FlexLib AGC-T values in dBm

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  • Idea
  • Updated 5 years ago
  • Under Consideration
  • (Edited)

Some time ago I wrote a program for PowerSDR CAT to automatically set AGC-T just above the noise floor. In PowerSDR the AGC-T value seemed to be related to dBm. For example if noise floor = -106 dBm, I would set AGC-T to 96 (i.e. = abs(-106) - 10). Where 10 dB above the noise floor (adjustable) gives some quieting but you can still hear the weak signals.

Right now in SmartSDR, slider adjustable values are standardized to 0-100. Would it be possible to add a Slices.AGCThresholdDB property to FlexLib, i.e. set and get dB values related to signal level in dBm ?

Setting AGC-T to the correct value, quieting noise, really enhances copy of signals right around the noise floor. AGC Threshold is much better, in this regard, than AGC Gain in other radios.

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Bill - K7UOP

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Posted 5 years ago

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Photo of Jon - KF2E

Jon - KF2E

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Bill,

If you get this working I would love to have a copy. I seem to spend a lot of time fiddling with the AGC-T.

Jon...kf2e
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Al / NN4ZZ

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Bill,
Sounds interesting.....does that imply that SSDR could also provide a control to automatically set the AGC-T value for the active slice?  

I just mocked up something to illustrate the idea.  

Features:
- retain ability to manually adjust the AGC-T
- provide the ability to automatically and dynamically adjust the AGT-T by selecting the AUTO button
- Provide a slider for the auto setting.   In the mockup I allowed for +0 dBm to +10 dBM but don't know if this is a reasonable range or not.

Seems like it could be a real neat feature if it works.   Thoughts?

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


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Joe WD5Y

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Great idea. A radio with band condition sense, in a way to put it.

73's
Joe
WD5Y
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Bill - K7UOP

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Al, Always impressed with your mockups. :)

I agree that having the Auto AGC-T built in to SmartSDR would be the best solution. But, my first effort would be to add SmardSDR support to my existing (external) program. If Flex doesn't add this feature, I might look into using their Waveform API to create an add-on program that would allow users to install this feature to the radio. But, I don't know enough yet what possibilities exist with the Waveform API. Maybe someone at Flex could comment.

Not to be picky :)  about your mockup, but.... I'd probably have the range 0-25 dB. At 25 dB the radio (my Flex5K) is just about dead quiet. But, to hear the weak signals I usually set mine to 10 dB.  Also, the unit of measure should be dB not dBm. dBm is the number of decibels relative to 1 milliwatt, which is an absolute number and used, for example, to indicate signal levels. Here, we want to set the AGC Threshold to some dB above the noise floor, whatever it may be.

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Al / NN4ZZ

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Bill,
Thanks for the feedback.  I made the adjustments to the mockup and notes.

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


***** Updated Mockup ******

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Ernest - W4EG

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I am also very impress with your mock up... Great!  I vote for this to be implemented.
(Edited)
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Al / NN4ZZ

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Bill and group,
If the idea to add the "automatic" AGC-T control to the SSDR GUI is feasible,  should it be duplicated on the "SmartSDR for Windows" category to get more input and potentially more support (votes) from others that are not be following the  Services: SmartSDR API  category?

Or is there a way to add other categories to this idea?



Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
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Bill - K7UOP

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Al, What I was asking for is a change to the FlexLib API. I didn't expect any "Likes" for the idea. Was only looking for feedback from Flex Radio programmers.

I don't see any way for me to add this topic to another Category. You may publish this idea in a separate category if you like.

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Bill - K7UOP

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Al... After looking a little more closely at the Waveform API, from what documentation and hints from comments in the code, I doubt that a 3rd party developer like me will be able to implement what you have mocked up.

The FreeDV (digital voice for ssb) example adds a new item to the list of Modes (CW, LSB, AM, etc. and now FreeDV). The actual controls (GUI) are displayed in a separate program outside of SSDR. There are no provisions to create buttons and sliders within the SSDR GUI.

To make your mockup happen Flex Radio programmers would have to add this feature to SmartSDR.  And, I "Like" that idea.  :)

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Al / NN4ZZ

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Bill, 
I added the new idea for incorporating it into SmartSDR.    Thanks for your feedback, you deserve the credit for this and I hope it is something that can be done.  We'll have to see if other users and the developers agree on the utility but it sure seems like a nice feature. 

Link to the SmartSDR version:

https://community.flexradio.com/flexradio/topics/option-to-automate-the-agc-t-setting

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

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Bill,

I would also be very interested in trying a copy. I'm constantly looking for that sweet spot which is tricky to establish for all the different conditions. I'll have to try the info you just imparted. (F6300).
Tom
W4TMW
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np2g

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WOW  I want one .