Attenuation


vince battle
 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


Simon Brown
 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation
 
Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 

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


vince battle
 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


--

- + - + -

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

 


Simon Brown
 

OK,

Some of these radios have fixed attenuation options, for example NetSDR. HF+ - I'll have to check.

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 23 November 2022 15:34
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Attenuation
 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


--

- + - + -

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

 


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


Siegfried Jackstien
 

don´t you have also "visual gain" in all sdr used?? that could be done in 1 db steps so finetune of any sdr to correct readings should be possible

if no visual gain in all sdr setups under "radio" settings ... then you could add it where that is missing

rtl for example has fine steps (but not exactly 1 db) and visual gain in 5 db steps

maybe a finer resolution also in visual gain possible instead coarse 5 db steps??

pluto has fine steps on gain AND visual gain (perfect!)

airspy hf+ has preamp on/off, att from 0-48 in 6 db stebs and visual gain in 5 db steps (-40 to +30db) ... also there a finer visual gain could be added in 1 db steps

i think if you have at least the visual gain in fine steps on all different sdr setups a good s meter calibration should be possible on all sdr

and visual gain does not depend on used hardware so change that to finer steps should be easy.. not??

maybe a number box with up down buttons instead a dropdown list?? (just thinking)

dg9bfc sigi

Am 23.11.2022 um 18:16 schrieb Simon Brown:

OK,

Some of these radios have fixed attenuation options, for example NetSDR. HF+ - I'll have to check.

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 23 November 2022 15:34
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Attenuation
 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


--

- + - + -

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

 


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


jdow
 

He was going to redo "Visual Gain" to make it a real visual gain control that simply scales the displays. As it is the last I knew the visual gain control was a literal digital gain applied to the entire system which led to some unfortunate behavior. Simon was going to doctor this last I knew. But, I may have missed his actually doing it as I do not think it's been fixed yet.


{^_^}


On 20221124 17:44:05, Siegfried Jackstien wrote:

don´t you have also "visual gain" in all sdr used?? that could be done in 1 db steps so finetune of any sdr to correct readings should be possible

if no visual gain in all sdr setups under "radio" settings ... then you could add it where that is missing

rtl for example has fine steps (but not exactly 1 db) and visual gain in 5 db steps

maybe a finer resolution also in visual gain possible instead coarse 5 db steps??

pluto has fine steps on gain AND visual gain (perfect!)

airspy hf+ has preamp on/off, att from 0-48 in 6 db stebs and visual gain in 5 db steps (-40 to +30db) ... also there a finer visual gain could be added in 1 db steps

i think if you have at least the visual gain in fine steps on all different sdr setups a good s meter calibration should be possible on all sdr

and visual gain does not depend on used hardware so change that to finer steps should be easy.. not??

maybe a number box with up down buttons instead a dropdown list?? (just thinking)

dg9bfc sigi

Am 23.11.2022 um 18:16 schrieb Simon Brown:
OK,

Some of these radios have fixed attenuation options, for example NetSDR. HF+ - I'll have to check.

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 23 November 2022 15:34
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Attenuation
 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


--

- + - + -

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

 


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


vince battle
 

Hi Sigi,

I have “visual gain” only when I use the Airspy Discovery, but the spectrum jumps up and down so much, I stopped using the Airspy for voice and only use it for “data” (FT8). Now I must confess I use remote (spyserver) for the Airspy. I do not use the Icom RS8600 with SDRC because the “scan” functions are not operational on SDRC.

My “still rocking” NetSDR does not have “visual gain “available and I have too use the “RF gain”/

 

Vincent   

 

Sent from Mail for Windows

 

From: jdow
Sent: Thursday, November 24, 2022 7:45 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

He was going to redo "Visual Gain" to make it a real visual gain control that simply scales the displays. As it is the last I knew the visual gain control was a literal digital gain applied to the entire system which led to some unfortunate behavior. Simon was going to doctor this last I knew. But, I may have missed his actually doing it as I do not think it's been fixed yet.

