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Re: Re: UO-2 Telemetry Decoder Software



Clive Wallis <clivew@zetnet.co.uk> wrote:

>AFAIK there isn't any suitable sound card software for decoding this
>bird. It's something that I've been interested in,  and there is no
>real reason why a suitable program could not be written. Many similar
>applications have already been written.  Unfortunately the sound card
>is very very complicated, and difficult to program.  I have looked at
>some code (in C ), for putting the received bits into memory. Just to
>complile and try it out will be a major task for me!  If I do ever
>get round to this task, it is likely to be a DOS program.  A Windows
>version adds even more difficulties!...

The Henny Youngman School of Programming provides the answer:

   "Windows makes it difficult to use the sound card!"

   "Then don't use Windows."

Sound card access under other operating systems is easy.
Under Linux (and other OSs with similar sound drivers)
you open() the device (usually /dev/dsp), use ioctl() to
configure it (sample rate, sample size, etc.), use read()
to get the samples, and then have your way with them.

The actual signal is FSK, and you can demodulate it any
way you wish. The bit clock is synchronous with the tones,
which is handy.

It all works fine. My current Interesting Application is
one that detects ionospheric chirp sounders, producing
pieces of paper with wavy lines on them. Side question
for you VK folks: what is the bird that sounds like these
things?

Laura Halliday VE7LDH     "Que les nuages soient notre
Grid: CN89mg               pied a terre..."
                                   - Hospital/Shafte

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