Topics

S-meter in SDR-console 2.3 and vers.3

Hubert HB9JND
 

Hello Uli

I think that the S meter simply displays the highest value of all FFT lines within the pass filter.
I am also of the opinion that it should display the power sum of all FFT lines within the pass filter.
But probably Simon has currently other priorities.

73, Hubert

 

Von: sdr-radio-com@... [mailto:sdr-radio-com@...]
Gesendet: Mittwoch, 28. September 2016 09:15
An: sdr
-radio-com@...
Betreff: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Hello,
I have a question:
- can someone tell me, what the S-meter in SDR-console Vers. 2.3 and Vers. 3 is actually showing ?

If I simply disconnect the antenna from my SDR (so the spectrum indicates only noisefloor and no signals), I would expect the S-meter is showing the noisepower in the selected bandwidth.
But when I change the bandwidth the S-Meter does not change !!!

Usually we use the S-meter in a receiver to measure the fieldstrength. This is the total power in the reception bandwith delivered to the 50Ohm input of the rx. (relative to 1mW@50Ohm = def. of dBm)

But this is not what SDR-console S-meter is doing !!
So what does it ? 
May be this question only Simon can answer....

Background:
I am currently busy to relocate my CW-skimmer to a new location 50km from my home on a remote place. To judge the noise pollution in comparison with other QTH-alternatives, I want to measure the noisefloor in absolute dBm in CW and SSB bandwidth....
But unfortunately I realize, that SDR-console cannot measure the noisepower/fieldstrength as I expected...

Has anyone a better suggestion ?
What is the purpose of the S-meter (dbm indication) of SDR-console - what does it exactly? Seems to sample and hold peak samples ?!?

Many thanks for information.

Ulli, ON5KQ

 

Simon Brown
 

My option is that a S meter displays the strongest signal in the passband, just like a normal Ham radio does.

 

If you want an alternative then tell me exactly what’s wanted – a clear specification please.

 

Simon Brown, GK4ELI
http://sdr-radio.com

 

From: sdr-radio-com@... [mailto:sdr-radio-com@...]
Sent: 28 September 2016 08:58
To: sdr-radio-com@...
Subject: AW: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Hello Uli

I think that the S meter simply displays the highest value of all FFT lines within the pass filter.
I am also of the opinion that it should display the power sum of all FFT lines within the pass filter.
But probably Simon has currently other priorities.

73, Hubert


 

Von: sdr-radio-com@... [mailto:sdr-radio-com@...]
Gesendet: Mittwoch, 28. September 2016 09:15
An: sdr-radio-com@...

Betreff: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Hello,
I have a question:
- can someone tell me, what the S-meter in SDR-console Vers. 2.3 and Vers. 3 is actually showing ?

If I simply disconnect the antenna from my SDR (so the spectrum indicates only noisefloor and no signals), I would expect the S-meter is showing the noisepower in the selected bandwidth.
But when I change the bandwidth the S-Meter does not change !!!

Usually we use the S-meter in a receiver to measure the fieldstrength. This is the total power in the reception bandwith delivered to the 50Ohm input of the rx. (relative to 1mW@50Ohm = def. of dBm)

But this is not what SDR-console S-meter is doing !!
So what does it ? 
May be this question only Simon can answer....

Background:
I am currently busy to relocate my CW-skimmer to a new location 50km from my home on a remote place. To judge the noise pollution in comparison with other QTH-alternatives, I want to measure the noisefloor in absolute dBm in CW and SSB bandwidth....
But unfortunately I realize, that SDR-console cannot measure the noisepower/fieldstrength as I expected...

Has anyone a better suggestion ?
What is the purpose of the S-meter (dbm indication) of SDR-console - what does it exactly? Seems to sample and hold peak samples ?!?

Many thanks for information.

Ulli, ON5KQ

 

ON5KQ
 

Simon,
Noisemeasurement with a spectrum analyser is actually what I want the SDR for. In that case not to listen to BBC...

Here is an application note from Agilent on this subject..
http://www.ab4oj.com/test/docs/5966-4008E.pdf

I realise, that almost all SDR's show different S-meter values, when trying to measure Noise intensity. That was the reason why I asked about the definition in SDR-console
(of coase I would need to ask all the other undocumented S-meters in other software also...hi)

So best is probably to just keep taking screenshots and compare spectrum visually and not to bother about dBm value..

As SDR-console taking max sample values only, the dBm values are usually 10db or more lower than other SDR software/hardware combinations... one need to have that in mind...

Ulli, ON5KQ

mcayton@...
 

Gents,

Simon is correct, an S-meter should display the strongest signal in the passband, no more and no less.

Let us compare two examples of momentary snapshots of signals - one is a CW signal of S-9 strength, and the other is a SSB voice signal with a strongest momentary peak at S-9 and a weakest same-instant low point elsewhere in the passband of S-6.  The S-meter in both cases should report S-9, since that is the peak signal strength in both instances.  In the SSB case, it doesn't matter what the signal strength is at any other spot in the passband, the S-meter should read S-9 because that's the max strength measured anywhere in the passband.  There should be no effort to "sum" any other portion of passband signal to the strongest measured signal.  If there was any "summing" being done, the S-meter would always be pegged on any moderately strong SSB signal (but of course that's not the case).

