Hello Dave!
So if I read this right (bear with me, I'm learning), in keeping strong
signals out of its passband, it will keep the hardware AGC from activating
to eliminate "pumping"...
Correct.
But, in the same scenario, if I had a 2.7khz filter and a 200hz filter with
no strong signals, just band noise (or maybe static crash type QRN), the DSP
filter would act the same and my desired signal would come through the same
way regardless of which roofing filter I used...
Also correct. The key is if signals stronger than the desired signal
are in the roofing filter passband, and are also strong enough to
activate the hardware AGC.
And if you would permit me one more scenario. In the case of strong static
crash type QRN, in my case, either the noise blanker or noise reduction
would be able to handle the really heavy stuff. I know the hardware noise
blanker is set in front of the roofing filters and well ahead of the DSP,
therefore protecting it. I guess that statement is more of a question than a
statement.
We have pulse-suppressing AGC in addition to DSP and IF blankers. Won't
kill all the noise types, but makes a very effective arsenal against
noise. Narrow roofing filters can help in some cases here, too.
In the end, you may not often need narrow roofing filters in your
particular station's interference environment, but when you need 'em,
you need 'em :-)
73,
Lyle KK7P
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