Re: [wsjt-devel] Cannot clone Hamlib fork

[Daniel Uppström via wsjt-devel]

Ok I see.
Then someone better update the info in the INSTALL file 
(https://sourceforge.net/p/wsjt/wsjtx/ci/master/tree/INSTALL):


The Hamlib library is required. Currently WSJT-X needs to be built using 
a forked version of the Hamlib git master. This fork contains patches 
not yet accepted by the Hamlib development team which are essential for 
correct operation of WSJT-X. To build the Hamlib fork from sources 
something like the following recipe should suffice: $ mkdir 
~/hamlib-prefix $ cd ~/hamlib-prefix $ git clone 
git://git.code.sf.net/u/bsomervi/hamlib src

Thanks!




On 12/10/23 21:48, Black Michael wrote:

No...that particular fork was created when Hamlib was not getting updated.

Mike W9MDB








On Sunday, December 10, 2023 at 02:27:28 PM CST, Daniel 
Uppström  wrote:





Oh, that's unfortunate.
I thought this particular fork was necessary for WSJT-X and not the main branch 
of Hamlib?

/SM6VFZ

Den sön 10 dec. 2023 19:22Black Michael via 
wsjt-devel  skrev:

Since Bill is silent key that repository has been removed.

The permanent home of Hamlib is here:

https://github.com/Hamlib/Hamlib

Mike W9MDB






On Saturday, December 9, 2023 at 02:33:42 PM CST, Daniel Uppström via 
wsjt-devel  wrote:





Hi,
When trying to build WSJT-X from source these days I cannot any longer access 
the Hamlib fork:

git clone git://git.code.sf.net/u/bsomervi/hamlib src
Cloning into 'src'...
fatal: remote error: access denied or repository not exported: 
/u/bsomervi/hamlib

Any ideas?

/Daniel SM6VFZ

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Re: [wsjt-devel] WSJT noise estimates

[Joe Fleagle via wsjt-devel]

Thanks for the explanation Joe.  I had not seen that before. Signals do not 
affect the noise estimate which was one of the answers I was looking for.

Joe

> On Dec 10, 2023, at 11:21, Joe Taylor via wsjt-devel 
>  wrote:
> 
> Hi Joe,
> 
>> On 12/9/2023 9:56 PM, w0fy--- via wsjt-devel wrote:
>> Been wondering how WSJT-X generates the noise power estimate it uses to 
>> calculate SNR for each FT8 signal.  Does it simply collect all the signals 
>> and noise over the bandwidth selected on the waterfall and call that the 
>> noise power level or does it take a quick snapshot of  the background noise 
>> level during the brief quiet period at the end of each 15 second FT8 
>> sequence? Or is it more complicated than that?
> 
> This question has been asked and answered many times on this and similar 
> forums.  WSJT-X measures noise power by computing the spectrum of the 
> receiver's output, averaged over the reception interval, and fitting a 
> baseline to the regions that have no discernible signal present.  The 
> resulting value -- effectively a noise power density, or power per unit 
> bandwidth -- is then scaled to yield noise power in 2500 Hz bandwidth.
> 
>> I am plagued with a S2 -S3 noise level on 6 meters nearly all the time that 
>> if not AWGN is pretty close to it.  10 meters is even worse. The DSP noise 
>> blanker in my TS590 will reduce it slightly. I estimate this is degrading my 
>> ability to decode FT8 signals on 6 by nearly 20 dB compared to the noise 
>> level generated by a 50 ohm resistor.  I don’t use an LNA ahead of the radio 
>> – would be pointless.  I don’t use the noise reduction feature in the radio 
>> either as it tends to lose very weak signals completely.
> 
> It's OK to use your receiver's noise blanker to remove impulsive noise.
> 
> Do NOT use "noise reduction" features, and do NOT use a receiver bandwidth 
> narrower than about 2.5 kHz.  Wider bandwidths are even better, up to 4 or 5 
> kHz.  WSJT-X does all necessary narrow-band filtering in software.
> 
>-- 73, Joe, K1JT
> 
> 
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Re: [wsjt-devel] Cannot clone Hamlib fork

[Black Michael via wsjt-devel]

No...that particular fork was created when Hamlib was not getting updated.