The S-meter should simply report the strongest signal measured anywhere in the passband.  That's the way an S-meter works on any radio.  That's the S-meter's only job, and that's always been it's only job, on any receiver.

Regards,

Mark  KF5VQY

ON5KQ
 

Mark,
in the case of only showing the max level of a reception signal we have no information about the actual QUALITY of the reception - the signal to noise ratio.
That said, I think it is necessary to be able also to judge on noise level, so be able to measure noise intensity compared to the signal level.

Otherwise one could be completely blind to think that a 5cm active whip with enough pre-amplification to provide S9 peaks could hear as good as a 350m Beverage antenna in the desired direction.

How can I judge my receiving antenna's, if I only have information about about peak signal values...

It is even worse: If you take different SDR-radios on different software the noise floor, which the spectrum shows is different depending on what software you are using... (same FFT parameters, etc.   as far as the software is telling you) - there is no standard in amateur-equipment HOW to measure noise.
That is why Simon correctly asks WHAT the detailed standards should be...
Unfortunately we only have standards on noise measurement in the professional telecom world, often with the idea to support measurement with digital transmission applications.

As I want to build a remote location for CW-skimmer purely for receiving, I am only interested in maximise S/N ratio initially... With only information on peak levels I am out of control...

Ulli, ON5KQ

Hubert HB9JND
 

Simon

Ok, I'll like to try in the next few days to specify the correct technical function of a S-meter.
I think it is not a question of my personal opinion, but simply the product of the physical relationships.

Hubert

 

 

Von: sdr-radio-com@... [mailto:sdr-radio-com@...]
Gesendet: Mittwoch, 28. September 2016 18:47
An: sdr-radio-com@...
Betreff: RE: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

My option is that a S meter displays the strongest signal in the passband, just like a normal Ham radio does.

 

If you want an alternative then tell me exactly what’s wanted – a clear specification please.

 

Simon Brown, GK4ELI
http://sdr-radio.com

 

From: sdr-radio-com@... [mailto:sdr-radio-com@...]
Sent: 28 September 2016 08:58
To: sdr-radio-com@...
Subject: AW: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Hello Uli

I think that the S meter simply displays the highest value of all FFT lines within the pass filter.
I am also of the opinion that it should display the power sum of all FFT lines within the pass filter.
But probably Simon has currently other priorities.

73, Hubert



 

Von: sdr-radio-com@... [mailto:sdr-radio-com@...]
Gesendet: Mittwoch, 28. September 2016 09:15
An: sdr-radio-com@...

Betreff: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Hello,
I have a question:
- can someone tell me, what the S-meter in SDR-console Vers. 2.3 and Vers. 3 is actually showing ?

If I simply disconnect the antenna from my SDR (so the spectrum indicates only noisefloor and no signals), I would expect the S-meter is showing the noisepower in the selected bandwidth.
But when I change the bandwidth the S-Meter does not change !!!

Usually we use the S-meter in a receiver to measure the fieldstrength. This is the total power in the reception bandwith delivered to the 50Ohm input of the rx. (relative to 1mW@50Ohm = def. of dBm)

But this is not what SDR-console S-meter is doing !!
So what does it ? 
May be this question only Simon can answer....

Background:
I am currently busy to relocate my CW-skimmer to a new location 50km from my home on a remote place. To judge the noise pollution in comparison with other QTH-alternatives, I want to measure the noisefloor in absolute dBm in CW and SSB bandwidth....
But unfortunately I realize, that SDR-console cannot measure the noisepower/fieldstrength as I expected...

Has anyone a better suggestion ?
What is the purpose of the S-meter (dbm indication) of SDR-console - what does it exactly? Seems to sample and hold peak samples ?!?

Many thanks for information.

Ulli, ON5KQ

 

Alan <g4zfq@...>
 

Original Message -----
Subject: RE: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3



As I want to build a remote location for CW-skimmer purely for receiving, I am only interested in maximise S/N ratio initially... With only information on peak levels I am out of control...
Ulli,

In it's developing state maybe SDR-Radio is not the best for measurements I think Linrad gives a SNR readout. HDSDR is good for measuring.
But for system improvement with just relative measurements just keep at settings the same and read off the waterfall or spectrum.
For actual calibration there is the Elecraft XG series.

73 Alan G4ZFQ

Simon Brown
 

Hubert,

 

Let me make this very clear: the Signal Meter (S-meter) shows the peak signal level, it is not designed to show Signal to Noise. What you expect is a different signal indication – I am interested in what you want to see but the S-meter logic you see now will remain as it is. I have no problem in writing an alternate metering interface.

