[TenTec] Pegasus S-Meter Anomaly

[Dr. Gerald N. Johnson, electrical engineer]

It would be logical to me for the RF AGC to be fast while the audio AGC
was slow and for the RF AGC to be faster on strong signals to protect
the A/D better. The DSP always works better with the strongest signal
that doesn't clip going in. So when there is a lot of RF gain reduction,
its expedient to drop the AGC rapidly so that a weak signal following
the strong signal isn't lost in digitizing noise. Yet there still has to
be a fast attack to protect the A/D from being driven into clipping.
When you over drive the A/D the clipping is BRICKWALL hard.

It would be nice if the displayed AGC were a smart combination of RF and
audio AGC with the result slowed to the audio time constant. You could
probably do that in software based on AGC reading. E.g. integrate the
values with a couple seconds time constant, especially above the signal
level that you see showing syllabic variations.

73, Jerry, K0CQ

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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.