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Discussion in 'Electronic Basics' started by [email protected], Nov 2, 2006.

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  1. Guest

    Is it possible to bounce signals off the moon to other places on earth?
    (i.e. use the moon as a comm satellite)
     
  2. Phil Allison

    Phil Allison Guest

  3. Tim Auton

    Tim Auton Guest

    Yes. Radio HAMs do it to this day because, well, because that's the kind
    of thing they like to do. The US Navy developed a system in the 40s and
    50s, though abandoned the idea when artificial satellites became
    available:

    http://en.wikipedia.org/wiki/Communication_Moon_Relay


    Tim
     
  4. Sjouke Burry

    Sjouke Burry Guest

    Ham radio operators have used it for long
    distance connection.
     
  5. The US Signal Corp bounced radar signals off the moon in 1946. Other
    experiments followed. Some of the early satellites were actually passive
    reflectors, specifically intended for bouncing signals off of.

    Amateur radio operators started doing it in 1953. I seem to recall that
    it took some time before that for actual success, ie some had been
    trying for a while before there was success. Unlike the US military,
    ham transmitters were limited to 1KW input, so they had to make up
    for that limited power through other means.

    The signal is of course pretty weak by the time it returns to earth.
    You can offset that by using a stronger signal at the transmitter, and
    of course using large antennas, at the transmitter and at the receiver.

    Sam Harris was one of the relatively early hams to do moonbounce. Then,
    he got a job at Arecibo, and moved there, which I gather caused him
    to give up on the field. But, a couple of times after he moved down
    there in '64, he arranged to use the Arecibo array for moonbounce a couple
    of times. With that size of antenna, it made it really easy for others
    with relatively simple equipment (ie not the most low noise receivers, not
    the maximum transmitting power, and relatively small antennas). It
    apparently sounded like quite a crowded band, listening on the Arecibo
    array.

    One ham in Australia took it up, but there they were limited to a far
    lower power limit, the exact limit I can't remember. But he lived in
    the Outback, and had lots of room, so he used stacked Rhombic antennas
    made out of wire and surplus telephone poles. The size of the array
    made up for the lack of power. But, he couldn't direct
    the antenna, which limited the amount of time each month the antenna
    could "see" the moon. Eventually he rigged something so he could shift
    things a bit, and get more time in.

    Fifty years ago, there were big issues with the lack of low noise
    amplifiers for the receivers. Tubes were all there were, and they
    were generally noisy. And the higher you operated, the fewer selection
    of suitable tubes.

    That got better when the parametric amplifier came along, though they
    were in themselves complicated. When transistors got better, that helped
    a lot.

    There was a whole period where various schemes were introduced for
    picking those weak signals out of the noise.

    At this point in amateur radio signals, and the seems to be the main
    area that the concept is used (moonbounce had more potential before
    communcation satellites, but since they exist in large quantities,
    the need for moonbounce has diminished, and usually isn't worth
    the effort except to do it), there are apparently enough stations
    that have Big Antennas, good receivers and maximum power amplifiers
    that it allows for contact with relatively simple stations.

    Michael
     
  6. Jamie

    Jamie Guest

    yes
     
  7. steamer

    steamer Guest

    --For a good time search on "Mary Lou Jepson" who had an interesting
    idea concerning bouncing stuff off the moon, heh.
     
  8. John  Larkin

    John Larkin Guest


    Earth-Venus radar has been done, too.

    http://www.mentallandscape.com/Venus_Radar.htm

    John
     
  9. Phil Allison

    Phil Allison Guest

    "Anthony Fremont Asinine Cunthead & total Moron "



    ** It is called " moon bounce " by radio amateurs world wide and all
    normal people.

    EME is a merely a ham acronym used only by ASD fucked wankers.






    ....... Phil
     
  10. Avi Schwartz

    Avi Schwartz Guest

    isn't this what we call inappropriate?
     
  11. Phil Allison

    Phil Allison Guest

    "Avi Schwartz"


    ** Must be one of Freemont's fuckwit arse lickers.






    ....... Phil
     
  12. feebo

    feebo Guest

    don't reply to him - you defeat filters.
     
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