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Re: [dxatlas] Skimmer on VHF/UHF

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  • David Ackrill
    ... I don t know why I wrote 50km, it s actually 217km away. I think I was thinking of the much closer one at Emley Moor (GB3MLE) which is about 47km and is a
    Message 1 of 6 , Apr 29, 2008
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      g0dja wrote:

      > I'm more into VHF and UHF than HF, so I have a reasonable set up for
      > 23cm that is capable of hearing a CW beacon with the callsign GB3MHL
      > about 50km away from me.
      >

      I don't know why I wrote 50km, it's actually 217km away. I think I was
      thinking of the much closer one at Emley Moor (GB3MLE) which is about
      47km and is a collosal signal here of course. In fact, the Skimmer does
      stuggle with that one, but there's a well known fault with the PSU on
      the beacon which makes the CW note very rough.

      Anyway, decoding on GB3MHL is much better today, so conditions may be a
      bit better and the Skimmer can now decode about 99% of the time.

      Dave (G0DJA)
    • Alex, VE3NEA
      Hi Dave, The bandwidth of the input signal in the 3-kHz mode must be 3 kHz. If it is less than that, the sensitivity of the decoder drops significantly. Your
      Message 2 of 6 , Apr 29, 2008
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        Hi Dave,

        The bandwidth of the input signal in the 3-kHz mode must be 3 kHz. If it is
        less than that, the sensitivity of the decoder drops significantly. Your
        signal has only about 1500 Hz BW - at this bandwidth, CW Skimmer can decode
        only very strong signals. Please see if you can use a wider filter in your
        radio.

        73 Alex VE3NEA




        > Alex, VE3NEA wrote:
        >> Hi Dave,
        >>
        >> Please send me a short I/Q recording of the 23 cm signal.
        >>
        >> 73 Alex VE3NEA
        >>
        >
        > Hi Alex,
        >
        > The Skimmer seems to be getting the callsign and locator 99% of the time
        > now, but I've attached a sample for you anyway.
        >
        > It got the call OK the second time, but thought the call was TI3MHL and
        > occasionally gets the 3 as a 4.
        >
        > Cheers - Dave (G0DJA)
        >
      • David Ackrill
        ... Thanks for the explanation Alex, I guess that s because I was using the CW setting on my TS2000X, the width setting was 2000Hz. I will try again using
        Message 3 of 6 , Apr 29, 2008
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          Alex, VE3NEA wrote:
          > Hi Dave,
          >
          > The bandwidth of the input signal in the 3-kHz mode must be 3 kHz. If it is
          > less than that, the sensitivity of the decoder drops significantly. Your
          > signal has only about 1500 Hz BW - at this bandwidth, CW Skimmer can decode
          > only very strong signals. Please see if you can use a wider filter in your
          > radio.
          >
          > 73 Alex VE3NEA

          Thanks for the explanation Alex,

          I guess that's because I was using the 'CW' setting on my TS2000X, the
          width setting was 2000Hz.

          I will try again using USB, as that allows me to go up to 50000Hz.
          Although your point about needing a stronger signal is born out by the
          fact that the stronger signal from the beacon today was being decoded.

          I've been using the SDR-IQ on 20M with CWSkimmer today, and have got the
          aggregator running now. However, I have noticed some errors coming up
          on the aggregator DOS window.

          One says "error:cannot send spot - http://skimmer.dxwatch.com/rx.php -
          500 server closed connection without sending any data back" and the
          other says "500 cant connect to skimmer.dxwatch.com:80 (connect: Unknown
          error)" then the next time it goes through OK for quite a long time
          until the next error message comes up.

          I thought I'd mention these errors in case they mean something to the
          operation of the aggregator.

          Cheers - Dave (G0DJA)
        • David Ackrill
          ... Ooops, that s a typo of course. The maximum width, with the TS2000X in USB, is 5000Hz. Dave (G0DJA)
          Message 4 of 6 , Apr 29, 2008
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            David Ackrill wrote:

            > I will try again using USB, as that allows me to go up to 50000Hz.

            Ooops, that's a typo of course. The maximum width, with the TS2000X in
            USB, is 5000Hz.

            Dave (G0DJA)
          • David Ackrill
            Thinking ahead a little... Is there a way to use the SDR-IQ/14 as a transverter IF, but have the Skimmer log the spots on a different frequency? For instance,
            Message 5 of 6 , Apr 29, 2008
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              Thinking ahead a little...

              Is there a way to use the SDR-IQ/14 as a transverter IF, but have the
              Skimmer log the spots on a different frequency?

              For instance, in Europe the 4M band (70MHz) is becoming available in
              more countries to Amateurs but many/most commercial radios don't cover
              the band. Or, even if they do the resultant signals and receivers are
              poor. Therefore, many people use a transverter for that band.

              Similarly, on the higher microwave bands it's not uncommon to use
              transverters from bands such as 10m/2m or even 70cm.

              Dave (G0DJA)
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