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3885Re: [wsjtgroup] JT65A decode problem

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  • Andrew O'Brien
    Aug 2 6:37 PM
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      Graeme.

      I assume that you read my guide, if not check it out at http://www.obriensweb.com/bozoguidejt65a.htm

      My JT65A HF experience is that there are not may atmospheric/ionospheric conditions that impair reception.  If the signal is at the right signal to noise level, the software will decode it.  There are three other factors that I have found that DO correlate to poor decoding....

      1. Accuracy of tuning.  Are you tuned in to the received signal, is the "tolerance" setting correct?   Choose a 600 hz tolerance at first, this should work and rule out reception tuning accuracy as the issue.

      2.  Is the "RX Noise" level set correctly?  This requires the "monitor" button to be pressed (and turned green) and your sound card and "gain" level in the SpecJT to be set so that RX Noise is around zero dB when no signal is present.

      3. Is your soundcard calibrated correctly?  Check the lower left-hand corner of the screen in the main graphical display.  Ideally both numbers should be at 1.000 or within a few hundredth of 1.000.  Last evening, I was helping a person who could not be decoded by others (he could decode "OK").  His soundcard settings were off by about .400 from each other.  Once corrected, people could decode him perfectly.

      Andy K3UK

      On 8/2/07, zl1gbb <Gbbrot@...> wrote:

      Hi
      I continue to have problems with decoding. Today, at about 0000Z I
      had a brief period of no interference. I put this down to people
      switching off their computers and satellite tv sets and going to have
      lunch. I heard some JT65A stations operating on 14076 and they decoded.
      But then the decoding stops. I can hear them, see them on the waterfall
      but no callsigns come up. What is going on? This condition continued
      for some time then the interference came back, my agc operates on the
      noise and no more signals.
      I feel I have something wrong. Just what will affect the decoding?

      Graeme zl1gbb


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