Query for new DSP features

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Query for new DSP features

Elecraft mailing list
Wayne,
    I would like to see an improved Noise Reduction that doesn’t lower the volume or distort as much. Also the digital mode decode has never really worked well for me and, yes,
I read the manual about using it. Could you have the digital choices RTTY, PSK31, etc. instead of the current settings like FSK, data, etc?
Pie in the sky thought — Having the radio identify the type of digital signal being received with a word in the display and automatically change modes/settings to accommodate it.  73 Mike KF6KXG
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Re: Query for new DSP features

John Evans
And yet, I have no idea which Elecraft rig you are referring to here. 
Drives us K1, K2, KX3 owners crazy.

73 - john - n0hj

On 1/11/2019 9:49 PM, Walter Underwood wrote:

> It would be really great if the AF gain was automatically to keep the audio roughly level when NR is engaged. This drives me nuts, always riding the gain back and forth. I’m sure the gain adjustment would be different for different conditions, but at least get close.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
>> On Jan 11, 2019, at 8:38 PM, Mike Lichtman via Elecraft <[hidden email]> wrote:
>>
>> Wayne,
>>     I would like to see an improved Noise Reduction that doesn’t lower the volume or distort as much. Also the digital mode decode has never really worked well for me and, yes,
>> I read the manual about using it. Could you have the digital choices RTTY, PSK31, etc. instead of the current settings like FSK, data, etc?
>> Pie in the sky thought — Having the radio identify the type of digital signal being received with a word in the display and automatically change modes/settings to accommodate it.  73 Mike KF6KXG

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Re: Query for new DSP features

Bill Clarke
Regarding my K3 (original): DSP reduces the volume. When you turn the
volume up to where you can again hear - the junk noise level is right
back up there also.

A couple of days ago we had a major wind storm and a power line down the
road was periodically arcing. It was uncomfortable to listen to (on LSB
75 meters). I was using my Icom 7300 and pushed the NR button. Amazing,
the noises were reduced to nearly nothing and the audio level remained
as it had been. Then I switched to the K3 and tried the Noise Reduction
- no joy. I tried various settings, all under water and reduced volume.
I went back to the 7300 and continued enjoying my armchair copy 75 meter
QSO. Oh yes, I do know about reducing RX gain and proper use of ATT.

Sure, the argument can be made that the 7300 is a newer rig. You can
also argue that the DSP can be updated via software for the K3.

Sadly, since I purchased my IC-7300, I have only used the K3 for a few
CW contacts. Understand, my ham radio activities are 99% LSB on
160/75/40 meters. I do not DX or contest. No external VFO or keypad for
the 7300,which I do miss. However,a plastic stylus does wonderful on the
touch screen.


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Re: Query for new DSP features

Bob McGraw - K4TAX
In reply to this post by Elecraft mailing list
Use external audio processing, otherwise a compressor or limiter, with
variable attack and release and threshold and ratio controls.   Then
follow that with a small power amp to drive an external speaker.    
Frankly, I doubt you'd like the results.

I find it better to not use the NR feature due to the artifacts
introduced into the signal  and I find it much more satisfactory to
correctly adjust the Attenuation and RF Gain.

73

Bob, K4TAX


On 1/11/2019 10:49 PM, Walter Underwood wrote:

> It would be really great if the AF gain was automatically to keep the audio roughly level when NR is engaged. This drives me nuts, always riding the gain back and forth. I’m sure the gain adjustment would be different for different conditions, but at least get close.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
>> On Jan 11, 2019, at 8:38 PM, Mike Lichtman via Elecraft <[hidden email]> wrote:
>>
>> Wayne,
>>     I would like to see an improved Noise Reduction that doesn’t lower the volume or distort as much. Also the digital mode decode has never really worked well for me and, yes,
>> I read the manual about using it. Could you have the digital choices RTTY, PSK31, etc. instead of the current settings like FSK, data, etc?
>> Pie in the sky thought — Having the radio identify the type of digital signal being received with a word in the display and automatically change modes/settings to accommodate it.  73 Mike KF6KXG
>> ______________________________________________________________
>> Elecraft mailing list
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Re: Query for new DSP features

David Woolley (E.L)
In reply to this post by Elecraft mailing list
Do you have a reference for an algorithm that will do this?

