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Communications Space Science

Operation Moon Bounce 103

linuxwrangler writes "Today marks the 50th anniversary of the first transmission of human voice via moon bounce. The voice was that of James Trexler and the technique became an important method of communication for the military that was used until the advent of the communications satellite. It is still a popular activity for ham radio operators."
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Operation Moon Bounce

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  • Packet #1. (Score:5, Funny)

    by SIGALRM ( 784769 ) * on Sunday July 25, 2004 @03:14AM (#9793196) Journal
    ... transmission of human voice via moon bounce ...

    But then there is always the problem of...
  • by harlingtoxad ( 798873 ) <> on Sunday July 25, 2004 @03:22AM (#9793212)
    Moon Bounce is the new wave of telecommunications!
  • Satellite! (Score:5, Funny)

    by chrispyman ( 710460 ) on Sunday July 25, 2004 @03:23AM (#9793219)
    Oh, so that's why we call the moon a natural satellite!
  • the technique became an important method of communication for the military that was used until the advent of the communications satellite

    Well, i believe this made the moon a communications satellite. but im just a nit-picker ;)

  • Even better (Score:5, Informative)

    by f8ejf ( 755486 ) on Sunday July 25, 2004 @03:29AM (#9793236)
    Laser EME (moonbounce) without using the moon retroreflectors! []

    73 de F8EJF
  • these [] were moon bounces?
  • by Fallen Andy ( 795676 ) on Sunday July 25, 2004 @03:54AM (#9793291)
    Amateur Radio Enthusiasts do CW (morse) communications using moonbounce, not voice. Given the path loss (c.a. 240dB) and power constraints on amateur stations voice is er.. difficult? (Michael: go look at Trexler's antenna spec!)...
    • " Amateur Radio Enthusiasts do CW (morse) communications using moonbounce, not voice."

      [ ] You know W5UN, or (if you are old enough) K1WHS
    • by sploxx ( 622853 ) on Sunday July 25, 2004 @07:46AM (#9793723)
      Well, CW *and* voice.
      I know a ham (I also have a ham license, but not the neccessary money for the equipment) who demonstrated this a few years ago and it was just amazing!

      He has a lot of equipment and some agreements with the goverment for increased output power.
      So he was able to do a few kW (5?)@2.5GHz on a 9m fully steerable dish and voice/SSB modulation if I recall correctly.
      Now, the first beautiful thing was seeing the lights fade in sync with the voice because of the high power requirements of the transmitter :)

      The response from the moon was clearly readable but noisy, this is very impressive if you calculate the minimum loss (in dB) that is just given by the geometry...
    • Amateur Radio Enthusiasts do CW (morse) communications using moonbounce, not voice. [Note for Non-Hams: SSB is "Single Sideband" (a form of voice communication) and CW is "Morse Code" (the old "di and dah.")] A few years back, I'd set up my 2m SSB/CW unit with a high gain directional antenna and listen in on EME. Most of it was, as you point out, CW, but occasionally there'd be some voice in there as well. Occasionally, you'd even hear an SSB station communicate with a CW station. I don't know why copying
      • " I don't know why copying the CW portion of a SSB/CW conversation is hard, but for me it's far more difficult than pure CW."

        It's likely you are not used listening to SSB over a longer period of time. Switching between SSB and CW on the receiving side is extremely difficult, because you need to adapt your "internal" filters from very low bandwidth to rather large bandwidth.

        I can listen to CW for hours and hours, but listening to SSB is extremely tiring and makes me want to throw away the headphones after
    • sorry but most moonbounce I watched performed was AM voice. One gentleman sucessfully sent a packetradio broadcast via EME.

      Out of the 50 EME sessions I sat in on in the past 20 years, only 2 were morse code. the last one was an ongoing experiment at doing EME at low power but long transmission times. and yes it was sucessful at doing EME at only 100 watts ERP.... data transmission only though.
      • AM? Why?

        I believe that AM requires about six times the power as SSB to make a transmission that is of equal readability (sorry, I'm not sure what the proper terms would be.) So why did you choose AM? -- seems to me that SSB would have been a lot easier, either letting you lose a lot less power, or giving you more `effective' power to get through with?

    • Actually voice over the moon with the right conditions is done all the time. Somewhere I have some recordings on the 2m band where this was done - and you can clearly make out the audio.
  • 47 GHz EME (Score:5, Interesting)

    by pingus ( 542585 ) on Sunday July 25, 2004 @04:11AM (#9793332)
    At my local ham radio club, a guy just gave a talk about how he is attempting to implement a 47 GHz EME system. Is is interesting because of the technical challenges. Only a few other people actually operate 47 GHz stations. The travelling wave tube that most use was originally used for military work, for a project called Milstar. Interesting that at the time none of the traffic was coded to their satellites because it was considered intristically safe because it would be very hard to build a station for it.