 

{^_^}

 

On 20221124 17:44:05, Siegfried Jackstien wrote:

don´t you have also "visual gain" in all sdr used?? that could be done in 1 db steps so finetune of any sdr to correct readings should be possible

if no visual gain in all sdr setups under "radio" settings ... then you could add it where that is missing

rtl for example has fine steps (but not exactly 1 db) and visual gain in 5 db steps

maybe a finer resolution also in visual gain possible instead coarse 5 db steps??

pluto has fine steps on gain AND visual gain (perfect!)

airspy hf+ has preamp on/off, att from 0-48 in 6 db stebs and visual gain in 5 db steps (-40 to +30db) ... also there a finer visual gain could be added in 1 db steps

i think if you have at least the visual gain in fine steps on all different sdr setups a good s meter calibration should be possible on all sdr

and visual gain does not depend on used hardware so change that to finer steps should be easy.. not??

maybe a number box with up down buttons instead a dropdown list?? (just thinking)

dg9bfc sigi

Am 23.11.2022 um 18:16 schrieb Simon Brown:

OK,

 

Some of these radios have fixed attenuation options, for example NetSDR. HF+ - I'll have to check.

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 23 November 2022 15:34
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Attenuation

 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


--

- + - + -

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

 


--

- + - + -

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

 


jdow
 

The AirSpy discovery is pretty much designed to run with its own agc active. But that is likely to be awkward for SSB reception with the usual receiver AGC active. The hope is that the time constant for the Discovery's AGC is long (for release at least) compared to that used inside the SDR software. Otherwise you get odd phenomena as you described. This is compounded when you use the Discovery as an IF for the 8600. It's not really designed for that use but you can in both cases switch over to manual gain.

Setting up manual gain is not trivial. Maybe somebody who knows noise figure work and has a Discovery in MGC mode can describe their configuration.

{^_^}

On 20221125 17:03:44, vince battle wrote:

Hi Sigi,

I have “visual gain” only when I use the Airspy Discovery, but the spectrum jumps up and down so much, I stopped using the Airspy for voice and only use it for “data” (FT8). Now I must confess I use remote (spyserver) for the Airspy. I do not use the Icom RS8600 with SDRC because the “scan” functions are not operational on SDRC.

My “still rocking” NetSDR does not have “visual gain “available and I have too use the “RF gain”/

 

Vincent   

 

Sent from Mail for Windows

 

From: jdow
Sent: Thursday, November 24, 2022 7:45 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

He was going to redo "Visual Gain" to make it a real visual gain control that simply scales the displays. As it is the last I knew the visual gain control was a literal digital gain applied to the entire system which led to some unfortunate behavior. Simon was going to doctor this last I knew. But, I may have missed his actually doing it as I do not think it's been fixed yet.

 

{^_^}

 

On 20221124 17:44:05, Siegfried Jackstien wrote:

don´t you have also "visual gain" in all sdr used?? that could be done in 1 db steps so finetune of any sdr to correct readings should be possible

if no visual gain in all sdr setups under "radio" settings ... then you could add it where that is missing

rtl for example has fine steps (but not exactly 1 db) and visual gain in 5 db steps

maybe a finer resolution also in visual gain possible instead coarse 5 db steps??

pluto has fine steps on gain AND visual gain (perfect!)

airspy hf+ has preamp on/off, att from 0-48 in 6 db stebs and visual gain in 5 db steps (-40 to +30db) ... also there a finer visual gain could be added in 1 db steps

i think if you have at least the visual gain in fine steps on all different sdr setups a good s meter calibration should be possible on all sdr

and visual gain does not depend on used hardware so change that to finer steps should be easy.. not??

maybe a number box with up down buttons instead a dropdown list?? (just thinking)

dg9bfc sigi

Am 23.11.2022 um 18:16 schrieb Simon Brown:

OK,

 

Some of these radios have fixed attenuation options, for example NetSDR. HF+ - I'll have to check.

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 23 November 2022 15:34
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Attenuation

 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


--

- + - + -

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

 


--

- + - + -

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

 


vince battle
 

Joanne,

I DO NOT use the Discovery with the 8600, not sure where you got that. Ok, perhaps I didn’t ask my question correctly, I understand that Simone only supports what the hardware manufacture gives him to work with, So the question is WHY doesn’t the hardware manufactures make attenuation variable instead of fixed?

 

Sent from Mail for Windows

 

From: jdow
Sent: Friday, November 25, 2022 6:31 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

The AirSpy discovery is pretty much designed to run with its own agc active. But that is likely to be awkward for SSB reception with the usual receiver AGC active. The hope is that the time constant for the Discovery's AGC is long (for release at least) compared to that used inside the SDR software. Otherwise you get odd phenomena as you described. This is compounded when you use the Discovery as an IF for the 8600. It's not really designed for that use but you can in both cases switch over to manual gain.

Setting up manual gain is not trivial. Maybe somebody who knows noise figure work and has a Discovery in MGC mode can describe their configuration.

