[Elecraft] K3 APF

[Bill W4ZV]

wayne burdick wrote:
> 
> Joe,
> 
> If Lyle is using the same algorithm as before, and your results are as  
> indicated below (virtually a tie), I don't understand how you could be  
> hearing a "lack of ringing" in the new revision. I simply cannot hear  
> any difference myself, and I'm extremely picky. We have nearly 100  
> people testing, and only two or three have perceived a difference, so  
> given the statistical evidence, I'd suggest that background noise  
> conditions are the variable here, not the firmware. Lyle has also  
> completely reviewed the DSP implementation -- no change.
> 

I also suggested the background noise issue to Joe.  The bands have been
relatively quieter since the latest FW was released, and white noise (i.e.
galactic) does not cause the same amount of ringing as impulse noise (i.e.
lightning).  Therefore the quiescent state of APF may sound less "ringy"
than before. 

I listened to a very weak DS5USH on 80m this morning and the APF was very
effective at bringing him out of the noise.  I also did a few measurements
using the latest 5 Hz SHIFT.  The worst case attenuation (when off zerobeat
by 5 Hz) is <0.5 dB which is probably less than most ears will detect. 
However only ONE setting of SHIFT is optimum so you need to listen carefully
when adjusting.

73,  Bill

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