    Some operators do use voice, but have to use big time QRO (high power) stations because the path losses are so huge. Then with new DSP methods, voice communications can definetly work.
    • Re:47 GHz EME (Score:3, Informative)

      by MuguLover ( 797587 )
      Funny you should mention that. The first 47 GHz moonbounce echoes have been reported as being observed yesterday. This was done by a Russian (Sergei RW3BP) living in a block of flats in Moscow using a 2.4m offset dish and high power. He had to use DSP techniques to detect his signal.
      • Interesting, as the person who gave the talk was working closely with Sergei on this project. Also I believe he was working with a few guys in Canada, VE4MA and some others. It was likely our speaker and him who made the contact. DSP really makes a world of difference.
  • More info (Score:5, Informative)

    by john_smith_45678 ( 607592 ) on Sunday July 25, 2004 @04:20AM (#9793347) Journal
    More info on "Moon Bounce" [] []
  • Ah yes, the first cell phone in action...
  • by quelrods ( 521005 ) * < minus math_god> on Sunday July 25, 2004 @04:33AM (#9793378) Homepage
    Moon bounce isn't something that one can conjure up at will with the flip of a switch. The amateur radio stations doing moonbounce have uber high gain directional antennas and pump 1.5kw (1500 watts), maximum legal power, into them. What you get back is a signal so faint that you then use various pre-amps and notch filtering to pull the signal out of the noise. I was fairly certain moon bounce on ham bands was limited to CW (contious wave aka morse code.) (Morse code takes a very minimal amount of bandwith and thus the power is focused instead of scattered across a large portion of spectrum.) iirc when the government did moonbounce they would pump something more to the order of 500kW.
    • by MuguLover ( 797587 ) on Sunday July 25, 2004 @06:26AM (#9793580)

      You are right for the lower frequency bands, but once you start moving up above 1000 MHz then EME is possible with much more modest systems. For example on 23cms (1296 MHz) you can work CW EME with 100W and a 3m dish, if you are peering with someone like HB9Q [] or HB9BBD [] then you can use a lot less than that.

      The introduction of digital modes like JT44 and JT65 (using FFTs, correlation and strong FEC) has made a big difference and has made EME available for people with much smaller gardens and purses. Unfortunately there are a number of EME operators who insist that a digital mode somehow isn't "real" or that the contacts count for less. This is a shame and gives newcomers the wrong impression of a fine part of the hobby.

      I intend to get active soon with a marginal system for CW work but more than adequate for the more advanced data modes.

      For info about more reasonable microwave EME systems see G4CCH [] and N2UO []

    • Oh. So no chance of rural communities connecting to the net through a broadband moonbounce link then.

      Damn, so much for that patent...
  • by Anonymous Coward
    If they bounce the signal on the moon would it not be coming back reversed?

    Seriously? (no, not really ;-)

  • Although we may not think about it that much, we owe a lot to the moon for all the things we bounce off it or take whats bounced off it.

    The light reflected from the moon provides large people to be able to see with increased accuracy at night (full moons obviously esecially)

    We bounce lasers off of it as was recently discussed on /. to help prove general relativity.

    We bounce radio signals from the moon for use in communication. (although to a lesser degree of course)

    And although the future is quite fuzzy
    • The light reflected from the moon provides large people to be able to see with increased accuracy at night

      wait a minute! you are telling me that small people can see in the dark unaided????

      I knew there was a reson to not trust them!

    • Not to mention many other reasons to like the moon, here [] and here []...
  • by Lasuuco Tulkas ( 598141 ) on Sunday July 25, 2004 @05:17AM (#9793462)
    Finally! Proof that people in the 50's had handwriting as bad as my own []!
  • I read a SF book that used the moon bounce technique to store data. They had markers on the moon for navigation (just reflectors in the rock) People would use a transmitter on earth to send a burst of data to the moon and let it bounce back then retransmit it without storing it. just a loop. You could fit a certain amount of data in the lag. They used it on farther objects to get longer delays. Kind of a strange idea. Box
  • by identity0 ( 77976 ) on Sunday July 25, 2004 @05:38AM (#9793496) Journal
    I haven't finished reading through the article, but I remember reading about this in one of James Bamford's book about the NSA, "Body of Secrets" or "The Puzzle Palace". Basically, when you bounce a directional radio beam off the moon, it can't be intercepted by anyone except those near the place on Earth where the beam bounces back to. This would allow Navy ships at sea to send a message from the open ocean, to the moon, then to Washington without having the message picked up by the Russians. Pretty neat trick, actually.

    The reason this was in Bamford's book was that the USS Liberty, the Navy eavesdropping ship that was attacked by the Israelis in 1967, had this type of system on board and it was its primary method of communicating with the NSA people in the US. Unfortunately, the system was unreliable, and the hydraulics or pnumatics controlling the directional antenna often broke, making it unusable. Partly because of this, the ship never got the message to stay away from the conflict zone and was bombed. That's how I remember it, at least.

    Maybe that's the danger of relying too much on bleeding-edge technology.

