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Software demodulator for ACE spacecraft



Late last year I wrote a demodulator and decoder program in C for the
real-time solar wind data from the ACE spacecraft. I did this for NOAA
so they could afford to add enough ground stations to provide 24hr/day
coverage (the hardware decoders they had been using cost something
like $50K each!)

I've put this up on my web page for people to look at. The telemetry
format follows the CCSDS standards, which includes some pretty strong
forward error correction (interleaved concatenated Reed-Solomon and
Viterbi-decoded convolutional). The demodulator as-is is pretty
specific to ACE, and it assumes there's a PSK receiver tracking the
residual carrier and providing baseband audio to the PC's sound
card. I plan a separate PSK receiver program that would do this same
function in software on an "offset carrier" signal like that provided
by a SSB receiver (assuming it can be tuned to keep the signal
somewhere inside the receiver passband).

I'd like to get people experimenting with these techniques on our analog
transponders, as I think they have a lot of promise. AO-10 would be
a good challenge.

See http://people.qualcomm.com/karn/code/acedemod/

--Phil
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