SNR meter, bandwidth and gain adjustment for transverters


Conrad, PA5Y
 

Hello Simon.

I asked about the main dB scale in the receiver window and how it relates to bandwidth, you did not reply. I see that the question has been asked before, What exactly does it display? Also, the SNR reading does not change with filter BW, surely it should. How does the SNR meter work? For instance, it shows a positive SNR where there is no signal present in the filter passband so perhaps it is finding the max a signal in a wide passband? It would be better if it only looked inside the filter BW.

Finally, as a feature request would it be possible to have some manual gain adjustment to compensate for transverters and LNAs?

Many thanks

Conrad PA5Y


Simon Brown
 

I have answered this before, also I cannot answer all questions as soon as they are asked, I do have my own priorities and a life away from coding.

 

  • The dB value comes directly from the FFT, for a RX signal it's the peak value of FFT bins inside the filter.
    • FFT bins are affected by Windowing and selected FFT resolution, so different windowing / resolution will affect noise.
  • SNR is peak as above, noise is the average of the lowest 10% (I think) of FFT bins displayed in the main window.
  • When there's no visible signal there will still be a peak as you observe and noise is not uniform.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 03 July 2021 09:02
To: main@SDR-Radio.groups.io
Subject: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

Hello Simon.

 

I asked about the main dB scale in the receiver window and how it relates to bandwidth, you did not reply. I see that the question has been asked before, What exactly does it display? Also, the SNR reading does not change with filter BW, surely it should. How does the SNR meter work? For instance, it shows a positive SNR where there is no signal present in the filter passband so perhaps it is finding the max a signal in a wide passband? It would be better if it only looked inside the filter BW.

 

Finally, as a feature request would it be possible to have some manual gain adjustment to compensate for transverters and LNAs?

 

Many thanks

 

Conrad PA5Y

 

 

 

 

 

 

 

 


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Conrad, PA5Y
 

Hi Simon, thanks.

 

I will find these parameters and experiment.

 

Regards

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown via groups.io
Sent: 03 July 2021 10:11
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

I have answered this before, also I cannot answer all questions as soon as they are asked, I do have my own priorities and a life away from coding.

 

  • The dB value comes directly from the FFT, for a RX signal it's the peak value of FFT bins inside the filter.
    • FFT bins are affected by Windowing and selected FFT resolution, so different windowing / resolution will affect noise.
  • SNR is peak as above, noise is the average of the lowest 10% (I think) of FFT bins displayed in the main window.
  • When there's no visible signal there will still be a peak as you observe and noise is not uniform.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y
Sent: 03 July 2021 09:02
To: main@SDR-Radio.groups.io
Subject: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

Hello Simon.

 

I asked about the main dB scale in the receiver window and how it relates to bandwidth, you did not reply. I see that the question has been asked before, What exactly does it display? Also, the SNR reading does not change with filter BW, surely it should. How does the SNR meter work? For instance, it shows a positive SNR where there is no signal present in the filter passband so perhaps it is finding the max a signal in a wide passband? It would be better if it only looked inside the filter BW.

 

Finally, as a feature request would it be possible to have some manual gain adjustment to compensate for transverters and LNAs?

 

Many thanks

 

Conrad PA5Y

 

 

 

 

 

 

 

 

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Max
 

On Sat, Jul 3, 2021 at 09:01 AM, Conrad, PA5Y wrote:
Finally, as a feature request would it be possible to have some manual gain adjustment to compensate for transverters and LNAs?
Hi Conrad

I am no expert..... in fact very far from it, but have you seen the Visual Gain setting? It's available on all the rigs I use with SDRC (HL2, RSP2Pro, RTL-SDR V3). Not sure if Simon has implemented it for every radio that can be used with SDRC as it's in different place depending on the radio? Here it is for HL2 and RSP2Pro:

   

Can calibrate for zero signal (i.e.antenna disconnected). Is the feature you are alluding to?

73

Max


Simon Brown
 

Max,

 

Depends on the radio of course…

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Max
Sent: 03 July 2021 09:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

On Sat, Jul 3, 2021 at 09:01 AM, Conrad, PA5Y wrote:

Finally, as a feature request would it be possible to have some manual gain adjustment to compensate for transverters and LNAs?

Hi Conrad

I am no expert..... in fact very far from it, but have you seen the Visual Gain setting? It's available on all the rigs I use with SDRC (HL2, RSP2Pro, RTL-SDR V3). Not sure if Simon has implemented it for every radio that can be used with SDRC as it's in different place depending on the radio? Here it is for HL2 and RSP2Pro:

   

Can calibrate for zero signal (i.e.antenna disconnected). Is the feature you are alluding to?

73

Max


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Conrad, PA5Y
 

Hello Max, not quite at least I don’t think so. Does this affect the metering? But thanks, I will have a play around when I have time later. I was thinking of something that allows calibration to a known input level. So I put -30dBm in and can read that directly on the meter as -30dBm.

 

Regards

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Max via groups.io
Sent: 03 July 2021 10:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

On Sat, Jul 3, 2021 at 09:01 AM, Conrad, PA5Y wrote:

Finally, as a feature request would it be possible to have some manual gain adjustment to compensate for transverters and LNAs?

