If you do it this way, how would you use it inside the 400 Hz roofing
filter, where you wanted it to diminish somewhat toward the skirts of
the roofer and then dive down. There would be no way of having this
happen inside a given roofing filter other than the narrowest as the
roofer is implied by the width setting.
Would not be of any use at all on a running frequency. This only
works as peak shaped audio to further narrow the very narrowest DSP
selectivity. Personally I've never been disappointed by the 50 Hz,
which is the cleanest narrow I've ever had in a RX.
Not at all what I had in mind. With 400 Hz bandwidth and 500 Hz
center, the passband INSIDE the roofer skirts is peaked at 500, loses
about 10 db going down to 300 and up to 700, and at 300 and 700 does
the normal roofer/DSP skirt sharp dive.
This allows me to HEAR the off-freq caller, and either shift or RIT to
center him, without the noise burden of a flat 400 Hz. Using the NR
for this in a contest masks or loses really weak signals. Not yet
discovered a setting that doesn't take away more than it gives. Never
use NR on CW at NY4A on our K3's. Lose the whisper contacts just in
the noise, any NR setting. Wouldn't even know they were there.
Perhaps for this need a special NR setting that only shapes the audio
without any cancellation at the noise level and several degrees of
slope off?
This is what I always meant by APF.
Just my .02
73, Guy.
On Mon, Oct 25, 2010 at 2:39 PM, Wayne Burdick <n...@elecraft.com> wrote:
> We might have a field-test revision of K3 code that includes APF
> sometime this week.
>
> In this test version, APF is turned on by rotating the WIDTH control
> counterclockwise past the 50-Hz setting ("BW 0.05") to the 30-Hz APF
> setting ("APF 0.03"). This eliminates the need for a menu entry or a
> new switch function. A new DSP graphic pattern shows that APF is in
> effect. SHIFT can be used, with either 10- or 50-Hz steps.
>
> The APF filter is an "IIR" (infinite impulse response) DSP filter that
> accurately emulates the equivalent analog circuitry. There's a slight
> ring to the filter, as expected. Gain is also increased when APF is
> turned on, compensating for the loss of overall signal+noise that
> occurs at this very narrow bandwidth.
>
> 73,
> Wayne
> N6KR
>
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