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Re: JT9-1 no decode on very strong signal why?

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  • John
    Hi Philip Yes, I find the same thing. JT9 was ofcourse designed for very weak signals, and mainly on HF. A typical Es signal can fluctuate from just detectable
    Message 1 of 4 , Jun 15, 2013
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      Hi Philip

      Yes, I find the same thing.

      JT9 was ofcourse designed for very weak signals, and mainly on HF.
      A typical Es signal can fluctuate from just detectable to massive,
      so a very large dynamic range is required.

      Any multipath, scattering or meteor reflection well cause doppler spread, and there can be plenty of multipath with short skip sporadicE signals.

      6M will also be more critical than HF regarding frequency stability and drift

      John
      GW4MBN


      --- In wsjtgroup@yahoogroups.com, "Philip" <G0isw@...> wrote:
      >
      > Hello all,
      >
      > I'm having great fun with JT9-1 on 50MHz, thanks again Joe.
      >
      > Today I had an unusual finding I was called by my friend Michel F1ABL who had a really strong signal +11dB and more, I could hear him clearly and see his trace perfectly, but I simply couldn't decode him although I was decoding weaker signals from other stations.
      >
      > We are both using Dimension 4 for our clocks and latest version of WSJT-X.
      >
      > By chance I reduced my 'digital gain for audio input' slider from its normal no signal 30dB level to almost nothing and then the decodes began to work.
      >
      > Does this mean that I have to do this every time there is a really strong signal? Is this normal and happens to others because the software is expecting a weak signal?
      >
      > Just trying to understand better.
      >
      > 73 de Philip G0ISW
      >
    • k0og
      I have found the same thing occasionally, and found that if I reduce the line-in fader in Windows to reduce the apparent signal strength to the software, it
      Message 2 of 4 , Jun 15, 2013
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        I have found the same thing occasionally, and found that if I reduce the line-in fader in Windows to reduce the apparent signal strength to the software, it will begin decoding.

        73,
        -Joe-

        --- In wsjtgroup@yahoogroups.com, "John" <tonquedec@...> wrote:
        >
        > Hi Philip
        >
        > Yes, I find the same thing.
        >
        > JT9 was ofcourse designed for very weak signals, and mainly on HF.
        > A typical Es signal can fluctuate from just detectable to massive,
        > so a very large dynamic range is required.
        >
        > Any multipath, scattering or meteor reflection well cause doppler spread, and there can be plenty of multipath with short skip sporadicE signals.
        >
        > 6M will also be more critical than HF regarding frequency stability and drift
        >
        > John
        > GW4MBN
        >
        >
        > --- In wsjtgroup@yahoogroups.com, "Philip" <G0isw@> wrote:
        > >
        > > Hello all,
        > >
        > > I'm having great fun with JT9-1 on 50MHz, thanks again Joe.
        > >
        > > Today I had an unusual finding I was called by my friend Michel F1ABL who had a really strong signal +11dB and more, I could hear him clearly and see his trace perfectly, but I simply couldn't decode him although I was decoding weaker signals from other stations.
        > >
        > > We are both using Dimension 4 for our clocks and latest version of WSJT-X.
        > >
        > > By chance I reduced my 'digital gain for audio input' slider from its normal no signal 30dB level to almost nothing and then the decodes began to work.
        > >
        > > Does this mean that I have to do this every time there is a really strong signal? Is this normal and happens to others because the software is expecting a weak signal?
        > >
        > > Just trying to understand better.
        > >
        > > 73 de Philip G0ISW
        > >
        >
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