Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

Option to Automate the AGC-T setting



  • Alan
    Alan Member ✭✭✭✭

    Bill and All

    Looking at the Flex codec outputs available from the VITA49 meter packets, there are three:

    • 24kHz broadband slice receiver signal level
    • The signal strength of signals in the filter passband
    • Signal strength after AGC

    My ears cannot hear audio from the Flex Audio Out when the signal strength is below -40 dB. My hearing audio out level holds with either noise at -40 dB or with signal/noise at -40 dB.

    So, using the "Signal strength after AGC" codec, my app automatically adjusts AGC for -36 dB (3 dB above my hearing threshold) while tuned to noise only. This is working very well.

    Any thoughts on using "math" and the three available Flex Codec levels to calculate the noise floor from the combined noise/signal?

    Alan. WA9WUD

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Alan, when you say "my app automatically adjusts AGC for -36 dB ..." do you really mean the AGC-T?

  • Alan
    Alan Member ✭✭✭✭


    Well, you have me scratching my head. I used this guide for my auto AGC app : https://www.flexradio.com/videos/flex-6000-receiver-tuning-how-the-agc-t-works/

    API commands include:

    • Mode Command, "slice set <slice number> agc_mode=<mode>". (off, slow, med, high)
    • AGC Threshold set, "slice set <slice number> agc_threashold=<value>" ( 0-100)
    • AGC Off Level set, "slice set <slice number> agc_off_level=<value>" (0-100)

    Are we talking the same?

    Alan. WA9WUD

  • WX7Y
    WX7Y Member ✭✭✭

    Alan could you send a link to your AGC-T Flow I would like to check it out?


  • Alan
    Alan Member ✭✭✭✭

    Here is a link to a YouTube Video of my Auto AGC in action.

    You can see the changing AGC Threshold when the signal strength changes, and when I manually change the AGC threshold and you can see the auto-driving back to the set point.

    It seems to work well adapting to the signal level and the noise levels.



    Alan. WA9WUD

  • Alan
    Alan Member ✭✭✭✭

    I added a button to turn Auto AGC on/off.

    Here is another video showing the Auto AGC on/off button and how it responds to only noise.



  • John KB4DU
    John KB4DU Member ✭✭✭✭

    The auto profile save would be ok if it were user choice on or off. The auto agc might be tolerable if it were user set to on or off.

    I agree with Sergei. The current agc doesn’t work very well. The threshold for noise level is useful if carefully adjusted, but does not function properly on strong signals if adjusted for weak signals, so constant fiddling with the volume level.

  • Alan
    Alan Member ✭✭✭✭

    I continue to work on an "Auto AGC" Node-Red-based application. I am getting excellent results with virtually no background noise in any signal/noise combinations.

    I am using the Flex API Codec, Signal Strength After AGC", as the controlling input to adjust the AGC threshold.

    It works very well "dynamically," adjusting AGC Threshold to all signal/noise combinations.

    I added AGC basic controls.

    I added Auto AGC controls.

    The Slow/Medium/Fast adjusts how quickly each iteration occurs to change the AGC threshold to make "Signal Strength After AGC" match the selected set point.

    Please feel free to comment.

    Alan. WA9WUD

  • Trucker
    Trucker Member ✭✭✭

    Nice work!

  • Al_NN4ZZ
    Al_NN4ZZ Member ✭✭✭

    Hi Alan,

    Do you have any video on CW signals? It would interesting to see some video comparing it’s effects on strong, medium and weak CW signals as you move around the band.

    I’m a CW only OP but your SSB videos look good. It would be interesting to hear some more feedback from other SSB operators and some other Node Red users.

    I would still like to see this integrated in SSDR along with the AGC-T line on the panadapter. Maybe Flex has an opening in their programming team…

    73, Al / NN4ZZ

  • Alan
    Alan Member ✭✭✭✭


    CW video with CW using my latest version uploaded to YouTube.

    Alan. WA9WUD

  • Al_NN4ZZ
    Al_NN4ZZ Member ✭✭✭


    That CW video sounds good. It's hard to compare the performance of your automation to the existing manual settings that the SSDR software offers without having access to both. But it does sound good.

    I wonder if the FRS technical team has seen your video and your approach. They don't comment here as much as the used to so not sure how much they monitor these posts. But It would be interesting to hear from Steve, Eric or Tim and get their thoughts.

    Regards, Al / NN4ZZ

    al (at) nn4zz (dot) com

    6600 Win10 Pro V2004 -- SSDR V3.3.33

  • Juan TG9AJR
    Juan TG9AJR Member ✭✭

    Great and I love the idea, count my vote in.

    Juan / TG9AJR

  • K6HN
    K6HN Member ✭✭
    edited December 2022

    Nice work Alan!

    Hopefully you will share the code soon as it looks great and your video's show a promising result.

  • Alan
    Alan Member ✭✭✭✭

    I added another Auto AGC video.


    I made some improvements to the auto functions.

    SSB Phone Net, with low-level signals, S4 to S8.

    Note how the Auto AGC adjusts to the different signal levels, keeping the noise low.

    I demonstrate the algorithm by manually moving the AGC threshold up, and you can see how the app re-adjusts to match the "After AGC Level" Codec to set point by changing the AGC Threshold Level.

    We are testing more and will publish the Node-Red flow in a few days.

    Alan. WA9WUD

Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.