[Elecraft] K3 APF

[Paul Christensen]

> "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