[Elecraft] k3 NR Audio level increase

[Joe Subich, W4TV]

> So where's the problem? Everything seems to be working 
> properly.  With a high THR and low SLP, louder signals 
> are LOUD and NR just helps make it more obvious because 
> there's not so much noise to distract your hearing. 

It's not working as it should ... there should be no volume 
change when engaging NR.  Noise reduction should work on the 
audio AFTER AGC.  If anything, the test results below should 
show a very slight drop with NR due to the removal of the 
unwanted (broadband) components but the peak level should 
not change. 

This NR problem is the flip side of the issue with the notch 
filter ... Notch is working AFTER the AGC where it should 
work before AGC while NR is working before the AGC where it 
should work AFTER the AGC. 

73, 

   ... Joe, W4TV 
 



> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Steve Ellington
> Sent: Saturday, April 25, 2009 2:00 PM
> To: Joe Planisky; W7TEA
> Cc: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] k3 NR Audio level increase
> 
> 
> So where's the problem? Everything seems to be working 
> properly.  With a 
> high THR and low SLP, louder signals are LOUD and NR just 
> helps make it more 
> obvious because there's not so much noise to distract your hearing. 
> Remember, AGC used to be called AVC Automatic Volume Control, 
> back in the 
> old days. If you choose a high threshold, THR, that means 
> that AVC does 
> almost nothing. AVC becomes MVW, manual volume control, 
> ....Meaning knobs 
> must be turned (AF).
> Steve Ellington
> N4LQ at carolina.rr.com
> ----- Original Message ----- 
> From: "Joe Planisky" <jplan at jeffnet.org>
> To: "W7TEA" <gtuck at mac.com>
> Cc: <elecraft at mailman.qth.net>
> Sent: Saturday, April 25, 2009 1:22 PM
> Subject: Re: [Elecraft] k3 NR Audio level increase
> 
> 
> > Good catch, Gary. AGC settings are the missing piece and 
> probably why 
> > some people aren't seeing this.  With an S9 signal, 
> NR=F4-4, BW=2.00, 
> > I get the following results for different settings of AGC 
> THR and AGC 
> > SLP when NR is engaged:
> >
> > THR=2, SLP= 0 +10.0 dB
> > THR=2, SLP= 5 + 2.7 dB
> > THR=2, SLP=10 - 6.0 dB
> > THR=2, SLP=15 -15.5 dB
> >
> > THR=4, SLP= 0 +15.2 dB
> > THR=4, SLP= 5 + 9.6 dB
> > THR=4, SLP=10 + 3.6 dB
> > THR=4, SLP=15 - 3.8 dB
> >
> > THR=6, SLP= 0 +16.6 dB
> > THR=6, SLP= 5 +13.3 dB
> > THR=6, SLP=10 + 7.9 dB
> > THR=6, SLP=15 + 1.5 dB
> >
> > THR=8, SLP= 0 +18.3 dB
> > THR=8, SLP= 5 +15.6 dB
> > THR=8, SLP=10 +11.7 dB
> > THR=8, SLP=15 + 7.0 db
> >
> > 73
> > --
> > Joe KB8AP
> >
> >
> > On Apr 25, 2009, at 8:21 AM, W7TEA wrote:
> >
> >>
> >> Joe, following your instructions, I cannot duplicate this 
> on my rig 
> >> listening to a S-9 signal.  I do find that if AGC-THR is 
> set below 5, 
> >> the audio drops significantly when initiating NR at my preferred 
> >> setting, 2-1.  Decreasing the AGC SLP increases the audio with NR 
> >> engaged.
> >>
> >> Gary W7TEA
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