Hi Conrad

I am no expert..... in fact very far from it, but have you seen the Visual Gain setting? It's available on all the rigs I use with SDRC (HL2, RSP2Pro, RTL-SDR V3). Not sure if Simon has implemented it for every radio that can be used with SDRC as it's in different place depending on the radio? Here it is for HL2 and RSP2Pro:

   

Can calibrate for zero signal (i.e.antenna disconnected). Is the feature you are alluding to?

73

Max


Max
 

On Sat, Jul 3, 2021 at 10:04 AM, Conrad, PA5Y wrote:
Hello Max, not quite at least I don’t think so. Does this affect the metering?
Simon, yes, that's what I was not sure about!

Conrad...... if you have the Visual Gain feature for your radio, yes it does. What is (are) the radio(s)?

Max


Conrad, PA5Y
 

Hello Max I am using a Perseus, where do I find it if it is there?

 

Regards

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Max via groups.io
Sent: 03 July 2021 11:19
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

On Sat, Jul 3, 2021 at 10:04 AM, Conrad, PA5Y wrote:

Hello Max, not quite at least I don’t think so. Does this affect the metering?

Simon, yes, that's what I was not sure about!

Conrad...... if you have the Visual Gain feature for your radio, yes it does. What is (are) the radio(s)?

Max


Conrad, PA5Y
 

I don’t think that I have that, I have the radio pane docked and I do not see it.

 

Regards

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Conrad, PA5Y via groups.io
Sent: 03 July 2021 11:20
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

Hello Max I am using a Perseus, where do I find it if it is there?

 

Regards

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Max via groups.io
Sent: 03 July 2021 11:19
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

On Sat, Jul 3, 2021 at 10:04 AM, Conrad, PA5Y wrote:

Hello Max, not quite at least I don’t think so. Does this affect the metering?

Simon, yes, that's what I was not sure about!

Conrad...... if you have the Visual Gain feature for your radio, yes it does. What is (are) the radio(s)?

Max


jdow
 

The signal level meter gives a rough number for the 59 boys. It bears a rough connection to reality. It can be spoofed fairly easily with a tone modulating an NFM signal. But, people seem to like it. The purist in me regards it as a joke.

Normally speaking on SDRs the main dB scale is dBfs. That is dB relative to a single signal that gives a sinewave peak exactly the size of the A/D minumum to maximum values. Simon has some other stuff in there. But that's just to facilitate "calibration." You have to calibrate it if you want any meaningful metric reality. AND the display is probably based on power in a bandwidth corresponding to a pixel on the display. Don't even TRY to use it to read a noise figure. That technique is weak. And Simon's implementation is apparently intentionally undocumented.

{^_^}

On 20210703 01:01:37, Conrad, PA5Y wrote:
Hello Simon.

I asked about the main dB scale in the receiver window and how it relates to bandwidth, you did not reply. I see that the question has been asked before, What exactly does it display? Also, the SNR reading does not change with filter BW, surely it should. How does the SNR meter work? For instance, it shows a positive SNR where there is no signal present in the filter passband so perhaps it is finding the max a signal in a wide passband? It would be better if it only looked inside the filter BW.

Finally, as a feature request would it be possible to have some manual gain adjustment to compensate for transverters and LNAs?

Many thanks 

Conrad PA5Y











Max
 

On Sat, Jul 3, 2021 at 10:22 AM, Conrad, PA5Y wrote:

I don’t think that I have that, I have the radio pane docked and I do not see it.

 

Regards

 

Conrad

According to this post, yes it does:

https://forum.sdr-radio.com:4499/viewtopic.php?f=18&t=916



Max


Alan G4ZFQ
 

The signal level meter gives a rough number for the 59 boys.
I expected Joanne to make a comment:-)
There was a discussion a few months back where it was decided there was better software for scientific measurements.
You may find it a failing but there are so many other features in Simon's software that are not available elsewhere.

Alan


Conrad, PA5Y
 

Hello Max, I do not know how to get those options on the ribbon but I did find visual gain in the radio configuration tab. I am using v3.0.26, setting the gain to -20dB gives a close approximation. When Simon gets back I am sure that he will explain what I need to do.

 

Regards

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Max via groups.io
Sent: 03 July 2021 12:28
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

On Sat, Jul 3, 2021 at 10:22 AM, Conrad, PA5Y wrote:

I don’t think that I have that, I have the radio pane docked and I do not see it.

 

Regards

 

Conrad

According to this post, yes it does:

https://forum.sdr-radio.com:4499/viewtopic.php?f=18&t=916



Max


Conrad, PA5Y
 

Hi Alan, sorry I was not moaning, I just wanted to know what could be done. I use Linrad for measurements but really like the UI, appearance and stability of SDR console. I use it in conjunction with my K3S and transverters and for that purpose it is absolutely perfect. Off outside to do more antenna work.

Regards

Conrad

-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Alan G4ZFQ via groups.io
Sent: 03 July 2021 12:40
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters


> The signal level meter gives a rough number for the 59 boys.

