[TenTec] Pegasus S-Meter Anomaly

[Mark Erbaugh]

Jerry

> 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 to know the algorithms used by AGC in the Pegasus.


> 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.

Good suggestion. The Pegasus interface software interface allows you to
query both the analog and digital signal levels. I might mess around with
adjusting the RF Gain / RF Attenuation based on those readings - kind of a
software controlled AGC. One drawback is that on the Pegasus there is no way
to completely disable the built in AGC.

Mark