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Re: [wsjtgroup] Estimate of Probability of Double Hop MS

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  • Paul Whatton
    Some of the attempts to work trans-Atlantic on 2m have been by double hop MS. So far there have been reports of signals heard but no verified completed QSO.
    Message 1 of 4 , Jul 26, 2006
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      Some of the attempts to work trans-Atlantic on 2m have been by double
      hop MS. So far there have been reports of signals heard but no verified
      completed QSO. http://www.scit.wlv.ac.uk/vhfc/prop/

      In 2002 N2PIG claimed to have completed a MS transatlantic QSO with his
      XYL: http://www.qsl.net/dk3xt/taclaim.htm But his claim was no upheld by
      the Irish Society that sdministers the award.

      Coincidentally today we had an opening from here in the south UK to EA8,
      a distance of about 2850km. This isn't much different from the shortest
      trans-Atlantic path from EI to VO of 3100km. I worked two EA8s and
      initially assumed the QSOs must have been by double hop Es on 144MHz.
      But on reflection I think they were single hop Es from here to south CT
      and then into a strong CT to EA8 coastal tropo duct. Joe CT1HZE was
      hearing the EA8s strongly on tropo and Hepburn shows very enhanced
      conditions from CT down the west African coast to EA8.

      So I can't see any reason why tropo enhanced MS might not also work and
      give distances similar to that expected from double hop MS?

      73 Paul G4DCV

      jeff millar wrote:

      I ran some numbers just for my own education...

      Estimate 10 pings per hour at 1 second per ping
      10 ping-sec / 3600 sec = .0028 probability of ping in each second
      Probability of two simultaneous meteors in a second
      .0028 x .0028 = 7.7E-6 probability double hop per secon
      = 129,600 seconds for 50% probability of double hop ping
      = 36 hour mean time between double hop pings
      10 pings to complete a contact = 1,296,000 seconds = 360 hours =
      15 days

      This is a crude calculation, because it...

      * Doesn't consider benefits of meteor showers
      * Doesn't consider that only some pings support two hops

      With computers is does look feasible to make long range, double hop
      contacts...assuming the signal strengths support two hops.

      jeff, wa1hco
    • Chris Bartram
      ... (pun intended???!!!) ... I m sure that you re right about that, Paul. It s by far the most likely mechanism, although I ve seen some interesting
      Message 2 of 4 , Jul 26, 2006
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        On Wednesday 26 July 2006 23:27, G4DCV wrote:
        > But on reflection
        (pun intended???!!!)
        >I think they were single hop Es from here to south CT
        > and then into a strong CT to EA8 coastal tropo duct. Joe CT1HZE was
        > hearing the EA8s strongly on tropo and Hepburn shows very enhanced
        > conditions from CT down the west African coast to EA8.

        I'm sure that you're right about that, Paul. It's by far the most likely
        mechanism, although I've seen some 'interesting' hypotheses in other places.

        > So I can't see any reason why tropo enhanced MS might not also work and
        > give distances similar to that expected from double hop MS?

        It does. Ask Tim, G4LOH! I've managed to be heard by one of the EA8 guys that
        way, although there was no QSO at the time because he was still learning
        WSJT.

        Incidentally, I was stuck in the car on my way to a meeting this morning. Band
        2 FM was a complete washout. Even local stations were being captured by DX.

        Vy 73

        Chris
        GW4DGU
      • Paul Whatton
        Sorry you were stuck in the car Chris. I was scheduled to go out but I took at look at LiveMUF, decided things were brewing and so changed my mind. Good
        Message 3 of 4 , Jul 27, 2006
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          Sorry you were stuck in the car Chris. I was scheduled to go out but I
          took at look at LiveMUF, decided things were brewing and so changed my
          mind. Good decision :-)

          Getting back on topic about double hop MS.

          I believe the 144MHz IARU Region 1 meteor scatter distance record and
          world record of 3101km is for a QSO between GW4CQT (IO81LP) and UW6MA
          (KN97VE) on 12 August 1977. There have been several FSK441 over the
          horizon QSOs made including the contact between Tim G4LOH and RW3PF in
          2003 at 2605km.

          http://www.ham.se/vhf/dxrecord/dxrec.htm

          Are any of these double hop? I guess it shouldn't be ruled out but in my
          mind single-hop tropo assisted would seem to be a more probable explanation.

          So Chris, when are you going to have another go at the Brendan Trophy?
          :-) My money would be on Tim G4LOH making it. He has a permanent QTH in
          the right place, a great station, is very experienced and can be in the
          shack most days.

          BTW looking at Hepburn a trans-Atlantic tropo QSO between Africa and
          Cuba might be on the cards today! http://www.dxinfocentre.com/tropo_nat.html

          73 Paul G4DCV

          Chris Bartram wrote:
          >
          > On Wednesday 26 July 2006 23:27, G4DCV wrote:
          > > But on reflection
          > (pun intended???!!!)
          > >I think they were single hop Es from here to south CT
          > > and then into a strong CT to EA8 coastal tropo duct. Joe CT1HZE was
          > > hearing the EA8s strongly on tropo and Hepburn shows very enhanced
          > > conditions from CT down the west African coast to EA8.
          >
          > I'm sure that you're right about that, Paul. It's by far the most likely
          > mechanism, although I've seen some 'interesting' hypotheses in other
          > places.
          >
          > > So I can't see any reason why tropo enhanced MS might not also work and
          > > give distances similar to that expected from double hop MS?
          >
          > It does. Ask Tim, G4LOH! I've managed to be heard by one of the EA8
          > guys that
          > way, although there was no QSO at the time because he was still learning
          > WSJT.
          >
          > Incidentally, I was stuck in the car on my way to a meeting this
          > morning. Band
          > 2 FM was a complete washout. Even local stations were being captured
          > by DX.
          >
          > Vy 73
          >
          > Chris
          > GW4DGU
          >
          >
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