[Elecraft] K3 SSB Noise Reduction

[mark roz]

Lyle,

So, with SSB signal S9 and noise S2 with NR= F1-1 signal shouldn't drop to much??

SSB signals always drop about 3dB. Even signals SSB with good S/N.

I understand all what you are saying but how hard it would be to increase AF gain when NR is engaged?

Thanks,

Mark


--- On Fri, 3/21/08, Lyle Johnson <kk7p at wavecable.com> wrote:

> From: Lyle Johnson <kk7p at wavecable.com>
> Subject: Re: [Elecraft] K3 SSB Noise Reduction
> To: "Elecraft" <elecraft at mailman.qth.net>
> Date: Friday, March 21, 2008, 6:46 AM
> > OK, I accept what you are all saying about the gain, I
> was just 
> > postulating :)
> > I agree it does drop off, but I didn't think that
> much.
> > Anyone tried it with CONFIG:AF GAIN set LO? I
> haven't, just wondered.
> > If there was a config control for an offset, it would
> need to be based 
> > on the 4 'strenghts' I think, not on the Fx
> number, but the digit after 
> > the -
> 
> The first value you see -- the Fx -- has to do with the
> aggressiveness 
> of the filter.  The second value you see specifies the
> blend of 
> processed and unprocessed audio.
> 
> Keep in mind always that the denoiser is not a denoiser; it
> is a signal 
> enhancer.  It will act to suppress *everything* until it
> decides there 
> is some sort of signal present, then act to pass that
> signal.  The more 
> the signal appears to be a pure tone (like CW) the faster
> and more 
> decisively the algorithm acts.  The less it looks like a
> signal (noisy 
> SSB comes to mind) the slower and less decisively the
> algorithm acts.
> This is why the audio level is low to begin with.
> 
> For CW with reasonable S/N, it usually quickly builds up to
> the same 
> overall amplitude as without the NR.
> 
> For SSB with poor S/N, it builds up slowly and to a lesser
> overall 
> amplitude.
> 
> Thus, observations that the signal amplitude sometimes or
> often appears 
> reduced are correct.  The disagreements about how much it
> is reduced are 
> also correct.
> 
> It depends on the NR settings, the S/N of the signal you
> are listening 
> to at the moment, the type of signal, the IF and AF
> bandwidth...
> 
> FWIW, I usually have mine set to F1-1 or F1-2 for SSB
> operation. YMMV.
> 
> 73,
> 
> Lyle KK7P
> 
> 
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