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What should I be hearing when I use the K3 Noise Filter?

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Robin Diane Goldstein

What should I be hearing when I use the K3 Noise Filter?

hi all... elecraft/k3 newbie here (new owner of gently-cared-for
#2102)... have read everything i can find, but can't dig up an
answer, so this is my first post to the list:

i've downloaded the latest beta firmware and have read all the posts
reciting joy and jubilation (my words) in connection with the
operation of the Noise Filter... but i think i'm missing something...
i work almost exclusively SSB and find that i'm listening to stations
buried in the QRN... i -thought- this was where the Noise Filter was
suppose to help, but when i turn on the NF and adjust it from 1-1 to
4-4 i seem to hear a somewhat filtered/somewhat distorted version of
the input signal. i understand that the filter works automagically,
but as i go from X-1 to X-4 it sounds like some kind of notch filter
is being applied in increasing amounts, but not in a
meaningful/useful way... then it goes from X-4 to Y-1 and the
narrowing 'hiss' starts all over again, this time with a slightly
harmonic distortion.

on very strong signals i can sometimes find a setting (usually 3-2 or
3-3) that sharpens up the audio just a bit, but those signals usually
are loud enough to blast through the noise anyway... what i'm looking
for is help with the S2-S3 stuff.

any advice or perhaps a pointer to an audio/video file showing the
filter in (proper) operation?

btw, the NB seems to work just fine as does the notch filter.

many thanks and 73!
robin (K9RDG)
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ab2tc

Re: What should I be hearing when I use the K3 Noise Filter?

Hi,

I believe you are referring to the Noise Reduction "NR" filter. I am afraid that you have discovered that if this emperor has any clothes at all, they are pretty skimpy. I have never seen a proper problem statement as to what type of noise this filter is supposed to remove or reduce. Atmospheric noise is pretty close to white gaussian random noise which cannot be removed by any means. The effect of the NR filter is largely to provide a more pleasing psycho-acoustic experience (maybe). This would explain the widely different experiences people are having with this filter. My wish is for Elecraft to stop using limited resources on this function. There are still serious problems with maintaining power control on SSB. I am still experiencing and seeing reports on the reflector that after certain actions (band change, power change) power output is low and will only very slowly grow to the demanded level unless you perform some other action such as transmitting a single CW dit or a short squirt of RTTY power (which is what I do). This is a real problem requring a solution.

AB2TC - Knut

Robin Diane Goldstein wrote

hi all... elecraft/k3 newbie here (new owner of gently-cared-for
#2102)... have read everything i can find, but can't dig up an
answer, so this is my first post to the list:

i've downloaded the latest beta firmware and have read all the posts
reciting joy and jubilation (my words) in connection with the
operation of the Noise Filter... but i think i'm missing something...
i work almost exclusively SSB and find that i'm listening to stations
buried in the QRN... i -thought- this was where the Noise Filter was
suppose to help, but when i turn on the NF and adjust it from 1-1 to
4-4 i seem to hear a somewhat filtered/somewhat distorted version of
the input signal.

<snip>

ka9zap

Re: What should I be hearing when I use the K3 Noise Filter?

In reply to this post by Robin Diane Goldstein

Hi Robin
The last firmware NR was a bit on the to aggressive side making
everything sound like it was
coming through a pipe or hollow sounding I found my self not using it
often to fatiguing over
time to listen to.
This revised NR is a bit on the other side of the spectrum while the
finish product is not
hollow sounding it does not offer a lot of reduction.

