On 4/12/2013 8:14 AM, Albert Cahalan wrote:
> If it only supports mono, you're wasting power and space.
I am missing the point, please restate.
> The low-pass filter should be passing everything below about 22.05 or
> 24 kHz, right? Even an imperfect filter should be fine.
Oh. Kristoff, is the modem not using Manchester encoding?
> The comment about the modem output itself driving the circuit is interesting.
> That would seem to take away any ability to adjust relative timing, but maybe
> there could be a preamble.
Several operators are currently using VOX to key their radios, which is
effectively the same thing. The way the codec is built there is fast
clock recovery, so there isn't really a need for a preamble - you just
lose a little audio at the start. If Kristoff's implementation puts much
info in a header, that would be a problem. I like the way the HF codec
sends data alongside codec audio, repeatedly. Possibly we need to add a
checksum or FEC to that. It would slow it down but perhaps not too much.
> USB adds latency.
I suspect that the USB to serial adapter is the slowest piece in the
chain. The rest of USB usually runs a lot faster than we need.
Thanks
Bruce
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