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ASTRONOMY ENTHUSIAST

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  • scottish_dxer_ken
    Some time ago, there were a couple of Perseus files shared via this group of signals made using a 40m dish in Spain. The dxer recorded Venus Express, as well
    Message 1 of 3 , Aug 11 8:16 AM
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      Some time ago, there were a couple of Perseus files shared via this group of signals made using a 40m dish in Spain. The dxer recorded Venus Express, as well as the faint signals from Voyager 1.

      My question in relation to these facinating files is this.

      What freq were the signals on??

      What freq does NASA use to retrieve signals from mars via their orbiters??

      Are signals from Mars able to be received by enthusiasts with much less than the 40m dish that was used a couple of years ago?? ie with more modest equipment!!!

      And finally, can the 40m dish for example that the dxer on here used, can it receive and decode signals from the Martian craft, or is the signal encrypted by NASA???

      A lot of questions...

      Ken

      Scotland
    • Lasse Moell
      Not sure about what of the signals they were listening on... but you can give it a try :) http://descanso.jpl.nasa.gov/DPSummary/Descanso4--Voyager_new.pdf As
      Message 2 of 3 , Aug 11 8:54 AM
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        Not sure about what of the signals they were listening on... but you can
        give it a try :)
        http://descanso.jpl.nasa.gov/DPSummary/Descanso4--Voyager_new.pdf

        As for Mars, I bet the level is low and you need something quite big to
        copy, and of course the protocol is likely to be coded in a non standrad
        way, but not sure if encrypted. Seems they (NASA) even uses a relay to
        copy signals.
        http://www.redorbit.com/news/space/1112668665/mars-science-laboratory-csiro-080212/

        I really have to get my perseus converter-project going... (i.e.
        Perverter :D )
        /Lasse SM5GLC

        scottish_dxer_ken skrev 2012-08-11 17:16:
        >
        > Some time ago, there were a couple of Perseus files shared via this
        > group of signals made using a 40m dish in Spain. The dxer recorded
        > Venus Express, as well as the faint signals from Voyager 1.
        >
        > My question in relation to these facinating files is this.
        >
        > What freq were the signals on??
        >
        > What freq does NASA use to retrieve signals from mars via their
        > orbiters??
        >
        > Are signals from Mars able to be received by enthusiasts with much
        > less than the 40m dish that was used a couple of years ago?? ie with
        > more modest equipment!!!
        >
        > And finally, can the 40m dish for example that the dxer on here used,
        > can it receive and decode signals from the Martian craft, or is the
        > signal encrypted by NASA???
        >
        > A lot of questions...
        >
        > Ken
        >
        > Scotland
        >
        >
      • monitor
        Hi, In rough terms, the incoming signal level from mars is around -180 to -195 dbm and requires big, precise, cooled antennas and amplifiers.......virtually
        Message 3 of 3 , Aug 11 11:51 PM
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          Hi,

          In rough terms, the incoming signal level from mars is around -180 to
          -195 dbm and requires big, precise, cooled antennas and
          amplifiers.......virtually all of the signals will be digitally
          modulated and not immediately decipherable by hobbyists, even if one
          gets past the antenna consideration. The modulation scheme is complex
          and optimized to operate at and below the noise levels of the
          telecommunications systems.

          Bands used include L, S, X, and K band--the determining criteria varies
          and I am unsure of the precise frequencies.

          In the case of the Curiosity landing, NASA used the Odyssey spacecraft,
          which is orbiting mars every two hours and provides a approximately 20
          minute window per pass, to repeat very weak signals from Curiosity prior
          to deployment of the on-board high gain antenna. If you listen
          carefully to control room audio, you'll hear reference to the "bent
          pipe" telemetry......I believe that is the jargon for the
          repeated/redirected telemetry from Curiosity via Odyssey.

          It is interesting to see the process by which the rover is
          bootstrapped---it carried only entry and landing software during the
          cruise and landing portion of the filght and some simple routines to
          send basic photos immediately on landing. The entire entry and landing
          phase was automated. Once the rover is safe on the ground and checked
          out, the transition to ground operation software is done through a
          laborious process at 1-2mb/s depending on signal strength (directly
          related to error rate)......the weaker the signal, the slower the data
          rate has to be. I expect there are many software routines that can be
          swapped into place to optimize the rover for specific tasks, not to
          mention upgrades as they are developed.

          By the way, signals take about 14.5 minutes to reach or return to/from
          mars, thus a response to a command requires a 29 minute wait....the
          entire landing readout was being read-out in the control room 14.5
          minutes after the fact; that is, the rover was on the ground 14.5
          minutes before it could be confirmed.......that's part of what makes
          these landing such high anxiety items with such joy or sorrow after
          success or failure.

          Most of what I'm telling you here is available either via NASA TV or the
          web sites for various JPL/NASA projects.......you just have to sift
          through stuff at some length.

          best

          John C.
          _________________________________
          On 8/11/2012 8:54 AM, Lasse Moell wrote:
          > Not sure about what of the signals they were listening on... but you can
          > give it a try :)
          > http://descanso.jpl.nasa.gov/DPSummary/Descanso4--Voyager_new.pdf
          >
          > As for Mars, I bet the level is low and you need something quite big to
          > copy, and of course the protocol is likely to be coded in a non standrad
          > way, but not sure if encrypted. Seems they (NASA) even uses a relay to
          > copy signals.
          > http://www.redorbit.com/news/space/1112668665/mars-science-laboratory-csiro-080212/
          >
          > I really have to get my perseus converter-project going... (i.e.
          > Perverter :D )
          > /Lasse SM5GLC
          >
          > scottish_dxer_ken skrev 2012-08-11 17:16:
          >> Some time ago, there were a couple of Perseus files shared via this
          >> group of signals made using a 40m dish in Spain. The dxer recorded
          >> Venus Express, as well as the faint signals from Voyager 1.
          >>
          >> My question in relation to these facinating files is this.
          >>
          >> What freq were the signals on??
          >>
          >> What freq does NASA use to retrieve signals from mars via their
          >> orbiters??
          >>
          >> Are signals from Mars able to be received by enthusiasts with much
          >> less than the 40m dish that was used a couple of years ago?? ie with
          >> more modest equipment!!!
          >>
          >> And finally, can the 40m dish for example that the dxer on here used,
          >> can it receive and decode signals from the Martian craft, or is the
          >> signal encrypted by NASA???
          >>
          >> A lot of questions...
          >>
          >> Ken
          >>
          >> Scotland
          >>
          >>
          >
          >
          >
          >
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