K3 NR triggering

[Steve Ellington]

I just had a CW QSO on a noisy 80m. Here's what I noticed with NR set for
F1-3. BW set for 2.5 kHz.
QRN very loud! I pushed NR. Band goes almost totally silent. Calling CQ with
the bug was like being in TX mode but I was using QSK as always. Wow...Nice
and quiet. Then someone answered my CQ. On his very first DIT, the noise
level jumped up and stayed up throughout the entire QSO. It was quieter than
no NR at all but why should it stay that way???
I've been playing with it and sure enough, I can turn NR off then back on
and the noise vanishes. Tune across a CW signal and it triggers the noise to
return.
Steve
N4LQ
[hidden email]

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[Bill W4ZV]

Steve Ellington wrote

I just had a CW QSO on a noisy 80m. Here's what I noticed with NR set for
F1-3. BW set for 2.5 kHz.
QRN very loud! I pushed NR. Band goes almost totally silent. Calling CQ with
the bug was like being in TX mode but I was using QSK as always. Wow...Nice
and quiet. Then someone answered my CQ. On his very first DIT, the noise
level jumped up and stayed up throughout the entire QSO. It was quieter than
no NR at all but why should it stay that way???

Remember that NR is an adaptive filter.  When you perturb it with a coherent signal it rebuilds the filter around that signal.  F1 is the longest tap setting which means it has the greatest stored data stream and will take the longest to respond when you add new data (i.e. a signal).  Once the new input to the filter (signal plus noise) is steady state, the filter will then stay in that state until the inputs change again (i.e. when the signal goes away).

73,  Bill

[Steve Ellington]

Thanks for the nice explanation Bill. It is effective but weird. Somone
needs to make a movie.
Steve
N4LQ
[hidden email]
----- Original Message -----
From: "Bill W4ZV" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, August 27, 2009 7:12 AM
Subject: Re: [Elecraft] [K3] K3 NR triggering

>
>
>
> Steve Ellington wrote:
>>
>> I just had a CW QSO on a noisy 80m. Here's what I noticed with NR set for
>> F1-3. BW set for 2.5 kHz.
>> QRN very loud! I pushed NR. Band goes almost totally silent. Calling CQ
>> with
>> the bug was like being in TX mode but I was using QSK as always.
>> Wow...Nice
>> and quiet. Then someone answered my CQ. On his very first DIT, the noise
>> level jumped up and stayed up throughout the entire QSO. It was quieter
>> than
>> no NR at all but why should it stay that way???
>>
>
> Remember that NR is an adaptive filter.  When you perturb it with a
> coherent
> signal it rebuilds the filter around that signal.  F1 is the longest tap
> setting which means it has the greatest stored data stream and will take
> the
> longest to respond when you add new data (i.e. a signal).  Once the new
> input to the filter (signal plus noise) is steady state, the filter will
> then stay in that state until the inputs change again (i.e. when the
> signal
> goes away).
>
> 73,  Bill
> --
> View this message in context:
> http://n2.nabble.com/K3-NR-triggering-tp3521099p3524344.html
> Sent from the [K3] mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
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>
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> Please help support this email list: http://www.qsl.net/donate.html 

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Please help support this email list: http://www.qsl.net/donate.html