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Re: Soundcard Decoder for UO-11?

On Mon, 15 Nov 1999, Laura Halliday wrote:

> It's perfectly straightforward FSK. Don't go for fancy stuff to start
> with; a couple of filters on the relevant frequencies is how people
> demodulated RTTY for decades.

In fact if I remember correctly, UO11 uses even simpler (in the decoding
point of view) scheme: 1200 bps with phase continuous 1200 and 2400 Hz
tones for mark and space (or other way around). The bit stream is
asynchronous ASCII, so no (HDLC) problems with that, no noticeable Doppler
because of FM..

You get even the symbol synchronization when you are locked to the
carrier. Would be very interesting to implement, if only had

Of course filters are OK, I just got carried away...:)

Good luck,


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