Forgot your password?
typodupeerror
Space Mars Science

Amateur Records the "Sound" of Mars Express 52

Posted by kdawson
from the music-of-the-artificial-irregular-shapes dept.
gyrogeerloose writes "A French amateur radio operator who built his own ground station using equipment from an abandoned telecom uplink site has listened in on the ESA's Mars Express space probe. While his antenna is too small to allow him to download actual data, he was able to record and convert the signal of the probe's X-Band transmitter into an audio file."
This discussion has been archived. No new comments can be posted.

Amateur Records the "Sound" of Mars Express

Comments Filter:
  • Neat, but the audio file really wasn't worth attempting to listen to. I wonder what data would actually have been transmitted in that bit of sound? Where it came from is kind of awesome though.
  • Sounds like a dead carrier, with the expected doppler shifts. The carrier is certainly strong enough to get data off from it if there were any. Probably just his bad luck that it wasn't actually uplinking any data during his short window of opportunity to record it.

    I'd imagine a lot of that window was simply reliant on getting the aim for the antenna right and holding it on target. He was using a star tracker I assume?

    • Whether the carrier is strong enough depends on the bandwidth of the signal. The downlink apparently (Google is being stubborn) uses phase shift keying at a selectable data rate from a few bps to a couple hundred kpbs, depending on conditions.
      So you'd have to have a suitable demodulator to get the data, and the big message given by the fine article is that you'd need a much bigger dish to get enough S/N to have anything to demodulate.
      I work on radio telescopes, not deep space monitors, so I don't know s
      • Re: (Score:2, Informative)

        by Anonymous Coward

        low rate data is BPSK modulated on a subcarrier which is then phase modulated on the main carrier with a mod index (or deviation) that is chosen to balance the power in the "data" and the power in the "carrier". Since the carrier power is used for navigation (e.g. the Phobos flyby) you don't suppress it all.

        All is revealed in documents at http://www.ccsds.org/ or http://deepspace.jpl.nasa.gov/dsndocs/810-005/

        Knock yourselves out... you'll be able to demodulate the bits, do the decoding, find the frames..

      • by v1 (525388)

        so I don't know squat about the demodulation.

        I'm the other way around, I know radio but nothing about space. For me, with signals like FM, usually if you can hear the carrier you can lock onto it and decode the modulation. That's what phase-locked-loops and tuned circuits are for. I've dealt with many cases of extremely noisy and low signal FM and still been able to get some modulation out of it when I couldn't even hear the carrier on sideband. I'm just very surprised they couldn't get any data out of

        • Noise is proportional to the square root of bandwidth. The signal-to-noise ratio determines the bandwidth of the signal that can be demodulated. So if they're transmitting a 1Mbps modulation scheme, then the bandwidth would be several tens of kHz and carrier has to be strong enough to present a reasonably noise-free signal of those tens of kHz bandwidth to the demodulator.
          On the other hand, if it's a 3bps modulation scheme, then the carrier could be nearly invisible and still have the necessary S/N to pre
  • Hire him (Score:4, Insightful)

    by acid06 (917409) on Sunday March 07, 2010 @12:29AM (#31386468)

    If this guy has so much motivation trying to do this as a hobby, ESA should step forward and hire him straight away.
    Imagine what he could do if he had access to proper equipment.

    • Re: (Score:2, Insightful)

      by arthurpaliden (939626)
      actually he will probably be charged with copyright infringment.
      • So his first motion before the court will be to change the venue to where the content was created... in Mars orbit.

    • Re: (Score:3, Interesting)

      by tftp (111690)

      If this guy has so much motivation trying to do this as a hobby, ESA should step forward and hire him straight away.

      There are many hams who build their own microwave radios for 10 or 24 GHz (and for other bands too) from parts [kuhne-electronic.de]. This guy, motivated and all, was mostly using off the shelf equipment. For example, look at these photos [ham-radio.com] of ham rigs - and note that those are mobile setups because the rules of the contest encourage roving.

  • Wait (Score:3, Funny)

    by JumpDrive (1437895) on Sunday March 07, 2010 @02:04AM (#31386928)
    Is he sure that was MARS Express and not his next door neighbors high speed power drill?

    Are we sure he did an off axis test? ( I saw that in a movie once)
  • by Anonymous Coward

    This 'sound' claim gets today's WTF Award for its massive HUH? factor. Seriously? This typical shortwave radio noise is worth publishing?

  • They'll often spend enormous sums of money and huge amounts of time trying to do something. Many try to communicate around the world on five watts (DXers) or try to bounce their signal off the moon (EME).

    The difference, however, is that usually the amateur radio types also happen to have instruments that can provide some measure of success. The also tend to do things that are far cooler than having a vacuum tube amplifier.

    But maybe I'm biased... I'm an amateur radio operator, after all.

    That said, I think ha

    • by thephydes (727739)
      Yes. We are often misunderstood as a bunch of weirdo's who talk in code or persist with "dead" technologies such as CW. What many people do not realise is that hams have often been at the forefront of communications technology. So, am I surprised to read a story like this one - No. Am I surprised to hear the derision of slashdotters who think that communications technology started with the mac plus (replace mac plus with your favourite piece of technology) - No again. Geez guys for a bunch that are suppo
      • > What many people do not realise is that hams have often been at the forefront of communications technology.
        From the amount of surplus equipment used by radioamateurs, it seems to me that they are quite on the trailing edge of technology...
        • by TeknoHog (164938)

          From the amount of surplus equipment used by radioamateurs, it seems to me that they are quite on the trailing edge of technology...

          Well, I see open source people doing cool new things with old hardware, while shiny new machines are being wasted on MS Office at most workplaces.

  • his antenna is too small to allow him to download actual data

    That's what she said.

"If truth is beauty, how come no one has their hair done in the library?" -- Lily Tomlin

Working...