Making Chassaing's BPSK programs work?

Started by "B. Korst, Communications Laboratory" August 20, 2007
Greetings all,

I've been trying without success to make Chassaing's BPSK transmitter
and receiver (code from the c6713 book) work. Has anyone been able to
make these two work together? I'd really appreciate some help as I'm
trying to prepare a demo for students for this coming term.

I have not touched much of the code given with the book, except for
adjusting the levels of the outputs from both c6713dsk. The
transmitter and receiver operate at different sampling rates (I did
not touch that part). Here is the configuration I use:

Transmitter -- c6713 dsk running at 48KHz sampling rate. Input is a
very clean reading with male voice coming from an mp3 file running on
the host PC. Output is BPSK on one channel and the corresponding
carrier on the other channel. Both outputs seem fine, at about 2Vpp.

Receiver -- c6713 dsk running at 96KHz sampling rate. One input is
BPSK and the other is the carrier. Connection is done through coax.
Monitoring the debugging buffers indicates that inputs are fine.
HOWEVER, the output is junk. Since the debugging is done by filling
out large buffers, I've commented some of them out to free up the
processing. That did improve "the looks" of the output quite a bit.
However, the output is still unintelligible. I tried to see if at
least the bursts of output noise would "mimick"(sp?) the peaks from
the voice at the input, but I don't see much correlation.

Any help would be GREATLY appreciated, as steam is coming out of my
ears at this point. The code is all found on the CD accompanying
Chassaing's DSP and Applications with the c6713 and c6416DSK.

Cheers, and have a good week!