    Anyone here heard of other stories of this technology?
    • for such a message as "stay away from that location" is hardly topsecret, they could have just used normal encrypted radio links. Were they using todays .com managers to decide that?
    • when you bounce a directional radio beam off the moon, it can't be intercepted by anyone except those near the place on Earth where the beam bounces

      Except it's bullshit, because (1) the beam is hardly directional enough to aim at a location precise enough on the moon to bounce back exactly at a certain point on earth over twice the earth-moon distance (even a well collimated laser makes a big miles-wide splotch on the moon at that distance), and (2) the returning signal is mostly *scattered* back, just li
      • There is a time window when the moon could not be seen from any part of the former Soviet Union. Moonbounce communication during that time window were actually pretty secure, unless there were Russian ships around that could intercept the signal. Since these ships would have had to be equipped with high gain antennas that cannot be disguised easily, these ships were known to the US, together with their location, thus making it possible to calculate a time window during which secure transmissions were possib
    • My dad was a communications tech on board a sister ship of the Liberty (USS Gerorgetown [] ) and from what I remember him telling me about it, they had more problems with the ship than the Tresscom system, because they used were old surplus ships. He spent a lot of time off the coast of Cuba listening to the local "news". I think he thought it was pretty cool and important because he would always tell us stories about that period of time, and didn't really say much ab
    • USS Liberty (Score:3, Informative)

      by zogger ( 617870 )
      they obviously had more than one kind of radio on board. The identity and their location was known to everyone concerned, israelis, the ship itself, and other US assets out in the med and elsewhere, along with various international HAMS who were monitoring what they could of the ongoing war taking place. The attack was delibarate, and designed to pin the blame on egypt (best credible analysis, IMO) in order to garner support for more US intervention and support for the israeli side. They went so far as to s
  • by ro_coyote ( 719566 ) on Sunday July 25, 2004 @05:59AM (#9793526)
    "FIRST POST!!"
  • Is there any record of the unauthorized use of artificial satellites to bounce signals?
    • Check this one out:

    • It was widely rumoured that in the mid-to-late seventies some of the geostationary TV satellites got hijacked for various purposes. By 'widely rumoured' I mean that my ham radio boozing buddies talked about it quite a lot and several of them were broadcast technicians who used satellite up and downlinks at work. I have no first hand proof but they alleged that early geostationary satellites were simple transponders - if you pushed stuff up on the uplink frequency with the right amount of power and in the ri
    • Google for "Captain Midnight", the guy who hijacked the HBO uplink.
  • by dpbsmith ( 263124 ) on Sunday July 25, 2004 @08:23AM (#9793814) Homepage
    and in the fifties I read all about it in "The Lost City," a Rick Brant Electronic Adventure, by John Blaine. (Pseudonym of Harold Leland Goodwin). Like Tom Swift, but more up-to-date and nerdier. This is based on many-decade-old recollections, but they end up stranded on a mountain ledge in Tibet with a hand-crank generator. As I recall the book mentions that they need to crank quite hard to power the filaments in the vacuum tubes. It's Morse Code, of course, not voice. I seem to recall that the radio waves are described as being in the radar wavelength range, but it's really been a long time and I'm into very unreliable memory here.

    I wish I could remember why they need to go to Tibet to test the equipment. Probably because If They Didn't, There Wouldn't Have Been Any Story.

    Rick's father is a dignified scientist. Rick and his father are always accompanied by lovable sidekicks Zircon (?) and, um, can't remember his name exactly, it's not "Chowdah" but something like that--an Indian (not a native American, but a person from India) who speaks amusingly broken English and makes comic errors due to his entire knowledge of the Western world having been obtained from a copy of the World Almanac.

    There seems to be quite a bit more about this at this website []
    • Hey, I loved the Rick Brant books since first finding them in the 6th grade. Great adventure imagination fodder for 10 year olds ;)

      Rick's project in "Smugglers Reef" even inspired me to build an infrared nightvision system using surplus stuff from Edmunds Scientific and an old tv set for the HV power supply.

  • The challenge mentioned here [] is still open, and remains so even after all the comments about how easy it must be that were made here []
  • Though 1954 marked the first voice bouncing off the moon the first transmission bounced off the moon was in 1947.
  • The Gubberment has you all fooled!!!
    They really just bounced that first transmission off of a hollywood sound stage.....
  • by Nom du Keyboard ( 633989 ) on Sunday July 25, 2004 @04:42PM (#9796124)
    technique became an important method of communication for the military

    Okay, shut down the war until the moon rises again.

    Let's see. Stealth fighter-bombers no moon. Communication yes moon. Bomb first, and talk about it afterwards.

  • Wow. I wouldn't really consider EME very popular. Also, isn't it mainly CW.

    To all you people commenting about telecommunications via the moon, its not all that funny. Its kina (really) cool that the moon can be used as a great big satellite. It paved the way for satelites of today. Also, we amateurs regularly evaluate our stations's radiated power, so the risk of cancer is very low.

    73 de KG6OSQ

    Check out the Amateur Radio Club of Alameda's Web site at [].
  • America will soon learn what a mistake it was to invade our lands and kill our people. 37,000 have died in Iraq, and we will make your people pay ten times over! What happened on 11 September was nothing compared to what our holy warriors have planned for you, very soon!

    Death to America! Death to the invaders in Iraq, in Afghanistan, and in Palestine!

You know you've been spending too much time on the computer when your friend misdates a check, and you suggest adding a "++" to fix it.