Could be the code writers are "range finding" shooting long then short
to zero in nirvana
as a cw first operator who is not afraid to go very narrow on the
filters I do not find myself
using the NR a lot the suttle influence is closer to my liking then the
to agressive aproach.
So might it be nice to have both in the next release the 1-4 2-4 could
be like but with a bit
of tweaking for more Reduction of Noise but not to much and then the 3-4
4-4 come back in
from the other side of to much NR where it was hollow through a pipe
response

Robin Diane Goldstein wrote:

> hi all... elecraft/k3 newbie here (new owner of gently-cared-for
> #2102)... have read everything i can find, but can't dig up an
> answer, so this is my first post to the list:
>
> i've downloaded the latest beta firmware and have read all the posts
> reciting joy and jubilation (my words) in connection with the
> operation of the Noise Filter... but i think i'm missing something...
> i work almost exclusively SSB and find that i'm listening to stations
> buried in the QRN... i -thought- this was where the Noise Filter was
> suppose to help, but when i turn on the NF and adjust it from 1-1 to
> 4-4 i seem to hear a somewhat filtered/somewhat distorted version of
> the input signal. i understand that the filter works automagically,
> but as i go from X-1 to X-4 it sounds like some kind of notch filter
> is being applied in increasing amounts, but not in a
> meaningful/useful way... then it goes from X-4 to Y-1 and the
> narrowing 'hiss' starts all over again, this time with a slightly
> harmonic distortion.
>
> on very strong signals i can sometimes find a setting (usually 3-2 or
> 3-3) that sharpens up the audio just a bit, but those signals usually
> are loud enough to blast through the noise anyway... what i'm looking
> for is help with the S2-S3 stuff.
>
> any advice or perhaps a pointer to an audio/video file showing the
> filter in (proper) operation?
>
> btw, the NB seems to work just fine as does the notch filter.
>
> many thanks and 73!
> robin (K9RDG)
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

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Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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ab2tc

Re: What should I be hearing when I use the K3 Noise Filter?

In reply to this post by ab2tc

PS.

The noise blanker (NB) on the other hand is fabulous on impulse noise. I sometimes have very serious power line noise and most of the time the NB totally obliterates it. In all cases it seriously reduces it.

AB2TC - Knut

ab2tc wrote

Hi,

I believe you are referring to the Noise Reduction "NR" filter.<snip>

ka9zap

Re: What should I be hearing when I use the K3 Noise Filter?

In reply to this post by Robin Diane Goldstein

Hi Robin
Firmware 3.25
S/N 3142
Born on Date 6/13/09

The last firmware NR was a bit on the to aggressive side making
everything sound like it was coming through a pipe or hollow
sounding. I found my self not using it often to fatiguing over
time to listen to, especially on SSB.
This revised NR is a bit on the other side of the spectrum while the
finish product is not hollow sounding or through a pipe sounding
it does not offer a lot of reduction. I tried dual dsp years ago
on my ft1000d using two dsp units in stereo to really kill the band
noise it works ok the JPS NIR 12 uses this approach I believe.
This could also be done with a out board unit in a speaker I put
the board from a AM Com ClearSpeech dsp in my Yaesu station speaker
I like it a lot but have not tried that speaker yet on the K3 yet.

I almost want to say there has been a tweak of the audio response
also sounding a bit more full less intense with a hiss on the high
end, which I pulled down using the RX EQ, am I imagining this or is
this a real tweak?
I like the SSB audio response (with no DSP NR influence) better now.

I really need to have two K3's side by side to test or A/B the
firmware release to be absolutely sure, I do keep notes on the first
impression after an up date, better sounding is noted.

Could be the code writers are "range finding" shooting long then
short to zero in nirvana?
As a cw first operator who is not afraid to go very narrow on the
filters I did not find myself using the NR a lot the subtle influence
is closer to my liking then the to aggressive approach.
The Hi Q ringing of the audio filters of the past is something I never
liked or could operate using.
My ft1000d with a 500 pitch tweak the radio narrow shift /width narrow
250 Collins filter get it the best that can be then toss in the APF
which did not add ringing was all good, it just made the signal louder.

So might it be nice to have both in the next release the 1-4 2-4 could
be like but with a bit of tweaking for more Reduction of Noise but not
to much and then the 3-4 4-4 come back in from the other side of to
much NR where it was hollow through a pipe response.

Coming in from both sides a bit at a time might satisfy every one.

Sorry for the first post I hit send before spell check and completing
my thoughts on this matter.

Regards
Art
ka9zap
PS Hopping for a Audio Peak Filter APF like my ft1000d has.

Robin Diane Goldstein wrote: