The notch is just another DSP filter. We (the K3) use(s) DSP filters all of
the time that are narrower than the front end filter and that remove signals or
part of signals that should not generate DSP AGC.
In the event the interfering signal is strong enough to overload the second
mixer, then the hardware AGC kicks in. No different from any other situation.
Wes N7WS
--- On Mon, 4/26/10, Joe Subich, W4TV <li...@subich.com> wrote:
> On 4/26/2010 7:30 PM, N1JM wrote:
> >
> > It's a shame. Such a sophisticated high end radio and
> no notch within the agc
> > loop.
>
> Part of the problem is that a DSP radio needs to have the
> notch after
> the AGC since part of the function of AGC is preventing the
> ADC from
> being over driven. If the notch is placed BEFORE the
> AGC detector
> the notch will cause the interfering signal to INCREASE at
> the input
> of the ADC.
>
> Yes, it would be nice for the notch to allow the receiver
> to return
> to normal gain when the interfering signal is removed but
> that would
> merely cause the HAGC to come into play.
>
> 73,
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