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RE: RE: 38k4 Operation with FT 847



Robert McGwier said:
> I believe that the DSP2232 MIGHT have sufficient A/D bandwidth
> but not the SCAF bandwidth to do the 38400 bps modem.  I will check. If
> I can change the sample clock to 4x what it is now, and do a single
> channel version or if I can modify the code to work at 2x, I will. This
> will be the UO22 modem (with equalizer) modified to run 4
> times as fast or a rework to run at 2x or 1x by reducing the number of
> samples per baud.  I am not certain it will work. It has been
> Sooooooo long since I looked at this stuff, I can no longer even
> remember if it is possible to set the filter chips fast enough.
> If not, then the only way will be to BYPASS the filter chips,
> providing your own external filtering (which we should have
> provided for in ancient days).  That said,  I already know that
> we have sufficient A/D bandwidth.  That is because we are
> oversampling for the 9600 bps modem by a factor of 4.  This can
> be done with a 2x demodulator and a modification to the clock
> recover and fractionally spaced equalizer.

It's been done for the DSP56002EVM before, see the 38k4.zip file at:

http://www.qsl.net/eb3gfv/tmsatinfo/

73
Mike W4LNA
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