{^_^}

On 20221125 17:03:44, vince battle wrote:

Hi Sigi,

I have “visual gain” only when I use the Airspy Discovery, but the spectrum jumps up and down so much, I stopped using the Airspy for voice and only use it for “data” (FT8). Now I must confess I use remote (spyserver) for the Airspy. I do not use the Icom RS8600 with SDRC because the “scan” functions are not operational on SDRC.

My “still rocking” NetSDR does not have “visual gain “available and I have too use the “RF gain”/

 

Vincent   

 

Sent from Mail for Windows

 

From: jdow
Sent: Thursday, November 24, 2022 7:45 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

He was going to redo "Visual Gain" to make it a real visual gain control that simply scales the displays. As it is the last I knew the visual gain control was a literal digital gain applied to the entire system which led to some unfortunate behavior. Simon was going to doctor this last I knew. But, I may have missed his actually doing it as I do not think it's been fixed yet.

 

{^_^}

 

On 20221124 17:44:05, Siegfried Jackstien wrote:

don´t you have also "visual gain" in all sdr used?? that could be done in 1 db steps so finetune of any sdr to correct readings should be possible

if no visual gain in all sdr setups under "radio" settings ... then you could add it where that is missing

rtl for example has fine steps (but not exactly 1 db) and visual gain in 5 db steps

maybe a finer resolution also in visual gain possible instead coarse 5 db steps??

pluto has fine steps on gain AND visual gain (perfect!)

airspy hf+ has preamp on/off, att from 0-48 in 6 db stebs and visual gain in 5 db steps (-40 to +30db) ... also there a finer visual gain could be added in 1 db steps

i think if you have at least the visual gain in fine steps on all different sdr setups a good s meter calibration should be possible on all sdr

and visual gain does not depend on used hardware so change that to finer steps should be easy.. not??

maybe a number box with up down buttons instead a dropdown list?? (just thinking)

dg9bfc sigi

Am 23.11.2022 um 18:16 schrieb Simon Brown:

OK,

 

Some of these radios have fixed attenuation options, for example NetSDR. HF+ - I'll have to check.

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 23 November 2022 15:34
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Attenuation

 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


--

- + - + -

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

 


--

- + - + -

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

 

 


Kriss Kliegle KA1GJU
 

   Vince, please explain/post video of this "jumping of the spectrum up and down". I have a fleet (and growing) of Airspy Discovery's on SDRC Servers and always run mine  (on large antennas) with the AGC ON, ATT OFF, PreAmp OFF unless 17M and higher, and visual gain of about 5 or 10dB. The only time I see the spectrum jump is when my electric cattle fence has leakage. Which it is currently doing despite my efforts to locate the problem. (The thin horizontal lines at 1 second intervals on the waterfall)

73 Kriss KA1GJU


vince battle
 

Kriss,

I never recorded anything before, but I’ll give it a try

 

Sent from Mail for Windows

 

From: Kriss Kliegle KA1GJU
Sent: Saturday, November 26, 2022 9:26 AM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

   Vince, please explain/post video of this "jumping of the spectrum up and down". I have a fleet (and growing) of Airspy Discovery's on SDRC Servers and always run mine  (on large antennas) with the AGC ON, ATT OFF, PreAmp OFF unless 17M and higher, and visual gain of about 5 or 10dB. The only time I see the spectrum jump is when my electric cattle fence has leakage. Which it is currently doing despite my efforts to locate the problem. (The thin horizontal lines at 1 second intervals on the waterfall)

73 Kriss KA1GJU

Attachments:

 


vince battle
 

Kriss this is another video

 

Sent from Mail for Windows

 

From: vince battle
Sent: Saturday, November 26, 2022 11:30 AM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Kriss,

I never recorded anything before, but I’ll give it a try

 

Sent from Mail for Windows

 

From: Kriss Kliegle KA1GJU
Sent: Saturday, November 26, 2022 9:26 AM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

   Vince, please explain/post video of this "jumping of the spectrum up and down". I have a fleet (and growing) of Airspy Discovery's on SDRC Servers and always run mine  (on large antennas) with the AGC ON, ATT OFF, PreAmp OFF unless 17M and higher, and visual gain of about 5 or 10dB. The only time I see the spectrum jump is when my electric cattle fence has leakage. Which it is currently doing despite my efforts to locate the problem. (The thin horizontal lines at 1 second intervals on the waterfall)

73 Kriss KA1GJU

Attachments:

 

Attachments:

 


Kriss Kliegle KA1GJU
 

What kind of server are you running it from? I don't recognize the radio settings options vs mine.  Operating an Airspy or any SDR has the same options whether you are using one locally or via the SDRC Server (which I do 99% of the time). How does it behave when operated locally? I couldn't make out what bandwidth in the lower left tool bar, but was there a strong signal present w/in the selected bandwidth? There is a CW contest going on, but not on 17M. I used to have a contester 1/2 mile away and I was right smack in his beam path. I could hear his products on every band I listened on, WARC bands as well!

