In playing with PSK31 recently using a *very* suboptimal receiver (my
old Icom IC-706mkII) I realized how important it is to couple the
demodulation system with the the rest of the receiver. For example, I
can watch the AGC respond to unwanted signals and make the desired
signal uncopyable. So it seems to me that, in the process of
demodulating a signal the demodulator has information about the
energy in the desired signal that should be used to drive the AGC.
That implies to me that you really cannot effectively separate the
two. The "sound card plugged into the radio" approach is interesting
as a way to start but it is not the final solution.
One of the interesting features of the K3 is that PSK31 and RTTY
operation are part of the radio. Does that mean that the PSK31 and
RTTY demodulators in the K3 control the AGC so that the desired
signal and only the desired signal controls AGC?
As we come up with more and more interesting digital modulation
schemes for HF I can see the desire to closely couple the demodulator
with the rest of the receiving system. The K3 has some real
possibility here. Will it be incorporated?
How about an API to let other programmers add demodulators and couple
them to the rest of the receiver, controlling roofing filter
selection, AGC, etc.?
73 de Brian, WB6RQN
Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com
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