 

Simon Brown, GK4ELI
http://sdr-radio.com

 

From: sdr-radio-com@... [mailto:sdr-radio-com@...]
Sent: 29 September 2016 07:14
To: sdr-radio-com@...
Subject: AW: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Simon

Ok, I'll like to try in the next few days to specify the correct technical function of a S-meter.
I think it is not a question of my personal opinion, but simply the product of the physical relationships.

Hubert

 

 

Von: sdr-radio-com@... [mailto:sdr-radio-com@...]
Gesendet: Mittwoch, 28. September 2016 18:47
An: sdr-radio-com@...
Betreff: RE: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

My option is that a S meter displays the strongest signal in the passband, just like a normal Ham radio does.

 

If you want an alternative then tell me exactly what’s wanted – a clear specification please.

 

Simon Brown, GK4ELI
http://sdr-radio.com

 

From: sdr-radio-com@... [mailto:sdr-radio-com@...]
Sent: 28 September 2016 08:58
To: sdr-radio-com@...
Subject: AW: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Hello Uli

I think that the S meter simply displays the highest value of all FFT lines within the pass filter.
I am also of the opinion that it should display the power sum of all FFT lines within the pass filter.
But probably Simon has currently other priorities.

73, Hubert




 

Von: sdr-radio-com@... [mailto:sdr-radio-com@...]
Gesendet: Mittwoch, 28. September 2016 09:15
An: sdr-radio-com@...

Betreff: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Hello,
I have a question:
- can someone tell me, what the S-meter in SDR-console Vers. 2.3 and Vers. 3 is actually showing ?

If I simply disconnect the antenna from my SDR (so the spectrum indicates only noisefloor and no signals), I would expect the S-meter is showing the noisepower in the selected bandwidth.
But when I change the bandwidth the S-Meter does not change !!!

Usually we use the S-meter in a receiver to measure the fieldstrength. This is the total power in the reception bandwith delivered to the 50Ohm input of the rx. (relative to 1mW@50Ohm = def. of dBm)

But this is not what SDR-console S-meter is doing !!
So what does it ? 
May be this question only Simon can answer....

Background:
I am currently busy to relocate my CW-skimmer to a new location 50km from my home on a remote place. To judge the noise pollution in comparison with other QTH-alternatives, I want to measure the noisefloor in absolute dBm in CW and SSB bandwidth....
But unfortunately I realize, that SDR-console cannot measure the noisepower/fieldstrength as I expected...

Has anyone a better suggestion ?
What is the purpose of the S-meter (dbm indication) of SDR-console - what does it exactly? Seems to sample and hold peak samples ?!?

Many thanks for information.

Ulli, ON5KQ

 

Simon Brown
 

Thank-you J

 

Simon Brown, GK4ELI
http://sdr-radio.com

 

From: sdr-radio-com@... [mailto:sdr-radio-com@...]
Sent: 28 September 2016 21:24
To: sdr-radio-com@...
Subject: RE: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Gents,

 

Simon is correct, an S-meter should display the strongest signal in the passband, no more and no less.

 

Let us compare two examples of momentary snapshots of signals - one is a CW signal of S-9 strength, and the other is a SSB voice signal with a strongest momentary peak at S-9 and a weakest same-instant low point elsewhere in the passband of S-6.  The S-meter in both cases should report S-9, since that is the peak signal strength in both instances.  In the SSB case, it doesn't matter what the signal strength is at any other spot in the passband, the S-meter should read S-9 because that's the max strength measured anywhere in the passband.  There should be no effort to "sum" any other portion of passband signal to the strongest measured signal.  If there was any "summing" being done, the S-meter would always be pegged on any moderately strong SSB signal (but of course that's not the case).

 

The S-meter should simply report the strongest signal measured anywhere in the passband.  That's the way an S-meter works on any radio.  That's the S-meter's only job, and that's always been it's only job, on any receiver.



Regards,



Mark  KF5VQY



Simon Brown
 

Hah,

 

An excellent PDF – thanks.

 

Simon Brown, GK4ELI
http://sdr-radio.com

 

From: sdr-radio-com@... [mailto:sdr-radio-com@...]
Sent: 28 September 2016 20:48
To: sdr-radio-com@...
Subject: RE: [sdr-radio-com] S-meter in SDR-console 2.3 and vers.3

 

 

Simon,
Noisemeasurement with a spectrum analyser is actually what I want the SDR for. In that case not to listen to BBC...

Here is an application note from Agilent on this subject..
http://www.ab4oj.com/test/docs/5966-4008E.pdf

I realise, that almost all SDR's show different S-meter values, when trying to measure Noise intensity. That was the reason why I asked about the definition in SDR-console
(of coase I would need to ask all the other undocumented S-meters in other software also...hi)

So best is probably to just keep taking screenshots and compare spectrum visually and not to bother about dBm value..

As SDR-console taking max sample values only, the dBm values are usually 10db or more lower than other SDR software/hardware combinations... one need to have that in mind...

Ulli, ON5KQ