73 Kriss KA1GJU


vince battle
 

Kriss,

I’m running the Discovery remotely using the spyserver from SDRC.

I’m also running the newest SDRC version as of today.

If I operate the Discovery locally the behavior running remote is not there

The first video was 225khz and the second video was at 57khz

 

Vincent

Sent from Mail for Windows

 

From: Kriss Kliegle KA1GJU
Sent: Saturday, November 26, 2022 12:25 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

What kind of server are you running it from? I don't recognize the radio settings options vs mine.  Operating an Airspy or any SDR has the same options whether you are using one locally or via the SDRC Server (which I do 99% of the time). How does it behave when operated locally? I couldn't make out what bandwidth in the lower left tool bar, but was there a strong signal present w/in the selected bandwidth? There is a CW contest going on, but not on 17M. I used to have a contester 1/2 mile away and I was right smack in his beam path. I could hear his products on every band I listened on, WARC bands as well!

73 Kriss KA1GJU

 


Kriss Kliegle KA1GJU
 

Use Simon's SDRC Server and don't look back! hi hi
We could use more good servers (ie functioning properly, online, with decent antennas w/o massive QRM) on SDRC:
http://onairv3.sdrspace.com/onair-v3.xml

73 Kriss KA1GJU


Don Moman VE6JY
 

That link refreshes so often, and returns you to the beginning of the list so can't even begin to see who is online....

On Sat, Nov 26, 2022 at 3:49 PM Kriss Kliegle KA1GJU <kliegle@...> wrote:
Use Simon's SDRC Server and don't look back! hi hi
We could use more good servers (ie functioning properly, online, with decent antennas w/o massive QRM) on SDRC:
http://onairv3.sdrspace.com/onair-v3.xml

73 Kriss KA1GJU


vince battle
 

Kriss,

I’m not sure if your comment is a joke or helpful?

 

Sent from Mail for Windows

 

From: Kriss Kliegle KA1GJU
Sent: Saturday, November 26, 2022 2:49 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Use Simon's SDRC Server and don't look back! hi hi
We could use more good servers (ie functioning properly, online, with decent antennas w/o massive QRM) on SDRC:
http://onairv3.sdrspace.com/onair-v3.xml

73 Kriss KA1GJU

 


jdow
 

That's a longish coffee table discussion and some digging into how semiconductors really work. I do not know if I can do it justice. So I'll make a grand statement with a very brief descriptions of why.

Every variable attenuator I know for this use has very nasty downsides. This also applies to variable gain amplifier stages. For an example a diode can, for small signals, be a current variable attenuator, roughly 25 ohms at 1ma current, 12.5 at 2 ma , 50 at 0.5 ma. When the signal level becomes significant compared to the current setting the nice exponential curve, a fancy Taylor Series expansion for the nonlinearity involved) starts generating appreciable IMD. So this sort of variable attenuator is best at near zero attenuation and at maximum attenuation. At middle settings IMD will increase. Another example, a typical voltage variable gain stage for a bipolar transistor amplifier can use this same resistance effect to vary the gains. But, at mid range settings, IMD goes up. J-Fets can do moderately well, some MOSFETs can do pretty well as voltage variable resistors, especially in balanced configurations. Since the control voltage on the device is higher than for bipolars the IMD issue is mitigated maybe 20 dB. This is good enough it is sometimes seen in some analog mixer designs.

The whole picture is much more complex; but, I keep running into the same basic issues. You have to work at quite low impedance with LOTS of current in your devices to have it all work well for you with minimal IMD. "LOTS" of current is an excessive term for AirSpies. It is excessive even for RX888 MKII models.

(The real unfortunate situation is that the high attenuation attenuator and reduced gain amplifier are MORE susceptible to IMD in most conditions making the control VERY undesirable. It gets worse when you need better.)

{^_^}

On 20221126 08:58:21, vince battle wrote:

Joanne,

I DO NOT use the Discovery with the 8600, not sure where you got that. Ok, perhaps I didn’t ask my question correctly, I understand that Simone only supports what the hardware manufacture gives him to work with, So the question is WHY doesn’t the hardware manufactures make attenuation variable instead of fixed?

