codec16.me

speech signal process tools

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Using the AT&T DSP32 Board D/A and A/D at 16Khz
Document Version: 1.1 6/7/89
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Normally, the D/A and A/D on the AT&T DSP32 board runs at 12Khz and
other sample rates are provided by using the DSP to do a rate conversion.
This is the case when jumper J5 on the board is set to (5,6) and the
\fBFREQ\fR part of the environment variable \fBDSPDEV\fR is set to 3072 for a board
with a 24.576Mhz oscillator or 2048 for a board with a 16.384Mhz
oscillator.   Most recent boards have the 24.576Mhz oscillator.  
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To run the board A/D and D/A at 16Khz do the following:
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Change J5 on the board from (5,6) to (3,4).  This will clock the chip at
4096Khz, for a 16Khz sample rate.
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Edit \fI/etc/dspinfo\fR and change the value of FREQ= from 3072 to
4096.  If you do not have \fI/etc/dspinfo\fR, copy it from
\fI/usr/esps/lib/waves\fR.
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Define the environment variable \fBCODEC16\fR.  It can have any value.
Something like: \fIsetenv CODEC16 1\fR is fine.
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Note that this environment variable must be defined for each user that
might use the board so it must go in their .login or .cshrc files.  It
would have been better to add this to the \fBDSPDEV\fR variable in
\fI/etc/dspinfo\fR and we'll change it to that in the next version.