Re: AF Limiter (was Recommended AGC settings forseparation of signalsin CW pile-ups)

Posted by P.B. Christensen on Dec 05, 2010; 7:58pm
URL: http://elecraft.85.s1.nabble.com/Recommended-AGC-settings-for-separation-of-signals-in-CW-pile-ups-tp5804756p5805831.html

> The K3's AF Limiter is a HARD limiter that has an abrupt onset
> and causes extreme distortion.

Dave,

I don't contest (last and only one was Novice Roundup, 1973) , so I am not
familiar with the "mushiness" that's being discussed here.  However, I do
like to disengage AGC and I also find the extreme distortion to be as
objectionable as the harmful high audio level it's designed to prevent.

It may be beyond the ability of the K3's DSP, but commercial digital audio
limiters, like those found on DSP-based mastering processors, function like
a very fast analog peak limiter.  As level increases, it simply drives the
analog circuit into further limiting.

What I would like to see when the K3's AGC is OFF, is to briefly
re-establish AGC-F when the AF LIM threshold is reached and remains active
just long enough to overcome the objectionable level burst -- then it goes
back to AGC OFF.  If the K3's limiter is already trying to do this now with
brief AGC activation, it's not doing a very good job.  It would also be
helpful to have the display indicate when the AGC-F is coming active in this
mode with something like a "*" or some other special display character that
functions as a one-shot in duration.  IOW, the special character displays
for a minimum of say 0.25 sec so that the action can be seen on very brief
peaks.

Paul, W9AC

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