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New 'Beta' with GPS synchronisation & NMEA-decoder via soundcard

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  • wolf_dl4yhf
    Greetings all, I have just uploaded a new version (V2.76 b23) to the beta-site. For those who experiment with the GPS (NMEA) decoder: The GPS control panel
    Message 1 of 1 , May 1, 2011
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      Greetings all,

      I have just uploaded a new version (V2.76 b23) to the beta-site. For
      those who experiment with the GPS (NMEA) decoder:

      The GPS control panel now spits out some 'debugging messages' on its own
      'Debug' panel, which may be helpful to find out what's going on
      internally. Furthermore, the pps-based sample rate measurement /
      "calibrator" now respects the maximum deviation value (entered as 'ppm
      of the measured sample rate'). The hard-coded (fixed) internal value may
      have been too critical for certain soundcards.

      The triggered spectrogram function was also modified: It shows correct
      timestamps now when running in GPS-sync'd mode, and (if the GPS is
      connected as described below), it uses the very precise GPS time instead
      of the poor PC time (which jitters badly even when synchronized via
      internet).

      Details about the GPS receiver requirements, and connection
      http://www.qsl.net/dl4yhf/speclab/frqcalib.htm#gps_pps_output

      (note that this only works if the GPS receiver has a pps output, aka
      "sync pulse". It does NOT work with an ordinary GPS receiver which only
      has a serial output for the NMEA stream)

      It's interesting to see the three european time signal transmitters (60,
      75, and 77.5 kHz) side-by-side on a fast running 'triggered'
      spectrogram, synchronized by the GPS PPS signal: DCF77 begins "exactly"
      when it should (as far as the spectrogram allows), which MSF and HBG
      arrive a bit later.


      My next test needs some more modifications of the internal processing :
      It will be to measure the absolute phase of the DCF77 signal (longwave
      time signal) over several days, to see the diurnal phase shift.

      Have a nice sunday,
      73, Wolf DL4YHF .
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