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K3 Noise Reduction question

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k6dgw

K3 Noise Reduction question

I operate mainly CW and while the NB is very effective for me on CW,
I've never seen much advantage to the NR at narrow CW bandwidths. I had
occasion to be on SSB this week attempting to work several SOTA summit
activations, and tried the NR. At the wider SSB BW, it made a great
difference.

With NR however, even at F1-1 [which I think means least aggressive],
while the nasty line noise really fell, the SSB signal acquired a
profound echo which made it very hard to understand. I'm running FW4.39
and whatever DSP came with it. Is this reverberation [it's more like
that than a distinct echo, like talking through a long pipe] normal?
The further "up" the NR scale I went, the more pronounced it got, and
beyond F1-4, the signal was indecipherable.

Full Disclosure: My hearing sucks and has since one night in 1965 on
the other side of the planet, so me telling you what something sounds
like can be somewhat of a joke. I can't use my hearing aids under my
headphones, so I run the AF gain high ["afterburner roar" or close], but
the reverb effect definitely is controlled by the NR.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

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ab2tc

Re: K3 Noise Reduction question

Hi,

Have you tried the NB (*not* NR)? I find it very effective against power line noise. I use the setting t2-6, IF off. For a long time I was using a combination of DSP and IF setting, but found that the IF contribution was little or non-existing, so I switched to DSP NB only.

AB2TC - Knut

k6dgw wrote

I operate mainly CW and while the NB is very effective for me on CW,
I've never seen much advantage to the NR at narrow CW bandwidths. I had
occasion to be on SSB this week attempting to work several SOTA summit
activations, and tried the NR. At the wider SSB BW, it made a great
difference.

With NR however, even at F1-1 [which I think means least aggressive],
while the nasty line noise really fell, the SSB signal acquired a
profound echo which made it very hard to understand. I'm running FW4.39
and whatever DSP came with it. Is this reverberation [it's more like
that than a distinct echo, like talking through a long pipe] normal?
The further "up" the NR scale I went, the more pronounced it got, and
beyond F1-4, the signal was indecipherable.

Full Disclosure: My hearing sucks and has since one night in 1965 on
the other side of the planet, so me telling you what something sounds
like can be somewhat of a joke. I can't use my hearing aids under my
headphones, so I run the AF gain high ["afterburner roar" or close], but
the reverb effect definitely is controlled by the NR.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

<snip>

ab2tc

Re: K3 Noise Reduction question

In reply to this post by k6dgw

k6dgw wrote

I operate mainly CW and while the NB is very effective for me on CW,
I've never seen much advantage to the NR at narrow CW bandwidths. I had
occasion to be on SSB this week attempting to work several SOTA summit
activations, and tried the NR. At the wider SSB BW, it made a great
difference.

With NR however, even at F1-1 [which I think means least aggressive],
while the nasty line noise really fell, the SSB signal acquired a
profound echo which made it very hard to understand. I'm running FW4.39
and whatever DSP came with it. Is this reverberation [it's more like
that than a distinct echo, like talking through a long pipe] normal?
The further "up" the NR scale I went, the more pronounced it got, and
beyond F1-4, the signal was indecipherable.

Full Disclosure: My hearing sucks and has since one night in 1965 on
the other side of the planet, so me telling you what something sounds
like can be somewhat of a joke. I can't use my hearing aids under my
headphones, so I run the AF gain high ["afterburner roar" or close], but
the reverb effect definitely is controlled by the NR.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

<snip>

k6dgw

Re: K3 Noise Reduction question

In reply to this post by ab2tc

On 4/27/2012 2:32 PM, ab2tc wrote:
> Hi,
>
> Have you tried the NB (*not* NR)? I find it very effective against power
> line noise. I use the setting t2-6, IF off. For a long time I was using a
> combination of DSP and IF setting, but found that the IF contribution was
> little or non-existing, so I switched to DSP NB only.

Yeppers, my K3 is S/N 642 [it tells me every time I power up just in
case I forget :-)] and I have used NB consistently on both CW and SSB.
IF NB often drops the level 2 S-Units or sometimes 3. Both IF and DSP
seem to be quite sensitive to the character of the noise, I run the DSP
between T1-5 and T2-3 usually, IF is usually on NAR 3 or 4.

On CW, I've never found much benefit from NR, regardless of the
"aggression setting," which I've always attributed to a 150-250 Hz BW.
When running in a contest, I'll usually run the BW at 450-500 so I can
spot off-freq callers and the NR seems to have slightly more effect at
the wider BW. Since I got the P3 however, I can *see* the off-freq
callers however and just go to them with RIT.