Noise reduction is difficult because any effective noise reduction has
to recognize what is signal, and ideally what is the part of the signal
that matters to the human.  The hearing aid industry has been trying to
do this for years, with limited success.

I think the sort of noise reduction we are talking about here
essentially tries to decide which frequencies matter and which don't and
eliminate the latter.  However, it has to do this when what it is trying
to identify as signal is hidden by noise.

In practice, I think what these systems achieve is increased user
comfort, rather than recovering signal from noise, as humans are
probably still a lot better at extracting signal from noise than
algorithms, but they get tired in doing so.

One consequence of selective filtering will be a reduction in total
audio power.  I'd expect the total loudness to go down.  I guess you
could then renormalise, and increase the signal power to bring the total
power up to the same level.  However, most of are old enough to have a
lot of high frequency hearing loss, so one may find that correction
needed depends on specific hearing loss of the user and the original
spectrum of the noise; one needs to renormalise the power as waited by
the hearing sensitivity curve of the user.  I imagine you would need, at
least, a parameter to determine the degree of renormalisation.

Also, the more aggressive you make this sort of noise suppression, the
more likely it is to have false positives, and suppress important
frequencies.  Also, the more aggressive you make it, the more you will
get distortion as the result of modifying filter parameters on the fly.

Ultimately, though, the sort of noise that these systems are trying to
remove is random in nature, so you can never be completely sure what is
signal and what is noise.

(Hearing aids have a particularly difficult problem in that they are
dealing with cocktail party noise, where the noise is the summation of
lots of things that would, individually, be signals.)

(The ultimate noise reduction system would be one that recognized the
speech and regenerated it, complete with characteristics of the original
speaker.  However, doing that really well can only be done by looking
ahead several seconds, to be able to interpret meaning from what
follows, as well as what precedes.)

As a caution, I believe the K3 has two different noise handling
strategies:  the one I am talking about here, and one designed to deal
with impulse noise, where you simply cut out a short section of signal
around the noise pulse.

--
David Woolley
Owner K2 01623

On 12/01/2019 04:38, Mike Lichtman wrote:
> I would like to see an improved Noise Reduction that doesn’t lower the volume or distort as much.


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Re: Query for new DSP features

Don Wilhelm
David's analysis is correct.  Go to his last sentence - that is the
Noise Blanker (NB) and not Noise Reduction (NR).  NB punches a hole in
the signal in response to impulse noise.  It will cause signal
distortion, getting worse with more aggressive settings.

Noise Reduction (NR) depends on correlation techniques.  It has to
determine what is a signal, and then build a filter around that.
Once the filter is built, then the signal audio should be the same as
normal, but the noise content will be reduced.  Yes, NR will cause
distortion of the signal, but the idea is to be able to maintain
communications rather than simply to get rid of the noise.

The K3/K3S/KX3/KX2 NR has several settings to allow you to customize the
noise reduction to the particular noise you are encountering.  There is
no "one size fits all" for all noise sources.

I have "repaired" several K2s equipped with the KDSP2 which were sent to
me for "distorted audio" and the "cure" was to simply turn off NR in the
KDSP2.  Yes, you should expect some audio distortion when using NR.

73,
Don W3FPR

On 1/12/2019 11:51 AM, David Woolley wrote:

> Do you have a reference for an algorithm that will do this?
>
> Noise reduction is difficult because any effective noise reduction has
> to recognize what is signal, and ideally what is the part of the signal
> that matters to the human.  The hearing aid industry has been trying to
> do this for years, with limited success.
>
> I think the sort of noise reduction we are talking about here
> essentially tries to decide which frequencies matter and which don't and
> eliminate the latter.  However, it has to do this when what it is trying
> to identify as signal is hidden by noise.
>
> In practice, I think what these systems achieve is increased user
> comfort, rather than recovering signal from noise, as humans are
> probably still a lot better at extracting signal from noise than
> algorithms, but they get tired in doing so.
>
> One consequence of selective filtering will be a reduction in total
> audio power.  I'd expect the total loudness to go down.  I guess you
> could then renormalise, and increase the signal power to bring the total
> power up to the same level.  However, most of are old enough to have a
> lot of high frequency hearing loss, so one may find that correction
> needed depends on specific hearing loss of the user and the original
> spectrum of the noise; one needs to renormalise the power as waited by
> the hearing sensitivity curve of the user.  I imagine you would need, at
> least, a parameter to determine the degree of renormalisation.
>
> Also, the more aggressive you make this sort of noise suppression, the
> more likely it is to have false positives, and suppress important
> frequencies.  Also, the more aggressive you make it, the more you will
> get distortion as the result of modifying filter parameters on the fly.
>
> Ultimately, though, the sort of noise that these systems are trying to
> remove is random in nature, so you can never be completely sure what is
> signal and what is noise.
>
> (Hearing aids have a particularly difficult problem in that they are
> dealing with cocktail party noise, where the noise is the summation of
> lots of things that would, individually, be signals.)
>
> (The ultimate noise reduction system would be one that recognized the
> speech and regenerated it, complete with characteristics of the original
> speaker.  However, doing that really well can only be done by looking
> ahead several seconds, to be able to interpret meaning from what
> follows, as well as what precedes.)
>
> As a caution, I believe the K3 has two different noise handling
> strategies:  the one I am talking about here, and one designed to deal
> with impulse noise, where you simply cut out a short section of signal
> around the noise pulse.
>
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Re: Query for new DSP features

K7TV
In reply to this post by John Evans
The noise level at my QTH is not nearly as bad as many of you have. The K3 S-meter tends to read around S4 on the background noise noise (SSB bandwidth, 20m preamp off, atten off). When it comes to engaging NR, like many others I have in the past tended to crank up the aggressiveness etc and noted a loss of apparent volume on the wanted signal, and apparent loss of the higher frequency voice components. I have compensated by cranking up the volume and widening the passband (which helped little as the received station had insufficient boost of highs). I have admired the apparently better results from other DSP implementations such as BHI and other radios. Lately I have modified my approach to using the K3 DSP, and found much better results. For ssb I now have NR engaged full time and like it. The setting is the least aggressive possible: F1-1. I used to have the impression that this setting did little to help, but I have changed my opinion. The sound with this weak NR on now seems very normal and comfortably intelligible. If I turn NR off, I can still read the signal, but it sounds harsh and tiring. I can't say the NR makes an unreadable signal readable, but it makes the copy more comfortable. My old brain seems to, slowly, adjust its own filtering to fit what is being heard, not just to focus on the wanted cw signal in a wider passband, but also when listening to voice when switching between NR on/off. This may be just my speculation, but subjectively, even with no radio involved, I seem to need an adjustment period also when listening to different adult voices, and especially when going between an adult voice and that of a small child. The existing K3 DSP seems to be optimized based on objectively measurable criteria that are somewhat at odds with the strange workings of the human auditory system. Perhaps the addition of a tone control that alters the low/high tonal balance would be a helpful new resource for those who feel the NR makes signals sound weak or too bassy. The tone control setting could be automatically engaged with an emphasis on the highs when NR is engaged. It could also be helpful as a manual control for adapting to stations that have not adjusted their transmit equalizer to fit the operator's voice. Besides a low/high tilt, a peak/notch function might be helpful.
73,
Erik K7TV

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Walter Underwood
Sent: Saturday, January 12, 2019 9:21 AM
To: Elecraft Reflector Reflector <[hidden email]>
Subject: Re: [Elecraft] Query for new DSP features

Sorry, KX3. Though I think the K3 and KX2 use similar algorithms.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Jan 11, 2019, at 8:53 PM, John Evans <[hidden email]> wrote:
>
> And yet, I have no idea which Elecraft rig you are referring to here.  Drives us K1, K2, KX3 owners crazy.
>
> 73 - john - n0hj
>
> On 1/11/2019 9:49 PM, Walter Underwood wrote:
>> It would be really great if the AF gain was automatically to keep the audio roughly level when NR is engaged. This drives me nuts, always riding the gain back and forth. I’m sure the gain adjustment would be different for different conditions, but at least get close.
>>
>> wunder
>> K6WRU
>> Walter Underwood
>> CM87wj
>> http://observer.wunderwood.org/ (my blog)
>>
>>> On Jan 11, 2019, at 8:38 PM, Mike Lichtman via Elecraft <[hidden email]> wrote:
>>>
>>> Wayne,
>>>    I would like to see an improved Noise Reduction that doesn’t
>>> lower the volume or distort as much. Also the digital mode decode has never really worked well for me and, yes, I read the manual about using it. Could you have the digital choices RTTY, PSK31, etc. instead of the current settings like FSK, data, etc?
>>> Pie in the sky thought — Having the radio identify the type of
>>> digital signal being received with a word in the display and
>>> automatically change modes/settings to accommodate it.  73 Mike
>>> KF6KXG
>
> ______________________________________________________________
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> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]

