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WSJT-X, DAX RX Gain & AGC-T

DBC
DBC Member ✭✭
in Third-Party Software
I have WSJT-X installed and working on my 6400 M. I know how to set the DAX TX audio correctly, but I am having trouble with the RX DAX gain and the AGC-T gain interactions. I read that I should tune the radio to a quiet spot on the band and adjust the noise level to 30 on the WSJTX monitor meter. That does not make sense to me because there are two controls (DAX RX and AGC-T) interacting with each other. Which one? Can anyone assist me with the optimum RX setting?
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Answers

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    Try this

    First, set the AGC-T with a quiet spot on the band.

    Now, with FT8 signals, adjust the RX Level so that the received signals are in the correct place which is about 1/2 up the scale while decoding signals.

    That part is not really that critical on a FlexRadio thanks to the Dynamic Range the radio has. On older radios, it is more critical.

    73

  • DBC
    DBC Member ✭✭
    Thank you, Mike. I ended up landing with a DAX RX Gain = 56, and AGC-T = 11. I did not expect to turn the AGC-T that low. Seems to work.
  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭✭

    I should not interject, it is your system, but you are working on an incorrect premise. The WSJT-X meter measures a dB signal input and not noise. The level to aim for is mid-point during receive on an active FT8 band. It is not critical except that if you test it against number of decodes, you will see that circa 80dB plus will reduce decoding. Mid point should equate to a DAX RX gain level of about 35.

    AGC-T should either be set according to the instructions provided by Flex, completely out-with FT8 and best done on SSB, or else set automatically using SDC. Either way, usually the AGC-T setting is around 50 unless you have an exceptional noise environment.

    Your settings will look good from far, hence your belief that they "seem to work" but they are far from good. Try a few more experiments, especially noting the above figures. I think you will see better results. If not, nothing lost.

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