Option to Automate the AGC-T setting

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  • Idea
  • Updated 3 months ago
  • Under Consideration
Background
The AGC-T setting needs to be adjusted differently based on the band and current conditions that affect the noise floor.   We often need to make adjustments on a regular and frequent basis.   
This idea below was spurred by a request from Bill / K7UOP asking for a FlexLib feature to provide AGC-T values.   His idea is to write an external program to  set the AGC-T value based on the noise floor.   It would set the AGC-T a specific amount based on the current noise floor. He wrote such a program for PowerSDR.   Here is a link to his idea for reference:
https://community.flexradio.com/flexradio/topics/flexlib-agc-t-values-in-dbm

Idea to Automate the AGC-T setting
My idea is to take it one step further and add an option to incorporate this into SmartSDR.  It would allow you to specify the amount above the noise floor you want and then it would automatically and dynamically keep the setting there.   Here are some notes and a mockup illustrating the changes to the GUI.

Features:
- retain ability to manually adjust the AGC-T by selecting "Manual" button.
- provide the ability to automatically and dynamically adjust the AGT-T by selecting the "Auto" button.
- Provide a slider for the auto setting to adjust from +0 dB to +25 dB.

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com


  
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Al / NN4ZZ

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Posted 5 years ago

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Al / NN4ZZ

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If you like this idea, please add your vote.........


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K1ESE

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Good idea.  Add a delay so that the AGC-T isn't chasing static bursts.

73 de K1ESE
John
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Al / NN4ZZ

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John,
Thanks, I'm sure the developers will have some good ideas for averaging the noise floor.  Maybe something like checking the level once per second and averaging the last 10 or more seconds.  

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
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Al / NN4ZZ

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If you use a directional antenna, averaging the noise floor would also account for the changes you see when rotating the antenna.   The AGC-T setting would adjust automatically....you wouldn't have to make adjustments manually like you do today. 

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
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Jim K4JAF

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All great ideas, an auto AGC-T would especially be good for new Flex Users who normally leave the RF Gain on max on their non SDR rigs.  73s Jim K4JAF
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Jim K4JAF

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Another great enhancement to the Flex and has been under consideration for several years now..  Love my Flex but improvements can make it better. 
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Ken - NM9P, Elmer

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This would be very helpful. Then I could use the center button on the FlexControl for something other than AGC-T. I am constantly adjusting it, since I am a big band & mode hopper.
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Tom

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In conjunction with this AGC-T thread....I've mentioned this before, so I'll mention it again.

I've asked for some help in noise/ringing reduction when narrow filters (100-50 hz or less) are being used for hearing very weak (cw) signals seen on the waterfall (F6300) but not seen on the panadapter.  I'm referring to the S-0 to S-1 range. The fact that I can see a signal, like a vhf beacon, on the waterfall makes me believe I should be able to narrow my filter and hear it, maybe not by much, but hear it.....am I being too optimistic? 
 
I guess my point is, I hope if/when the 'Auto-AGC-T' is implemented, it will not replace the fact that, if possible, it would sure help if FRS could reduce the noise and ringing when using the very narrow bandwidth filters.
Sorry for sounding like a 'broken record'.......that's a term for us older guys :)
Tom
  
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Bill - K7UOP

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I've noticed that adjusting AGC-T to reduce the noise, ringing in the narrow filter is reduced. So, the combination of the narrow filter and adjusting the AGC threshold to just above the noise floor improves copying weak CW signals.
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Al / NN4ZZ

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Hi Tom,
In addition to Bill's good comment on the AGC-T adjustment, there are 2 other idea requests that should also help.  Here are the links....you can add your vote of support if you agree.

Improve the APF
https://community.flexradio.com/flexradio/topics/ssdr_v1_2_apf_could_use_more_gain_it_seems_diminish...

Improve the NR (which could help some on CW also)
https://community.flexradio.com/flexradio/topics/improve_nr_noise_reduction_request_to_add_another_d...

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
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Tom

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Al,

Thanks for the links. 

Bill, yes, we've been down this road before, it does help but just not enough for weak signal work. It's kinda frustrating to see a weak vhf signal on the waterfall but not able to hear it due to noise and ringing. I keep thinking some of this can be removed digitally. I'll wait to see what v1.4 brings and we'll go from there. 

Thanks for your help, it's appreciated.

Tom
(Edited)
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Bill - K7UOP

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Tom,

There have recently been a couple of "Likes" to my request for AGC-T values in dBm in FlexLib for developers (from 3 years ago). Consequently I re-read this topic and wanted to add my comments on how I manually adjust AGC-T to reduce ringing in narrow filters.

It seems to me that as the bandwidth of the filter gets narrower, noise energy within that bandwidth starts sounding more and more like a single tone at the pitch setting. This is where the perceived  ringing comes from. So, you want to set the AGC-T to a low enough value to reduce the ringing due to noise but any added energy (the CW signal) will be heard.

