Loading ...
Sorry, an error occurred while loading the content.

Re: [wsjtgroup] International Space Station-Bounce on 1296 MHz

Expand Messages
  • Chris Bartram
    432MHz QSOs would of course be possible. However, don t underestimate the problems with doppler - particularly with narrowband modulation schemes. Back in
    Message 1 of 4 , May 27, 2013
    • 0 Attachment
      432MHz QSOs would of course be possible. However, don't underestimate
      the problems with doppler - particularly with narrowband modulation schemes.

      Back in 1979, John G4ANB (now in W6), and I managed to demonstrate that
      forward scattering from a much smaller object, a Soyuz launcher in a
      rapidly decaying orbit, was possible using amateur equipment. The path
      we used was between my then QTH near Oxford in south central England and
      that of Ben, SM6CKU near Gothenburg in SW Sweden, at about 1300km. Ben
      copied my SSB on 432 at the time predicted by John, G4ANB's software.
      The tests were reported in the RSGB's magazine, 'Radio Communications'.

      I was running 1kW pep to 8 yagis, and Ben his 8m dish. John's software
      was run on a big mainframe - this was a few years before PCs. We'd have
      continued with these tests, but at that time - 34 years ago - much
      orbital data was classified, and we had our access to the source
      terminated. Sadly we didn't make a complete QSO.

      The Soyuz launcher was, of course, a much smaller vehicle than the ISS,
      although it was rather closer.

      Vy 73

      Chris
      GW4DGU
      --
      Chris Bartram
    • Les Rayburn
      Andreas, Congratulations again on your success and daring to experiment with new techniques. Please pass along my praise to Jan as well. My only concern in
      Message 2 of 4 , May 28, 2013
      • 0 Attachment
        Andreas,

        Congratulations again on your success and daring to experiment with new techniques. Please pass along my praise to Jan as well.

        My only concern in reading about your triumph was that others might think that large amounts of power, ERP, specialized software, and antenna tracking would all be required to duplicate your efforts. But the more that I read your blog, the more I realized that your efforts sounded very much like similar experiments conducted on 432 MHz (70cm) with airplane scatter.

        It seems to me that FSK441 mode (WSJT) should be very well suited to communicating via a rapidly moving reflector. Be it an ionized trail of gas from a meteor, or a large metallic space station.

        One difficulty that I can foresee if the amount of time required to complete a QSO, including the required exchange of all information necessary during a single ISS pass. To accomplish this it may be necessary to modify the WSJT software in the following manner:

        A.) A shorter operational period, perhaps 15 second transmission lengths.

        B.) A modification to the general messages incorporating a grid square exchange in the initial TX message. Then a reply that also includes the grid square of the called station.

        It is my belief that FSK441 might be used as the main mode to accomplish ISS-Bounce on both 432 MHz and 1296 MHz. Antennas could be as simple as single Yagi systems or loop Yagi's, fixed at an angle of 15-20 degrees in elevation, and able to be rotated in azimuth only. Similar systems are used with great success to work amateur satellites and the ISS on a daily basis.

        If success could be achieved using single Yagi systems with minimal tracking ability, your pioneering efforts might open up
        the possibility of working a large number of grids on both bands for stations limited ERP. Exciting stuff to be sure.

        Please do keep me abreast of your experiments, and I'll do the same here. It is my hope to begin to test some of these theories on 432 MHz once I can find a suitable partner with experience in FSK441 willing to try.

        Congratulations again on your successful experiment!

        --
        --
        73,

        Les Rayburn, N1LF
        121 Mayfair Park
        Maylene, AL 35114
        EM63nf

        6M VUCC #1712
        AMSAT #38965
        Grid Bandits #222
        Southeastern VHF Society
        Central States VHF Society Life Member
        Six Club #2484

        Active on 6 Meters thru 1296, 10GHz & Light



        On 5/28/2013 2:11 AM, Andreas Imse wrote:

        Hi Les,

         

        I saw your posting concerning ISS bounce.

         

        You are right, a lot of optimization has to be done in further tests.

        As Jan and I are QRV on 1296 EME in JT65C, we are well equipped to try FSK441 as well.

        But there are still some problems on my side to adjust the frequency while transmitting.

        PowerSDR of FlexRadio doesn´t accept any CAT Commands, while MOX is on.

        To use 30 seconds periods, was chosen in respect to our experience in EME.

        In our case the agreement of periods wouldn´t have been necessary.

        The signals were loud enough to do the QSO freestyle.

         

        vy 73,

        Andreas

         

         

        Andreas Imse

        DJ5AR / EI8HH

        Hinter der Kirche 31

        55129 Mainz

        Germany

         

        +49 6136 959025

        dj5ar@...

        www.dj5ar.de

         

         



      • chiefsfan2
        Has there ever been a 432 frequency designated as a calling frequency for ISS scatter? Many of you may have read about the successful QSO between DJ5AR and
        Message 3 of 4 , May 29, 2013
        • 0 Attachment

          Has there ever been a 432 frequency designated as a calling frequency for ISS scatter?

           

          Many of you may have read about the successful QSO between DJ5AR and
          Jan, PA3FXB using the ISS as a
          passive reflector, similar to airplane scatter or EME.

          Using EME protocols and periods of 30 seconds, they completed the QSO
          using CW. This involved modifying
          satellite tracking software, and compensating for the Doppler shift. You
          can read details and hear audio files on
          DJ5AR's blog here:

          http://www.dj5ar.de/?p=878

          This is quite an accomplishment, but I instantly began to wonder if it
          couldn't also be pulled off with much simpler
          equipment using WSJT software such as FSK441 (commonly used for rapidly
          moving meteor scatter QSO's).
          Doppler shift would not be a problem, even with the quick moving ISS,
          since the software is already optimized for
          short transmission periods.

          It might be necessary to modify the standard messaging to allow for a
          complete QSO exchange to happen faster,
          or to shorten the periods to 15 seconds.

          432 MHz has already proven to be very productive for airplane scatter,
          so I also wondered if 432 might be a good
          band for this type of experimentation. Lots of satellite operators are
          already equipped to operate on 432 and to track
          the ISS in real time with their antennas.

          I'd love to hear some discussion about the possibility of this. It could
          open up a lot of potential grid squares on 432 and 1296
          simply using FSK441.

          Another problem to be solved is classifying the propagation mode in LoTW
          and other logging software. Would this be considered "airplane scatter"
          or would we have to invent a whole new name for this?

          Congratulations to both hams for this accomplishment!
          --
          --
          73,

          Les Rayburn, N1LF
          121 Mayfair Park
          Maylene , AL 35114
          EM63nf

          6M VUCC #1712
          AMSAT #38965
          Grid Bandits #222
          Southeastern VHF Society
          Central States VHF Society Life Member
          Six Club #2484

          Active on 6 Meters thru 1296, 10GHz & Light

        Your message has been successfully submitted and would be delivered to recipients shortly.