 

Sent from Mail for Windows

 

From: jdow
Sent: Friday, November 25, 2022 6:31 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

The AirSpy discovery is pretty much designed to run with its own agc active. But that is likely to be awkward for SSB reception with the usual receiver AGC active. The hope is that the time constant for the Discovery's AGC is long (for release at least) compared to that used inside the SDR software. Otherwise you get odd phenomena as you described. This is compounded when you use the Discovery as an IF for the 8600. It's not really designed for that use but you can in both cases switch over to manual gain.

Setting up manual gain is not trivial. Maybe somebody who knows noise figure work and has a Discovery in MGC mode can describe their configuration.

{^_^}

On 20221125 17:03:44, vince battle wrote:

Hi Sigi,

I have “visual gain” only when I use the Airspy Discovery, but the spectrum jumps up and down so much, I stopped using the Airspy for voice and only use it for “data” (FT8). Now I must confess I use remote (spyserver) for the Airspy. I do not use the Icom RS8600 with SDRC because the “scan” functions are not operational on SDRC.

My “still rocking” NetSDR does not have “visual gain “available and I have too use the “RF gain”/

 

Vincent   

 

Sent from Mail for Windows

 

From: jdow
Sent: Thursday, November 24, 2022 7:45 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

He was going to redo "Visual Gain" to make it a real visual gain control that simply scales the displays. As it is the last I knew the visual gain control was a literal digital gain applied to the entire system which led to some unfortunate behavior. Simon was going to doctor this last I knew. But, I may have missed his actually doing it as I do not think it's been fixed yet.

 

{^_^}

 

On 20221124 17:44:05, Siegfried Jackstien wrote:

don´t you have also "visual gain" in all sdr used?? that could be done in 1 db steps so finetune of any sdr to correct readings should be possible

if no visual gain in all sdr setups under "radio" settings ... then you could add it where that is missing

rtl for example has fine steps (but not exactly 1 db) and visual gain in 5 db steps

maybe a finer resolution also in visual gain possible instead coarse 5 db steps??

pluto has fine steps on gain AND visual gain (perfect!)

airspy hf+ has preamp on/off, att from 0-48 in 6 db stebs and visual gain in 5 db steps (-40 to +30db) ... also there a finer visual gain could be added in 1 db steps

i think if you have at least the visual gain in fine steps on all different sdr setups a good s meter calibration should be possible on all sdr

and visual gain does not depend on used hardware so change that to finer steps should be easy.. not??

maybe a number box with up down buttons instead a dropdown list?? (just thinking)

dg9bfc sigi

Am 23.11.2022 um 18:16 schrieb Simon Brown:

OK,

 

Some of these radios have fixed attenuation options, for example NetSDR. HF+ - I'll have to check.

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 23 November 2022 15:34
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Attenuation

 

Greetings,

NetSDR, Icom RS-6500 and Airspy Discovery

 

Vincent

 

Sent from Mail for Windows

 

From: Simon Brown
Sent: Tuesday, November 22, 2022 9:21 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Attenuation

 

Which radio?

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of vince battle via groups.io <muellertwo@...>
Sent: 22 November 2022 22:46
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: [SDR-Radio] Attenuation

 

Greetings,
I have always wondered why attenuation settings both hardware and software or in 10db increments and not variable? is this a hardware issue or software issue? Many times, 10-30db increments is too much and something between these settings is better. 

Vincent 


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

 


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

 

 


Max
 

On Sat, Nov 26, 2022 at 11:07 PM, Don Moman VE6JY wrote:
That link refreshes so often, and returns you to the beginning of the list so can't even begin to see who is online....
Agree Don the auto-refresh is annoying as it keeps returning the list back to the top every 10 seconds. Could it be disabled to let people manually refresh, or at least have a tick-box option on the web page?

Or I guess maybe as it is XML it's not intended to be viewed? Maybe it's for input to the server list in SDRC?

Max


Kriss Kliegle KA1GJU
 

If you place the scroll bar on the righthand side to where you want to view, leave it there. When screen refreshes, just click and hold and it will return back there. But you gotta read what you need real fast!
I believe it remains where you scrolled to on the iPad though.

I just use that to get an idea how my 5 servers are working and find where all the activity is. Too bad it only publishes the center frequency and bandwidth, not the actual frequency in use. hint hint nudge nudge

73 Kriss KA1GJU