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Hello All, Does anyone know where I can find the tool/data of the modified answer tone (ANSam) with phase-reversal specified in ITU-T V.8? I'm currently working on a tone disabler which is a part of the echo canceller and I need the ANSam to test it. Thanks, Sheng Mou _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp |
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phase-reversed ANSam tone
Started by ●August 29, 2001
Reply by ●August 30, 20012001-08-30
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Sheng Mou: It is very easy to produce the necessary data. You can use Mathcad, Matlab or a tool like CoolEdit to create a number of different signals quickly. The specs for ANSam are 2100 Hz with 20 % AM modulation at 15 Hz. The phase reversals should occur at 450 ms intervals. The standard only guarantees you will see two reversals at the detector. ansam(n) = (1-0.2*sin(2*PI*n*15/FS))*sin(2*PI*2100*n/FS + PI*if(mod(int(n/(0.450*FS)),2)) If you are really stuck, I can make these signals for you and send them directly to you as attachments to your email. You need to specify sampling frequency you expect to use and the deviations you want to test over. Most programs will absorb text formatted data. You can add noise yourself to test against various SNRs and adjust the levels to account for sensitivity. Good luck David Shaw --- In echocancel@y..., "Sheng Mou" <sheng_mou@h...> wrote: > Hello All, > > Does anyone know where I can find the tool/data of the modified answer tone > (ANSam) with phase-reversal specified in ITU-T V.8? I'm currently working > on a tone disabler which is a part of the echo canceller and I need the > ANSam to test it. > > Thanks, > Sheng Mou > > _________________________________________________________________ > Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp |
Reply by ●August 30, 20012001-08-30
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If you want the Matlab code, it is k = (0:1/FS:(T/1000)-1/FS)'; Y = (1 - 0.2*sin(2*pi*k*15)).*sin(2*pi*2100*k + pi*(mod(fix(k/0.450),2))); T = length of signal in milliseconds, FS is sample rate in Hertz wrote: > > Sheng Mou: > > It is very easy to produce the necessary data. > You can use Mathcad, Matlab or a tool like CoolEdit > to create a number of different signals quickly. > The specs for ANSam are 2100 Hz with 20 % AM > modulation at 15 Hz. The phase reversals should > occur at 450 ms intervals. The standard only > guarantees you will see two reversals at the detector. > > ansam(n) = (1-0.2*sin(2*PI*n*15/FS))*sin(2*PI*2100*n/FS > + PI*if(mod(int(n/(0.450*FS)),2)) > |
