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FT8 Optimal Transmission Compression Level

Juan TG9AJR
Juan TG9AJR Member ✭✭
in Community Topics

I have a 6600 and I use JTDX for FT8/FT4, what are the ideal transmission Compression Level for a good clean quality output signal ?

If I understand correctly that will be done by adjusting:

RF Power on the SmartSDR.

TX Gain on SmartSDR DAX.

PWR on the JTDX (upper right corner vertical lever).

Thanks.

Output Level.png


Comments

  • Johan SE3X
    Johan SE3X Member ✭✭✭

    Using WSJT-X, not JTDX, guess they work about the same. This is my levels, seem to be working for me. Done some 41K contacts in FT4/FT8. No complaints so far, maybe will be coming now 😁

    image.png


  • Juan TG9AJR
    Juan TG9AJR Member ✭✭

    Hello Johan and thank you, yes I guess either WSJT-X and JTDX are about the same. Trying to be a good neighbor and operator, still learning, want to get a good clean quality signal, as I seen some nasty ones. So far I had been trying to keep my TX solid indicator line right a the -10 mark followed to about maybe a -5 with the individual square (not sure which is the correct to read).

  • Al K0VM
    Al K0VM Member ✭✭✭

    As long as your level 'square' is not showing red, your signal should be clean. . In digital modes, processsing and compression is disabled.

    AL, K0VM

  • Juan TG9AJR
    Juan TG9AJR Member ✭✭

    Thanks Al, yes I always wonder the correct reading (Level) if the solid line or the individual square (to given them some names).

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator
    edited June 2022

    I have found use DIGIU mode in radio (in radio tab of WSJT-X set mode to Pkt/digi-u.). This disables any compression or TX EQ.

    set DAX TX level to 48 and power slider in WSJT-X all the way up. The TX Level indicator on radio level meter should peak right near zero and be yellow, not red. Adjust desired power out using RF power on radio.


    Dave wo2x

  • Juan TG9AJR
    Juan TG9AJR Member ✭✭

    Thanks David, yes I also use DIGIU on my 6600, JTDX PWR to the top or sometimes I'll bring it down a notch or two (-0.3 or -0.6) then my TX Gain on SmartSDR DAX to around 40-43 trying to be in yellow well before 0 more likely to around -5 in Level.

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    You should see no difference in signal purity from TX level just reaching zer and staying yellow to running it around -5 as far as FT8 tones.

    73

    Dave wo2x

  • Juan TG9AJR
    Juan TG9AJR Member ✭✭

    OK I thought there will be a difference in that range -10 to 0 as far as the output quality, thanks.

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