Posted by
Joe Subich, W4TV-4 on
Nov 01, 2010; 4:34am
URL: http://elecraft.85.s1.nabble.com/K3-APF-Adjustable-Q-tp5688670p5692836.html
Paul,
>> It seems that APF is really the inverse of the notch function.
>> Perhaps a quasi anti-LMS algorithm could be used to establish Auto
>> APF.
That's exactly the CW noise reduction algorithm. I've seen Lyle write
many times that the NR builds a low order filter around any coherent
signal in the passband. For an "auto-APF" I'm sure the issue would be
to decide *which* coherent signal to build the filter for.
73,
... Joe, W4TV
On 10/31/2010 10:54 PM, Paul Christensen wrote:
>> "In the RTTY world, "twin peak filters" available in many rigs often give
>> better results only because many software demodulators do not come with
>> matched filters. "
>
> Chen,
>
> So far, nobody has discussed the possibility of an "Auto APF" feature that
> functions much like Auto Notch, but would automatically track the peaking
> frequency in the event RIT was engaged, for example. Within limits, such a
> function would allow for hands free APF as the received pitch is changed by
> the operator. Consider an automatic DSP notch filter that uses the LMS
> algorithm. It seems that APF is really the inverse of the notch function.
> Perhaps a quasi anti-LMS algorithm could be used to establish Auto APF.
> Does such an algorithm now exit by name?
>
> Paul, W9AC
>
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