Decoding MSK as FSK will give you way less than optimum bit error rate
vs. noise. Unless the MSK is coming in on an FM channel you should
consider decoding it as PSK.


I did find a chip that does 2400 baud MSK. But, why should I use a PSK
method?

PSK transmits one frequency, but inverts the amplitude of the
modulation to represent a 1 (or 0).

PSK has an advantage in bandwidth, which has less noise due to the
narrower bandwidth. But, can a PSK modem actually decode MSK better?

The ap is amplitude modulated VHF and I want the best weak signal
perfirmance I can get. The AM carrier wastes some transmit power and
has a disadvantage over a single sideband supressed carrier. But, it
is still many db better than a very wasteful fm mode.

Anyway, I can't control the transmitters, so I'm stuck with AM.

Having the carrier received with the sidebands establishes the center
frequency, so the tuning in the receiver is not quite so critical. AM
is really quite practical in this case.

Can you tell me some more about decoding the signal as though it was
PSK?

Thanks,

Art