I tune to a clear freq. and set the filter to the narrowest bandwidth I intend to use. I then move the AGC-T to it's highest setting (100) for max. noise and then reduce it until the "ringing" is barely present (actually, go below then back up to find the sweet spot). I then set the filter to a wider setting for easier tuning and listening. If I need the narrow bandwidth for weak signal or adjacent QRM the AGC-T is already in the ballpark.  You can hover the cursor over the AGC-T slider and use the mouse wheel to easily fine tune the setting. Since the noise is reduced, you can increase the audio level to better hear that weak signal.  BTW - I always have AGC response set to FAST for CW.

With the narrow filter you can hear deeper into the noise. By properly setting AGC-T you can take advantage of this without the fatigue of static or ringing.

Of course, as noted by others, AGC-T has to be re-adjusted when any other settings are made that effects the noise floor (different band, antenna, etc.).  It would be nice if this were automated.  I hope Flex can make it happen.

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Sergey, R5AU

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Hi Bill!
You approach absolutely equal how described AGC-T functionality , however the point is for different bandwidth will be different optimal AGC-T settings - to reach max performance with Gain/Noise/AGC reaction.
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Al / NN4ZZ

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There are two AGC Idea threads. I think both have merit and are worth consideration for your vote.

https://community.flexradio.com/flexr...
2 years old, 46 votes proposes a setting to automate the AGC. I hadn't considered this idea but as an option (still allowing me to manually set it if I like) it makes sense. I gave it a vote.

https://community.flexradio.com/flexr...
4 months old, 39 votes. I like this one a little better. It's more manual but possibly more instructional. It proposes adding a line to indicate the AGC-T level. I voted for this one also.

Kev

Hi Kevin,
Adding both the line and offering the automated option would be great. Automating the setting would likely be very effective for many of us that don't always remember to tweak the setting as conditions change, or as we rotate our beams, change bands , etc. And having the visual indicator on the screen would serve as a reminder, an aid to manually adjusting , and feedback on how well the automated option is working.

Although these requests are ranked highly and have been on the list for several years, I don't think we will get any official feedback until/unless it is part of a release. While both are a SMOP, they don't seem to be a high priority compared to the other big ticket items. Maybe in V2, or V3, or V4.

Regards, Al / NN4ZZ
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Ken - NM9P, Elmer

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I will reiterate my statement from 10 months ago...

I like the idea of an "automatic AGC" as long as I can still go back to the current method at will, OR if the slider could become a +/- adjustment to nudge the position a little above or below the nominal position to account for preference or band conditions.

So Manual AGC mode - the slider functions as it does now,

Automatic AGC mode - the slider becomes a center-detent +/- control.

And if they could implement this in conjunction with an "Active Hang AGC" that I proposed in another post, it would be heavenly!
(Edited)
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Walt - KZ1F

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There is a vid that, as I recall Lee made, where he made the comment to adjust agc-t down 3dB. This was a vid where he was using flex meter. I don't know what's magical about 3dB but, at one level it makrs sense. I believe the official users guide says adjust it down until there is a noticeable drop in the volume, which would be -3dB. Programmatically, that seems doable but the challenge would be programmatically knowing when the slice was sitting on noise vs a weak signal.
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Jay / NO5J

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Kevin

Spot on, if my memory serves.

 SDRgadgets

73, Jay - NO5J

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Dan -- KC4GO

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@Walt, At one time I had produce such a video, but it appears that FlexMeter 1.0.0.5 no longer displays AGC or NR/ANF levels even though it did when the video was made. I'm sure there has been some change in the API that has made the connection not work. The FlexMeter was written by Denley Barnette but can't find a newer version.
https://drive.google.com/file/d/0B5gpcTVs7PtoN0NYVkNYSm43eFU/view?usp=sharing
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Walt - KZ1F

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Oh...my bad. Apologies Dan for not giving credit where credit was due.
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Dan -- KC4GO

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Didn't want poor Lee saddled with any goofy thing I may have put out there :) and Lee may have put something out as well.  73's all
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Jay / NO5J

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Dan
For once, The Community search function, functions.
searching on Flexmeter 1.1.0.1, the first result is ...

https://community.flexradio.com/flexradio/topics/flexmeter-file

Half way thru that thread, Howard KY6LA posted.
I posted a copy in my

Dropbox https://www.dropbox.com/s/igsnaxr91y8...
I downloaded it and checked the version and it is indeed, Flexmeter v1.1.0.1 .

Around the same time that Howard added it to his Dropbox, I placed it on SDRgadgets at ...

http://www.sdrgadgets.com/downloads/FlexMeter-1.1.0.1.zip

Which avoids Dropbox's added promotional attempts.
 
I know I mentioned that fact here in the Community at the time, but the Community search functions seems to have failed to notice it.
My packrat tendencies pay off sometimes!

 SDRgadgets

73, Jay - NO5J

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Zack Schindler - N8FNR

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We really need this added to SSDR.