At 01:17 PM 11/23/2004 -0000, you wrote:
Has anyone got anywhere with developing soundcard based MSK ? Surely
that is
the next obvious move on LF where switch mode PAs rule and a linear PA
isn't a
realistic option for high powers, knocking PSK31 on the head.
I gave up on it.
Most of all, I found it very difficult to code efficiently.
It's quite sensitive to small frequency errors, and I recall
running some tests which satisfied me the MSK error rate was
actually *worse* than the BPSK we were using. The emphasis
here is trying to copy things I couldn't copy before, not
on conserving bandwidth. Yes, MSK is a great bandwidth-saver,
but the 160-190 Khz North American unlicensed band is not used
too much and we don't yet have an amateur allocation. Maybe
if we ever get 137 Khz I'll take it up again. It may be easier
to implement with GPS-disciplined timing and frequency control.
If I can make some time I'll look into it from that perspective.
Bill
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