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Re: Query for new DSP features

Bill Steffey NY9H

forty years in the audio business have allowed me to hear some of the
best and worst audio/\
I bought clear speech before and after Bob tired selling it, and two
others before finding the BHI product series from England. Some how
their algorithm, to me at least, does the least harm to human voice when
engaging the NR function. With both a 7800 and K3 I ended up with their
dual channel NR with EQ. I did not want or need the EQ, but wanted the
two channels for the dual receiver sets. I use a large Microham to
switch the audio around feeding the BHIs. Graham at BHI explained their
algorithm to me at Dayton, and sounded somewhat patent protected.
I had expected, when the K3 upgrades came along with the additional set
of settings for the NR I could delete the BHI. did not happen. Amazing
how a pile of 1s & 0s can make such a difference.And I somehow it passes CW.
picky picky picky... I know .

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Re: Query for new DSP features

Christopher Hoover
In reply to this post by Elecraft mailing list
On Fri, Jan 11, 2019 at 8:50 PM Walter Underwood <[hidden email]>
wrote:

> It would be really great if the AF gain was automatically to keep the
> audio roughly level when NR is engaged. This drives me nuts, always riding
> the gain back and forth. I’m sure the gain adjustment would be different
> for different conditions, but at least get close.
>

+1 to this
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Re: Query for new DSP features

hbjr
I have used an outboard compressor/expander for this (paired with a 7 band parametric(quasi) equalizer) and besides normalizing audio levels can squash static crashes and pad certain frequencies above a certain intensity automatically (similar to de-easing in function).  It was more analog than digital but worked really well - it was an older Aphex with a noise gate and outboard eq. Not easy to setup though. Required an audio amplifier or powered speaker downstream.

Hank
K4HYJ

> On Jan 12, 2019, at 10:48 PM, Christopher Hoover <[hidden email]> wrote:
>
> On Fri, Jan 11, 2019 at 8:50 PM Walter Underwood <[hidden email]>
> wrote:
>
>> It would be really great if the AF gain was automatically to keep the
>> audio roughly level when NR is engaged. This drives me nuts, always riding
>> the gain back and forth. I’m sure the gain adjustment would be different
>> for different conditions, but at least get close.
>>
>
> +1 to this
> ______________________________________________________________
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Re: Query for new DSP features

Roger D Johnson
In reply to this post by Bill Clarke
What ever happened to giving us some alternate selectivity on the APF?

73, Roger


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Re: Query for new DSP features

Bill Steffey NY9H
In reply to this post by hbjr
sounds like  an Aphex Compellor



On 1/13/2019 10:01 AM, HB wrote:

> I have used an outboard compressor/expander for this (paired with a 7 band parametric(quasi) equalizer) and besides normalizing audio levels can squash static crashes and pad certain frequencies above a certain intensity automatically (similar to de-easing in function).  It was more analog than digital but worked really well - it was an older Aphex with a noise gate and outboard eq. Not easy to setup though. Required an audio amplifier or powered speaker downstream.
>
> Hank
> K4HYJ
>
>> On Jan 12, 2019, at 10:48 PM, Christopher Hoover <[hidden email]> wrote:
>>
>> On Fri, Jan 11, 2019 at 8:50 PM Walter Underwood <[hidden email]>
>> wrote:
>>
>>> It would be really great if the AF gain was automatically to keep the
>>> audio roughly level when NR is engaged. This drives me nuts, always riding
>>> the gain back and forth. I’m sure the gain adjustment would be different
>>> for different conditions, but at least get close.
>>>
>>
>> +1 to this
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
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>
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Re: Query for new DSP features

iw2noy
In reply to this post by Elecraft mailing list
Hello all, Hello Wayne,

following Mike KF6KXG suggestion, i would like to have a more intuitive
Noise Reduction (NR).
I used several last Icom or Yaesu model and their NR are more intuitive
and easy to use, without loose efficiency and without ruin the signal
audio and strenght.
Especially the Yaesu, in models like the Ftdx3000, Ftdx5000, FT-991:
where you simply push the DNR button and everything goes away except the
signal that you can easily hear in the silence.

