeacasoeesosSareasoseoor 054000910309 evoaconcosearen sbssecsensasessorseesassascatessoese s i i i i 1i0 0 mereavanqueesccessnsonscvanienveniorvesconsarorsestasesneenoeseneecoionran son areseeaseesseconvessetaerencesises osso ron torrone oresrerear areeni oosovseenerosioeres os n i j 3 H i i i i 2 H H H H H 120 0 ensnacenses fuceee ne a aa Sremrescraeess oreefaccorsnccncansnne a eerenccessonscses Gpesoeanscneseesard i i i 130 0 it i 3 f i H r a a aa cians a eeniaaa AUL 3 3 3 HENN i i i i i i i i 140 0 Ha i H a Ey hi zal 3 py A t t fad bs H s i H H i F froocsssscpssaserfhesarser
20. ved doubling space to 12 000 square feet 1 115 Square meters Further expansion of the Engineer ing staff is planned in 1990 in order to increase our rate of nc product introduction Manufacturing staff will increase as demanded by increases in order rate test us to see if we can keep up m roving Sneed Via Buffers Command Most users realize that the operating speed of Sys tem One depends upon their PC s processor type Clock rate and presence of a math co processor An AT compatible 80286 based may typically run tests and procedures 30 40 faster than a PC com patible 8088 The math co processor 8087 80287 etc has a major effect in dB conversion log Computations and display speed five to ten times improvement in the speed of an lt F7 gt re graph may result from use of the co processor Not everyone realizes that a standard DOS con figuration facility called BUFFERS if not properly used may slow down System One testing by a mar gin of two to one or worse A BUFFER is a section of memory set aside for disk operations When a disk read or write is called for DOS checks to see if the information is already in a buffer if so no disk access is needed The default value for number of BUFFERS is only two or three which is quite inade quate for optimum operating speed with S1EXE software The symptom of an inadequate number of buffers is very slow access operation to a hard disk similar to the operation
21. y It supports the full resolution and larger color palettes of VGA and EGA systems in addition to Hercules and CGA Owners of System One DSP and System One Dual Domain will also receive a version 5 DSP program diskette and the 72 page DSP User s Manual In addition to new high resolution multi color dis play capability v2 00A includes user control of print screen graph height and width HP LaserJet printer support portrait or landscape mode graphs graphs to HPGL pen plotters multi color and Laser Jet or PostScript laser plotters with resolution un limited by the computer display system graphics cursors sub procedures and a GO TO command a procedure feature permitting menus within proce dures for user test type selection an averaging mode for noise reduction REGULATION by varying gen erator frequency improved MAXIMUM and MINI MUM algorithms in REGULATION mode im proved status display on the HELP screen improved memory usage options log graph end points of 3 and 8 in addition to 1 2 and 5 and a variety of other improvements If you haven t received your free upgrade yet con tact Audio Precision or your Audio Precision Dis tributor Comput e Delta Why doesn t COMPUTE NORMALIZE work for phase data The COMPUTE NORMALIZE menu utility is high ly useful to push amplitude data up or down on a graph so that it goes through a point you specify Here is a common applications example you have
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