I expected Joanne to make a comment:-)
There was a discussion a few months back where it was decided there was better software for scientific measurements.
You may find it a failing but there are so many other features in Simon's software that are not available elsewhere.

Alan


Simon Brown
 

Actually,

The relative dB readings will be *very* accurate. I only use SNR these days, occasionally just dB.

Simon Brown, G4ELI
https://www.sdr-radio.com

-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Alan G4ZFQ
Sent: 03 July 2021 11:40
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters


> The signal level meter gives a rough number for the 59 boys.

I expected Joanne to make a comment:-)
There was a discussion a few months back where it was decided there was better software for scientific measurements.
You may find it a failing but there are so many other features in Simon's software that are not available elsewhere.

Alan









--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Max
 
Edited

On Sat, Jul 3, 2021 at 11:46 AM, Conrad, PA5Y wrote:
Hello Max, I do not know how to get those options on the ribbon but I did find visual gain in the radio configuration tab. I am using v3.0.26
Hi Conrad

Not at all sure why you would be using 3.0.26? We're all on 3.0.28 now (released couple days ago). You really do need to use latest version. Simon is constantly working on it (yes, I do mean CONSTANTLY, as the man does not seem to sleep!) and adding highly effective tweaks almost daily to the test version. Remember he is only one person. What he has achieved with SDRC from the hands and brain of one man is nothing short of amazing. And also remember he makes it available  FREE although also consider a donation. Most of us (I hope) do. I only mention this as I know Simon will not:

https://www.sdr-radio.com/download#Donate

Anyway, at the least I suggest you do immediate update to 3.0.28. You should see some nice surprises!

https://www.sdr-radio.com/download

73

Max


Conrad, PA5Y
 

Will do!

 

Conrad

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Max via groups.io
Sent: 03 July 2021 13:51
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

[Edited Message Follows]
[Reason: Fix url]

On Sat, Jul 3, 2021 at 11:46 AM, Conrad, PA5Y wrote:

Hello Max, I do not know how to get those options on the ribbon but I did find visual gain in the radio configuration tab. I am using v3.0.26

Hi Conrad

Not at all sure why you would be using 3.0.26? We're all on 3.0.28 now (released couple days ago). You really do need to use latest version. Simon is constantly working on it (yes, I do mean CONSTANTLY, as the man does not seem to sleep!) and adding highly effective tweaks almost daily to the test version. Remember he is only one person. What he has achieved with SDRC from the hands and brain of one man is nothing short of amazing. And also remember he makes it available  FREE although also consider a donation. Most of us (I hope) do. I only mention this as I know Simon will not:

https://www.sdr-radio.com/download#Donate

Anyway, at the least I suggest you do immediate update to 3.0.28. You should see some nice surprises!

https://www.sdr-radio.com/download

73

Max


Max
 

Simon. My own post reminded me to send some emergency top-up beer money! Enjoy.

73

Max


jdow
 

SDRC is "fashionably" misperforming with regards to signal level measurement, perhaps to stop some other questions about signal level measurement.

{^_-}

On 20210703 03:48:43, Conrad, PA5Y wrote:
Hi Alan, sorry I was not moaning, I just wanted to know what could be done. I use Linrad for measurements but really like the UI, appearance and stability of SDR console. I use it in conjunction with my K3S and transverters and for that purpose it is absolutely perfect. Off outside to do more antenna work.

Regards 

Conrad

-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Alan G4ZFQ via groups.io
Sent: 03 July 2021 12:40
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters


 > The signal level meter gives a rough number for the 59 boys.

I expected Joanne to make a comment:-)
There was a discussion a few months back where it was decided there was better software for scientific measurements.
You may find it a failing but there are so many other features in Simon's software that are not available elsewhere.

Alan












Conrad, PA5Y
 

I have been doing some experimenting and based on my experience with other SDRs I still don’t understand what is going on. Comparative measurements are fine, but it appears that I cannot really use it as I would like to. However, as a band scope to use in conjunction with my K3S it is excellent. The ergonomics are great.

 

Regards

 

Conrad PA5Y

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow via groups.io
Sent: 03 July 2021 23:02
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters

 

SDRC is "fashionably" misperforming with regards to signal level measurement, perhaps to stop some other questions about signal level measurement.

{^_-}

On 20210703 03:48:43, Conrad, PA5Y wrote:

Hi Alan, sorry I was not moaning, I just wanted to know what could be done. I use Linrad for measurements but really like the UI, appearance and stability of SDR console. I use it in conjunction with my K3S and transverters and for that purpose it is absolutely perfect. Off outside to do more antenna work.
 
Regards 
 
Conrad
 
-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Alan G4ZFQ via groups.io
Sent: 03 July 2021 12:40
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters
 
 
 > The signal level meter gives a rough number for the 59 boys.
 
I expected Joanne to make a comment:-)
There was a discussion a few months back where it was decided there was better software for scientific measurements.
You may find it a failing but there are so many other features in Simon's software that are not available elsewhere.
 
Alan