I love my K3s for many aspects and i will never change it for another
radio but, the NR function always disappointed me.
Maybe is my problem but there are too much settings and often doesn't
work as aspected, also it need to change settings when condition change
and is difficult find one setting for all.

I would like to have and NR with just the level of intervention and that
work like the last Yaesu, where the noise goes away and signal remain in
the silence, also without changing the strenght of the signal and
without causing distortions on the audio.

I had a FTdx3000 before the K3s and the only thing i am really missing
is the Yaesu DNR, all the rest is done also by the K3s and better than
the 3000.

I hope could be interesting and that can help and... happen :-)

Thanks a lot, Graziano Roccon IW2NOY

PS
Why not... a more intuitive digital mode name in the menu are welcome
:-)


l 2019-01-12 05:38 Mike Lichtman via Elecraft ha scritto:

> Wayne,
>     I would like to see an improved Noise Reduction that doesn’t lower
> the volume or distort as much. Also the digital mode decode has never
> really worked well for me and, yes,
> I read the manual about using it. Could you have the digital choices
> RTTY, PSK31, etc. instead of the current settings like FSK, data, etc?
> Pie in the sky thought — Having the radio identify the type of digital
> signal being received with a word in the display and automatically
> change modes/settings to accommodate it.  73 Mike KF6KXG
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Re: Query for new DSP features

Wes Stewart-2
In reply to this post by David Woolley (E.L)
https://www.youtube.com/watch?v=FrVDL_-HOds starting at 41 minutes. 
Particularly at 1 hour 3 minutes.

On 1/12/2019 9:51 AM, David Woolley wrote:
> Do you have a reference for an algorithm that will do this?
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Re: Query for new DSP features

David Woolley (E.L)
The part at 1:03:00 involves a signal that had a large impulsive
component, and was treated with a combination of noise blanking and
noise reduction.  Applying pure noise reduction wasn't going to help.
You can actually see from the pure noise reduction example they played,
that they were not comfortable with trying to do pure noise reduction on
a signal that wasn't easily copyable without it.

More importantly, nowhere from the 46 minutes mark do they describe
their algorithms, although, as open source code, it will be possible to
find them.

I would assume that the K3 uses LMS.  The spectral one needs similar but
greater processing to that needed in the phase shifting proposal.  It
needs greater, in that the it has to compute the parameters by which to
multiply the FFT bins on the fly, whereas the phase shifting case only
needs to compute them when you turn the control knob.  Consequently it
is subject to the same performance question:  does the K3 hardware
actually have enough processing power to run the algorithm.  (I assume
LMS is used because the processing power requirements are rather less.)

I don't know whether it has the power needed.

My description of the general problem of noise reduction actually more
accurately fits the spectral processing model. I believe LMS is trying
to achieve a similar effect, but in a more computationally efficient manner.

Pure morse code doesn't actually need complex noise reduction, as simply
using a narrow filter will do the same thing as a good spectral noise
reduction algorithm would attempt to achieve.  It can, though, benefit
from noise blanking.  I say morse code, because a literally CW signal
can get perfect (Gaussian) noise reduction by using an infinitesimally
narrow filter.  Actually, for a fair test, they should have also shown
the result of applying a very narrow filter to the power-line noise example.

Nothing in the part of the talk I listened to addressed the problem of
distortion caused by the suppression algorithm, in particular the
non-linearities caused by modifying the parameters on the fly.


On 15/01/2019 02:53, Wes Stewart wrote:
> https://www.youtube.com/watch?v=FrVDL_-HOds starting at 41 minutes.
> Particularly at 1 hour 3 minutes.
>
> On 1/12/2019 9:51 AM, David Woolley wrote:
>> Do you have a reference for an algorithm that will do this?
>

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