AVR-Chat

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>
>Thanks Tom and Mark for your responses and ideas on this matter.  I'd
>seen that pdf file before but had not thought about it in reference to
>my problem.  My mindset was more in the mode of measuring actual times
>since the bitstream timing was so "neat"; but it appears I need to do
>some breadboarding and experimenting with the DSP possibilities.
>
>Don

  A few people have made fsk modems based on measuring the zero cross of 
the audio signal. Generate an interrupt and use the capture mode on one of 
the timers to determine period.

  Most of the examples I've seen (because that's what i was interested in) 
are 1200 bps bell 202. But it may be similar enough to what you are 
attempting to give you some ideas.

  A lot of the projects are pic based , but some are avr. Also the method 
is generic enough to learn a lot from looking at the pic approaches (a 
minor sacrilege). Try googling 'avr fsk modem'.

Some links.
http://www.vfx.hu/proj/fskmodem/fskmodem_eng.html  scroll down
http://www.avrfreaks.net/index.php?module=FreaksTools&func=viewItem&item_type=tool&item_id=317
http://www.analogservices.com/vhdlmod.htm

Sorry if this is too far away from what you are looking for.

-carl