I don't think I've ever really tried NR on SSB until this week, when I
noticed the reverb effect. NB is equally effective on SSB as on CW, the
setting is usually a bit different though at the wider BW.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

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Don Wilhelm-4

Re: K3 Noise Reduction question

In reply to this post by k6dgw

Fred,

Perhaps an explanation of how NR works will help you understand what you
are hearing a bit better. The NR algorithm looks for some sequence that
it can define as a signal, and then builds a filter around it. The type
of filter is determined by the parameters you have set.

That is why you have found there is no need for NR when using CW with
narrow filters. On SSB, yes, some settings can sound "pretty ratty".
Enough so that I do not use it on SSB. But do give some of the settings
above 4-4 a try - those use a different algorithm and may be worthwhile
when needed.

73,
Don W3FPR

On 4/27/2012 4:58 PM, Fred Jensen wrote:

> I operate mainly CW and while the NB is very effective for me on CW,
> I've never seen much advantage to the NR at narrow CW bandwidths. I had
> occasion to be on SSB this week attempting to work several SOTA summit
> activations, and tried the NR. At the wider SSB BW, it made a great
> difference.
>
> With NR however, even at F1-1 [which I think means least aggressive],
> while the nasty line noise really fell, the SSB signal acquired a
> profound echo which made it very hard to understand. I'm running FW4.39
> and whatever DSP came with it. Is this reverberation [it's more like
> that than a distinct echo, like talking through a long pipe] normal?
> The further "up" the NR scale I went, the more pronounced it got, and
> beyond F1-4, the signal was indecipherable.
>
> Full Disclosure: My hearing sucks and has since one night in 1965 on
> the other side of the planet, so me telling you what something sounds
> like can be somewhat of a joke. I can't use my hearing aids under my
> headphones, so I run the AF gain high ["afterburner roar" or close], but
> the reverb effect definitely is controlled by the NR.
>
> 73,
>

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Arthur Burke

Re: K3 Noise Reduction question

In reply to this post by k6dgw

I have some tinnitus (sp?) so, when things are really, really quiet, I hear
things
that really aren't there! Aside from that, a recent hearing test indicated
my hearing
was normal for my age (67) and I hear equally well (or equally poor!) with
both ears.

My experience with the NR has been somewhat the opposite of yours. I love
to back the
RF gain down just a tad, turn on the NR (don't remember the exact setting
right off the top
of my head) to where I have to strain to hear band noise. Then, when a
signal does appear, it sort of magically jumps out of the speakers!

Art - N4PJ

On Fri, Apr 27, 2012 at 4:58 PM, Fred Jensen <[hidden email]> wrote:

RobertG

Re: K3 Noise Reduction question

In reply to this post by k6dgw

I also note the "hollow" sound to SSB when using the K3 NR. If I use it
at all, it's at the lowest setting, 1-1. I had the same listening
experience with the K2 DSP NR unit. It worked well on CW - sometimes
miraculous - but for my ears, useless on SSB. The K3 NB works on all
modes, every time. I haven't tried the higher K3 NR setting for SSB,
being primarily a CW op. Also, my hearing is poor. Hearing aids all the
time except when under the head phones and operating CW.
...robert

On 4/27/2012 20:58, Fred Jensen wrote:

--
Robert G. Strickland, PhD, ABPH - KE2WY
[hidden email]
Syracuse, New York, USA
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Guy, K2AV

Re: K3 Noise Reduction question

In reply to this post by k6dgw

Hi Fred,

>From where I sit, if the NR display has a little "m" between NR and F,
those are methods best on voice (F5-1 through F8-4), while without the
little "m" (F1-1 through F4-4) are methods better with CW. That is not an
absolute rule of course and many people have preferences which don't abide
by those categories. People differ wildly on their sound perceptions and
preferences. Some people can't stand a hollow sound, like scraping a
chalkboard with fingernails. Others need clear highs in speech or they
just cannot understand it.

It is not even a tiny bit surprising you find 1-1 "hollow" on SSB. 1-1 is
a method designed to dynamically peak up a frequency, DEFINITELY NOT a band
of frequencies like SSB. If you turn on 160m and listen to the static
crashes using 1-1, you can hear the method try to tune in on a center, and
this will move around just depending on the nature of the static crash. If
that hones in on a low frequency on voice, then I LOSE the all important
highs for sibilant sounds, this does not happen on 6-2 which is one of my
favorites.

Personally, I do NOT agree with the Noise Reduction section in the current
K3 manual on page 25, where they only recommend 1-1 through 4-1. There is
not even one NON-mixed setting that I like on SSB.

Nothing wrong, your K3 is not busted, YOU are not busted. If you like it,
use it, if you don't like it, don't use it. Try them all on for size.

73, Guy.

On Fri, Apr 27, 2012 at 4:58 PM, Fred Jensen <[hidden email]> wrote: