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11536Re: [wsjtgroup] Ongoing Audio Questions

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  • Dave 'Doc' Corio
    Aug 30, 2013
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      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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