[Elecraft] APF For K3: progress report

[Wes Stewart]

Not ever having a radio with APF, I've had this nagging question since this thread began.  Does the Pitch track the center frequency of the BPF?

Wes

--- On Mon, 10/25/10, Wayne Burdick <n6kr at elecraft.com> wrote:

> From: Wayne Burdick <n6kr at elecraft.com>
> Subject: [Elecraft] APF For K3:  progress report
> To: "Roy Morris" <w4wfb at carolina.rr.com>
> Cc: elecraft at mailman.qth.net
> Date: Monday, October 25, 2010, 12:39 PM
> 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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