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Prototype FEC telemetry encoder/decoder released



I have released my prototype encoder/modulator and demodulator/decoder
for the FEC-coded format I'm proposing for AO-40 telemetry.

The encoder/modulator takes user data on standard input and produces
signed 16-bit linear PCM samples on standard output that can be played
out through a standard PC sound interface. The demodulator/decoder
reads the same PCM sample stream on standard input and produces
decoded data on standard output, with optional information sent to
standard error.

Two additional programs are provided for testing.  They operate on the
modulated PCM sample stream by adding a specified amount of noise and
(optionally) deep sinusoidal fading.

I developed it on a Pentium-III and a Pentium 4 running Linux, but it
should compile and run on any Linux or other UNIX-like system with GCC
(the GNU C compiler). A Intel/AMD CPU with MMX, SSE or SSE2 support is
recommended to take advantage of my accelerated DSP and Viterbi
library routines, but is not absolutely required.

The source is in Linux/UNIX "tarball" format and includes a README
file.  The URL is

http://people.qualcomm.com/karn/ao40/ao40prototype-1.0.tar.gz

Other information, including the coding specification, a reference
encoder and demo files, continue to be available at

http://people.qualcomm.com/karn/ao40/

Please note that this package is a *prototype* intended to test and
demonstrate the coded format and demodulation and decoding techniques
and as a reference for developers interested in incorporating this
format into telemetry decoding and communication programs that have
their own user interfaces. It is not intended to be a turnkey
application.

Comments and suggestions are invited.

Phil





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