Mike W9MDB








On Sunday, December 10, 2023 at 02:27:28 PM CST, Daniel Uppström 
 wrote: 





Oh, that's unfortunate.
I thought this particular fork was necessary for WSJT-X and not the main branch 
of Hamlib?

/SM6VFZ

Den sön 10 dec. 2023 19:22Black Michael via wsjt-devel 
 skrev:
> Since Bill is silent key that repository has been removed.
> 
> The permanent home of Hamlib is here:
> 
> https://github.com/Hamlib/Hamlib
> 
> Mike W9MDB
> 
> 
> 
> 
> 
> 
> On Saturday, December 9, 2023 at 02:33:42 PM CST, Daniel Uppström via 
> wsjt-devel  wrote: 
> 
> 
> 
> 
> 
> Hi,
> When trying to build WSJT-X from source these days I cannot any longer access 
> the Hamlib fork:
> 
> git clone git://git.code.sf.net/u/bsomervi/hamlib src
> Cloning into 'src'...
> fatal: remote error: access denied or repository not exported: 
> /u/bsomervi/hamlib
> 
> Any ideas?
> 
> /Daniel SM6VFZ
> 
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> 
> 
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Re: [wsjt-devel] Cannot clone Hamlib fork

[Daniel Uppström via wsjt-devel]

Oh, that's unfortunate.
I thought this particular fork was necessary for WSJT-X and not the main
branch of Hamlib?

/SM6VFZ

Den sön 10 dec. 2023 19:22Black Michael via wsjt-devel <
wsjt-devel@lists.sourceforge.net> skrev:

> Since Bill is silent key that repository has been removed.
>
> The permanent home of Hamlib is here:
>
> https://github.com/Hamlib/Hamlib
>
> Mike W9MDB
>
>
>
>
>
>
> On Saturday, December 9, 2023 at 02:33:42 PM CST, Daniel Uppström via
> wsjt-devel  wrote:
>
>
>
>
>
> Hi,
> When trying to build WSJT-X from source these days I cannot any longer
> access the Hamlib fork:
>
> git clone git://git.code.sf.net/u/bsomervi/hamlib src
> Cloning into 'src'...
> fatal: remote error: access denied or repository not exported:
> /u/bsomervi/hamlib
>
> Any ideas?
>
> /Daniel SM6VFZ
>
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>
>
> ___
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Re: [wsjt-devel] Cannot clone Hamlib fork

[Black Michael via wsjt-devel]

Since Bill is silent key that repository has been removed.

The permanent home of Hamlib is here:

https://github.com/Hamlib/Hamlib

Mike W9MDB






On Saturday, December 9, 2023 at 02:33:42 PM CST, Daniel Uppström via 
wsjt-devel  wrote: 





Hi,
When trying to build WSJT-X from source these days I cannot any longer access 
the Hamlib fork:

git clone git://git.code.sf.net/u/bsomervi/hamlib src
Cloning into 'src'...
fatal: remote error: access denied or repository not exported: 
/u/bsomervi/hamlib

Any ideas?

/Daniel SM6VFZ

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Re: [wsjt-devel] WSJT noise estimates

[Joe Taylor via wsjt-devel]

Hi Joe,

On 12/9/2023 9:56 PM, w0fy--- via wsjt-devel wrote:
Been wondering how WSJT-X generates the noise power estimate it uses to 
calculate SNR for each FT8 signal.  Does it simply collect all the 
signals and noise over the bandwidth selected on the waterfall and call 
that the noise power level or does it take a quick snapshot of  the 
background noise level during the brief quiet period at the end of each 
15 second FT8 sequence? Or is it more complicated than that?


This question has been asked and answered many times on this and similar 
forums.  WSJT-X measures noise power by computing the spectrum of the 
receiver's output, averaged over the reception interval, and fitting a 
baseline to the regions that have no discernible signal present.  The 
resulting value -- effectively a noise power density, or power per unit 
bandwidth -- is then scaled to yield noise power in 2500 Hz bandwidth.


I am plagued with a S2 -S3 noise level on 6 meters nearly all the time 
that if not AWGN is pretty close to it.  10 meters is even worse. The 
DSP noise blanker in my TS590 will reduce it slightly. I estimate this 
is degrading my ability to decode FT8 signals on 6 by nearly 20 dB 
compared to the noise level generated by a 50 ohm resistor.  I don’t use 
an LNA ahead of the radio – would be pointless.  I don’t use the noise 
reduction feature in the radio either as it tends to lose very weak 
signals completely.


It's OK to use your receiver's noise blanker to remove impulsive noise.

Do NOT use "noise reduction" features, and do NOT use a receiver 
bandwidth narrower than about 2.5 kHz.  Wider bandwidths are even 
better, up to 4 or 5 kHz.  WSJT-X does all necessary narrow-band 
filtering in software.


-- 73, Joe, K1JT


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Re: [wsjt-devel] WSJT noise estimates

[w0fy--- via wsjt-devel]

Thanks for comments Reino and Andy.  My 20 dB degradation number was based on 
an actual measurement using FM mode on my radio.  Basically  injected a signal 
into the antenna feedline which was terminated with a 50 ohm load. Measured the 
receiver quieting sensitivity, then repeated the measurement with the antenna 
connected in place of the 50 ohm load. Noted the difference in input signal 
level required to produce a given amount of quieting. Although the receiver 
bandwidth is different, if we assume the noise is uniformly distributed over 
frequency the bandwidth difference should not affect the difference 
measurement. 

 

Think I’m going to redo that measurement using an actual locally generated FT8 
signal as soon as I figure out how to get enough attenuation on the FT8 signal 
and keep leakage from spoiling the measurement.   I don’t care about the SNR 
numbers reported, want to see if I can improve decoding sensitivity with 
additional filtering. Suffering from the frustration of others around me 
decoding stuff  I don’t!

 

From: Reino Talarmo via wsjt-devel  
Sent: Sunday, December 10, 2023 10:19 AM
To: 'WSJT software development' 
Cc: Reino Talarmo 
Subject: Re: [wsjt-devel] WSJT noise estimates

 

Hi Andy,

Interesting approach. But how you know that it really enhanced the signal 
detection?
The wanted signal is now close the wanted signal and that may disturb the S/N 
calculation and you will see a better S/N values with your method without a 
real better sensitivity. Possibly the only real comparison could be with two 
radios fed from the same antenna with a power divider (you may need a an 
amplifier before the power divider for compensating attenuation) and two 
instances of wsjt-x. Then a statistical study of success/failure rates could 
tell a real story.

 

Just my two pennies.

 

73, Reino OH3mA

 

From: Andrew Neumeier via wsjt-devel [ 
 
mailto:wsjt-devel@lists.sourceforge.net] 
Sent: Sunday, December 10, 2023 3:40 PM
To: w0fy--- via wsjt-devel <  
wsjt-devel@lists.sourceforge.net>
Cc: Andrew Neumeier <  ka2...@yahoo.com>
Subject: Re: [wsjt-devel] WSJT noise estimates

 

Joe,

 

Just a comment here.  I use FT8 frequently and almost always on 2 meters.  My 
interest is in weak signals.  I use a Omni VII here, with a transverter.  I 
have had some luck using my notch filter on very weak FT8

signals.  Setting the notch width at about 75hz, I have been using the edge of 
the filter to enhance the signals I am looking for.  So, the notch is not 
directly on the desired signal, but set a few hundred hertz from it, usually

below it.  Of course, placing the notch directly on the signal would erase it, 
but I don't use it that way.  I have worked a number of stations this way.  It 
took some playing around to get this to work, and it does not always

work, and one must see the signal first and have a decode failure, before 
turning to this remedy.  

 

Just my two cents.

 

Best of luck,

73,

Andy, ka2uqw

 

 

 

On Saturday, December 9, 2023 at 10:05:26 PM EST, w0fy--- via wsjt-devel < 
 wsjt-devel@lists.sourceforge.net> 
wrote: 

 

 

Been wondering how WSJT-X generates the noise power estimate it uses to 
calculate SNR for each FT8 signal.  Does it simply collect all the signals and 
noise over the bandwidth selected on the waterfall and call that the noise 
power level or does it take a quick snapshot of  the background noise level 
during the brief quiet period at the end of each 15 second FT8 sequence? Or is 
it more complicated than that?

 

I am plagued with a S2 -S3 noise level on 6 meters nearly all the time that if 
not AWGN is pretty close to it.  10 meters is even worse. The DSP noise blanker 
in my TS590 will reduce it slightly. I estimate this is degrading my ability to 
decode FT8 signals on 6 by nearly 20 dB compared to the noise level generated 
by a 50 ohm resistor.  I don’t use an LNA ahead of the radio – would be 
pointless.  I don’t use the noise reduction feature in the radio either as it 
tends to lose very weak signals completely. 

 

Wondering if I can use the DSP in my TS590 to narrow the receiver bandwidth to 
perhaps 300 -500 Hz around a known offset to help pick weak signals out of the 
noise? I realize that the WSJT program filters the audio into much narrower BW 
bins so all the receiver filtering can do is reduce the receiver gain reduction 
caused by the noise pumping up the AGC but that might be beneficial.  Likewise, 
would using the DSP notch to suppress a single strong local signal or birdie 
help since strong signals also reduce receiver gain?  Should I deselect the 
flatness option if I use these tools? Would narrowing the waterfall span help 
any since the program ignores anything outside that span? Would appreciate any 
insight you can share.

 

Joe W0FY

 

 

Re: [wsjt-devel] WSJT noise estimates

[Andrew Neumeier via wsjt-devel]

 Reino,
I really have no data to compare as you suggest, and the results are purely 
annecdotal.  

The way this got started was that on 2 meters I suffer from local rfi, usually 
these are suspected to be chargers in the vicinity.  In engaging filters I 
noticed the rfi become enhanced, by observingnearly imperceptible rfi become 
completely visible.  So, I wondered if I could do the same with a very weak 
signal.  In some cases, a non-decoding ft8 signal which is very light in color, 
often becomesdarker, nearly orange at times and decodes.  Using the method, I 
have worked quite a few stations otherwise impossible to decode.  And yes, the 
signal reading reported by WSJTX will change, sometimesdramatically.  As I 
posted earlier, the method is not foolproof, it doesn't always work.  QSB does 
not help the matter, of course.  

It's important to mention that I do this only on 2 meters.  Often the target 
signal is the only one on the waterfall so I can spend time zeroing in on it.  

I can only suggest that it be tried, maybe I'm wrong, but I use the method 
pretty regularly.
I have noticed the same results on Q65, but generally have not spent much time 
with it there.

73,Andy, ka2uqw


On Sunday, December 10, 2023 at 11:25:32 AM EST, Reino Talarmo via 
wsjt-devel  wrote:  
 
 
Hi Andy,

Interesting approach. But how you know that it really enhanced the signal 
detection?
The wanted signal is now close the wanted signal and that may disturb the S/N 
calculation and you will see a better S/N values with your method without a 
real better sensitivity. Possibly the only real comparison could be with two 
radios fed from the same antenna with a power divider (you may need a an 
amplifier before the power divider for compensating attenuation) and two 
instances of wsjt-x. Then a statistical study of success/failure rates could 
tell a real story.

  

Just my two pennies.

  

73, Reino OH3mA

  

From: Andrew Neumeier via wsjt-devel [mailto:wsjt-devel@lists.sourceforge.net] 
Sent: Sunday, December 10, 2023 3:40 PM
To: w0fy--- via wsjt-devel 
Cc: Andrew Neumeier 
Subject: Re: [wsjt-devel] WSJT noise estimates

  

Joe,

  

Just a comment here.  I use FT8 frequently and almost always on 2 meters.  My 
interest is in weak signals.  I use a Omni VII here, with a transverter.  I 
have had some luck using my notch filter on very weak FT8

signals.  Setting the notch width at about 75hz, I have been using the edge of 
the filter to enhance the signals I am looking for.  So, the notch is not 
directly on the desired signal, but set a few hundred hertz from it, usually

below it.  Of course, placing the notch directly on the signal would erase it, 
but I don't use it that way.  I have worked a number of stations this way.  It 
took some playing around to get this to work, and it does not always

work, and one must see the signal first and have a decode failure, before 
turning to this remedy.  

  

Just my two cents.

  

Best of luck,

73,

Andy, ka2uqw

  

  

  

On Saturday, December 9, 2023 at 10:05:26 PM EST, w0fy--- via wsjt-devel 
 wrote: 

  

  

Been wondering how WSJT-X generates the noise power estimate it uses to 
calculate SNR for each FT8 signal.  Does it simply collect all the signals and 
noise over the bandwidth selected on the waterfall and call that the noise 
power level or does it take a quick snapshot of  the background noise level 
during the brief quiet period at the end of each 15 second FT8 sequence? Or is 
it more complicated than that?

 

I am plagued with a S2 -S3 noise level on 6 meters nearly all the time that if 
not AWGN is pretty close to it.  10 meters is even worse. The DSP noise blanker 
in my TS590 will reduce it slightly. I estimate this is degrading my ability to 
decode FT8 signals on 6 by nearly 20 dB compared to the noise level generated 
by a 50 ohm resistor.  I don’t use an LNA ahead of the radio – would be 
pointless.  I don’t use the noise reduction feature in the radio either as it 
tends to lose very weak signals completely. 

 

Wondering if I can use the DSP in my TS590 to narrow the receiver bandwidth to 
perhaps 300 -500 Hz around a known offset to help pick weak signals out of the 
noise? I realize that the WSJT program filters the audio into much narrower BW 
bins so all the receiver filtering can do is reduce the receiver gain reduction 
caused by the noise pumping up the AGC but that might be beneficial.  Likewise, 
would using the DSP notch to suppress a single strong local signal or birdie 
help since strong signals also reduce receiver gain?  Should I deselect the 
flatness option if I use these tools? Would narrowing the waterfall span help 
any since the program ignores anything outside that span? Would appreciate any 
insight you can share.

 

Joe W0FY

 

 

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Re: [wsjt-devel] WSJT noise estimates

[Reino Talarmo via wsjt-devel]

Hi Andy,

Interesting approach. But how you know that it really enhanced the signal 
detection?
The wanted signal is now close the wanted signal and that may disturb the S/N 
calculation and you will see a better S/N values with your method without a 
real better sensitivity. Possibly the only real comparison could be with two 
radios fed from the same antenna with a power divider (you may need a an 
amplifier before the power divider for compensating attenuation) and two 
instances of wsjt-x. Then a statistical study of success/failure rates could 
tell a real story.

 

Just my two pennies.

 

73, Reino OH3mA

 

From: Andrew Neumeier via wsjt-devel [mailto:wsjt-devel@lists.sourceforge.net] 
Sent: Sunday, December 10, 2023 3:40 PM
To: w0fy--- via wsjt-devel 
Cc: Andrew Neumeier 
Subject: Re: [wsjt-devel] WSJT noise estimates

 

Joe,

 

Just a comment here.  I use FT8 frequently and almost always on 2 meters.  My 
interest is in weak signals.  I use a Omni VII here, with a transverter.  I 
have had some luck using my notch filter on very weak FT8

signals.  Setting the notch width at about 75hz, I have been using the edge of 
the filter to enhance the signals I am looking for.  So, the notch is not 
directly on the desired signal, but set a few hundred hertz from it, usually

below it.  Of course, placing the notch directly on the signal would erase it, 
but I don't use it that way.  I have worked a number of stations this way.  It 
took some playing around to get this to work, and it does not always

work, and one must see the signal first and have a decode failure, before 
turning to this remedy.  

 

Just my two cents.

 

Best of luck,

73,

Andy, ka2uqw

 

 

 

On Saturday, December 9, 2023 at 10:05:26 PM EST, w0fy--- via wsjt-devel 
mailto:wsjt-devel@lists.sourceforge.net> > 
wrote: 

 

 

Been wondering how WSJT-X generates the noise power estimate it uses to 
calculate SNR for each FT8 signal.  Does it simply collect all the signals and 
noise over the bandwidth selected on the waterfall and call that the noise 
power level or does it take a quick snapshot of  the background noise level 
during the brief quiet period at the end of each 15 second FT8 sequence? Or is 
it more complicated than that?

 

I am plagued with a S2 -S3 noise level on 6 meters nearly all the time that if 
not AWGN is pretty close to it.  10 meters is even worse. The DSP noise blanker 
in my TS590 will reduce it slightly. I estimate this is degrading my ability to 
decode FT8 signals on 6 by nearly 20 dB compared to the noise level generated 
by a 50 ohm resistor.  I don’t use an LNA ahead of the radio – would be 
pointless.  I don’t use the noise reduction feature in the radio either as it 
tends to lose very weak signals completely. 

 

Wondering if I can use the DSP in my TS590 to narrow the receiver bandwidth to 
perhaps 300 -500 Hz around a known offset to help pick weak signals out of the 
noise? I realize that the WSJT program filters the audio into much narrower BW 
bins so all the receiver filtering can do is reduce the receiver gain reduction 
caused by the noise pumping up the AGC but that might be beneficial.  Likewise, 
would using the DSP notch to suppress a single strong local signal or birdie 
help since strong signals also reduce receiver gain?  Should I deselect the 
flatness option if I use these tools? Would narrowing the waterfall span help 
any since the program ignores anything outside that span? Would appreciate any 
insight you can share.

 

Joe W0FY

 

 

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Re: [wsjt-devel] WSJT noise estimates

[Andrew Neumeier via wsjt-devel]

 Joe,
Just a comment here.  I use FT8 frequently and almost always on 2 meters.  My 
interest is in weak signals.  I use a Omni VII here, with a transverter.  I 
have had some luck using my notch filter on very weak FT8signals.  Setting the 
notch width at about 75hz, I have been using the edge of the filter to enhance 
the signals I am looking for.  So, the notch is not directly on the desired 
signal, but set a few hundred hertz from it, usuallybelow it.  Of course, 
placing the notch directly on the signal would erase it, but I don't use it 
that way.  I have worked a number of stations this way.  It took some playing 
around to get this to work, and it does not alwayswork, and one must see the 
signal first and have a decode failure, before turning to this remedy.  

Just my two cents.
Best of luck,73,Andy, ka2uqw


On Saturday, December 9, 2023 at 10:05:26 PM EST, w0fy--- via wsjt-devel 
 wrote:  
 
 
Been wondering how WSJT-X generates the noise power estimate it uses to 
calculate SNR for each FT8 signal.  Does it simply collect all the signals and 
noise over the bandwidth selected on the waterfall and call that the noise 
power level or does it take a quick snapshot of  the background noise level 
during the brief quiet period at the end of each 15 second FT8 sequence? Or is 
it more complicated than that?

  

I am plagued with a S2 -S3 noise level on 6 meters nearly all the time that if 
not AWGN is pretty close to it.  10 meters is even worse. The DSP noise blanker 
in my TS590 will reduce it slightly. I estimate this is degrading my ability to 
decode FT8 signals on 6 by nearly 20 dB compared to the noise level generated 
by a 50 ohm resistor.  I don’t use an LNA ahead of the radio – would be 
pointless.  I don’t use the noise reduction feature in the radio either as it 
tends to lose very weak signals completely. 

  

Wondering if I can use the DSP in my TS590 to narrow the receiver bandwidth to 
perhaps 300 -500 Hz around a known offset to help pick weak signals out of the 
noise? I realize that the WSJT program filters the audio into much narrower BW 
bins so all the receiver filtering can do is reduce the receiver gain reduction 
caused by the noise pumping up the AGC but that might be beneficial.  Likewise, 
would using the DSP notch to suppress a single strong local signal or birdie 
help since strong signals also reduce receiver gain?  Should I deselect the 
flatness option if I use these tools? Would narrowing the waterfall span help 
any since the program ignores anything outside that span? Would appreciate any 
insight you can share.

  

Joe W0FY

  

  
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Re: [wsjt-devel] WSJT noise estimates

[Reino Talarmo via wsjt-devel]

Hi Joe, 
Some quick comments in-line.

73, Reino OH3mA

> Sent: Sunday, December 10, 2023 4:56 AM
> Subject: [wsjt-devel] WSJT noise estimates

> Been wondering how WSJT-X generates the noise power
estimate it uses to calculate SNR for each FT8 signal. 
Does it simply collect all the signals and noise over
the bandwidth selected on the waterfall and call that
the noise power level or does it take a quick snapshot
of  the background noise level during the brief quiet
period at the end of each 15 second FT8 sequence? Or is
it more complicated than that?
3mA: The S/N calculation process is pretty complicated.
It estimates noise over the whole receiver bandwidth and
uses 2500 Hz as the reference bandwidth. Some other
implementations try to calculate S/N over the individual
signal bandwidth, 50Hz, and the values are not directly
comparable.

> I am plagued with a S2 -S3 noise level on 6 meters
nearly all the time that if not AWGN is pretty close to
it.  10 meters is even worse. The DSP noise blanker in
my TS590 will reduce it slightly. I estimate this is
degrading my ability to decode FT8 signals on 6 by
nearly 20 dB compared to the noise level generated by a
50 ohm resistor.  I don’t use an LNA ahead of the radio
– would be pointless.  I don’t use the noise reduction
feature in the radio either as it tends to lose very
weak signals completely. 
3mA: Noise blanker may help only, if the noise have high
and short peaks and the noise is cancelled e.g. limited
at a wide bandwidth point of the receiver chain. On AWGN
it does not help. Then the resulting distortion noise is
distributed over a wide frequency range. Your assumption
about the degradation may be a bit pessimistic,
depending on the noise type, S2 - S3 is quite low
compared what is typical on lower HF.

> Wondering if I can use the DSP in my TS590 to narrow
the receiver bandwidth to perhaps 300 -500 Hz around a
known offset to help pick weak signals out of the noise?
I realize that the WSJT program filters the audio into
much narrower BW bins so all the receiver filtering can
do is reduce the receiver gain reduction caused by the
noise pumping up the AGC but that might be beneficial.  
3mA: The additional receiver bandwidth reduction
improves the calculated S/N values as there is less
noise. But the decoding sensitivity does not usually
improve as long as the linearity of the receiver chain
is kept. There is some S/N calculation oddities at the
edges of a narrow bandwidth. I don't know the actual
reason, but I have recorded up to 40 dB additional
variations of S/N values in a comparison of the same
messages between narrow and wide bandwidths. 

> Likewise, would using the DSP notch to suppress a
single strong local signal or birdie help since strong
signals also reduce receiver gain?  
3mA: That seems to help. Especially, when the disturbing
signal is not very close to the wanted signal. 

> Should I deselect the flatness option if I use these
tools? 
3mA: To my knowledge the flatness option is only for
waterfall display, not for the decoding process.
 
Would narrowing the waterfall span help any since the
program ignores anything outside that span? 
3mA: That is about equivalent as usage of a narrow
filter. If signals outside of the waterfall are not
causing distortion noise (overdriving receiver), then
there will be an apparent S/N improvement, but not a
real decoding improvement. There is another possible
decoding improvement as there are less signal candidates
to process, Decoding is only attempted on frequencies
inside the waterfall. Well at least in principle, I have
seem rear instances, where also signal outside the
waterfall has been decoded.

> Would appreciate any insight you can share.

Joe W0FY

PS. 3mA i.e. is 3 milliamps, my local nickname.



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