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11537Re: [wsjtgroup] Ongoing Audio Questions

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  • Joe Subich, W4TV
    Aug 30, 2013
      > However, I'm not sure I've explained my issue in enough detail.

      No, you have made your issue painfully clear to all who read these
      lists.

      > It's almost always that first transmission from the other station
      > _after I have transmitted_ that is not decoded.
      >
      > What really makes it difficult to diagnose is the fact that while
      > his signal was not decoded, every other signal on the waterfall IS
      > decoded!

      I don't know that I have ever seen either of those two scenarios. I
      suspect that only K1JT or one of the other volunteers in the developers
      group know if/how the initial quick on frequency decode differs from
      the broader secondary decode.

      > I have recorded these using the WSJT-X audio recorder, and when
      > played back, the same thing happens. Other stations decode just fine,
      > but the one I'm in QSO with loses that first decode.

      I would suggest sending those wave files to K1JT or one of the team
      and let them see if they can see what might be going on. They were
      able to determine the cause of the initial decoding issue in v 1.2
      by analyzing some of my wave files.

      > This problem has been going on for months, and is not limited to
      > WSJT-X. It also happened with previous versions of WSJT as well as
      > JT65-HF.

      That it happens with JT65-HF would tend to point to a hardware issue
      (sound card or computer) and not a software as the JT65-HF decoder
      is a separate development (different code) than WSJT or WSJT-X.
      Similarly, that it also occurs with JT9 would indicate an issue in
      the audio samples, not in the software. That it does not occur with
      non JT modes does not give the hardware a pass due to the differences
      between the JT modes and typical PSK modes.

      Causes could range from improper configuration of the sound card's
      hardware (default) sample rate to high priority process in the computer
      that runs at (or close to) xx:48 and disturbs the first decoding pass
      or even noise issues in the sound card at your working frequency.

      73,

      ... Joe, W4TV


      On 8/30/2013 6:45 AM, Dave 'Doc' Corio wrote:
      > Joe, First off, I can't thank you enough for the time you're taking for
      > me. It's very enlightening and informative, and I appreciate it!
      >
      > However, I'm not sure I've explained my issue in enough detail.
      >
      > I have no problem decoding in a general sense. For example, on a busy
      > 20M JT9 band segment, if there are 12 stations all transmitting at once,
      > chances are excellent that I'll decode every one of them - even down to
      > levels of -25, sometimes even -28 dB.
      >
      > It's only when I engage a station in QSO that I see a problem. It works
      > either of two ways:
      >
      > 1. Station calls CQ
      > I answer the CQ
      > He replies to my call and he is not decoded
      >
      > or
      >
      > 2. I call CQ
      > Station responds to my CQ and is not decoded
      >
      > It's almost always that first transmission from the other station _after
      > I have transmitted_ that is not decoded.
      >
      > What really makes it difficult to diagnose is the fact that while his
      > signal was not decoded, every other signal on the waterfall IS decoded!
      >
      > While it doesn't happen every time, I would guess that it occurs around
      > 60 to 65 % of the time. It is more prevalent on the higher bands (30
      > thru 10M) and not nearly as much on the lower bands (160 thru 40M).
      >
      > I have recorded these using the WSJT-X audio recorder, and when played
      > back, the same thing happens. Other stations decode just fine, but the
      > one I'm in QSO with loses that first decode. Almost always, the rest of
      > the QSO is fine, and unless I'm working a very weak station, the rest of
      > his transmissions decode fine.
      >
      > I have to conclude, that while you may very well be right about the
      > sound card in the SignaLink being quite noisy, that it is very unlikely
      > that this would affect only one signal out of many on a waterfall - or
      > that the only one it would affect would happen to be the one I'm trying
      > to work at that moment, repeatedly.
      >
      > This problem has been going on for months, and is not limited to WSJT-X.
      > It also happened with previous versions of WSJT as well as JT65-HF.
      > However, I have had no problems with any other digital software such as
      > DXLabs, MultiPSK, MMSSTV, EasyPal, and so on. It's only JT65 and JT-9
      > that seem to have an issue.
      >
      > Tnx es 73
      > Doc
      > KB3MOW
      >
      > On 8/29/2013 11:50 PM, Joe Subich, W4TV wrote:
      >>
      >>
      >> > The SignaLink USB, at least with Windows 7 does not have a "line"
      >> > input - only "microphone".
      >>
      >> "microphone" vs. "Line" is only a matter of the USB CODEC used -
      >> one would assume the hardware designer chose the appropriate
      >> input voltage level (and internal gain settings in the CODEC)
      >> for the device being used.
      >>
      >> > The first thing I noticed was that to bring the audio level from the
      >> > SignaLink (step 7) up to 20 or 25 dB I had to turn it all the way up.
      >> > May very well be due to the fact that I turned the Windows input from
      >> > 100% down to 65%.
      >>
      >> Then increase the Windows input. In theory increasing the input on
      >> the sound card driver would make it easier to overdrive the CODEC but
      >> perhaps your device is gain limited (or the transceiver is output
      >> limited).
      >>
      >> > Does the position of the cursor in the waterfall have any bearing on
      >> > what is decoded?
      >>
      >
      >
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