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Transmission Bandwith though space

  1. Dec 19, 2009 #1
    I have a very little understanding of astrophysics. I wanted to know what kind of transmission bandwidth can travel through space without dissipating.
  2. jcsd
  3. Dec 20, 2009 #2
    Bandwidth gets spread out to a few Hz by the Interstellar Medium (ISM) and signals can "twinkle"/scintillate because of the random filaments of plasma that criss-cross the ISM too. Thus range is limited to ~1,000 ly or so unless the signal is very powerful and the antenna large. Arecibo, at 305 metres across, can communicate across half the Galaxy with another Arecibo if the transmission power is 100 MW - if it had a clear line of sight. But there's a lot of crud between here and there...
  4. Dec 20, 2009 #3
    Some good articles on the question of radio range...


    ...demonstrates that ETIs aren't going to be watching our TV or listening to AM/FM unless They're Here.

    http://www.setileague.org/articles/range.htm" [Broken]

    ...surprisingly short range for certain antenna assumptions.

    There's also a range calculator online...

    http://www.satsig.net/seticalc.htm" [Broken]

    ...which is fun to play with, but don't believe really BIG ranges for silly inputs.

    Realistically optimised radio beacons that say "We're Here!" can be implemented for relatively low costs over long periods, but it's a real effort to squirt lots and lots of data between the stars if you're signalling from a planet.

    There is a potentially immensely more powerful way of signalling between the stars via radio or laser, but you need to be a bit further out from the Sun.
    Last edited by a moderator: May 4, 2017
  5. Dec 20, 2009 #4
    So perhaps a larger powerful laser could do the job depending if you could relay them off satellites.

    I know other people are involved in trying to communicate. I worry that a first contact situation would be ruined because of the wrong people on this end.
  6. Dec 20, 2009 #5
    Ruined in what way?

    What I was referring to was using the Sun's gravitational focus to boost a signal. Theoretically one can communicate to other galaxies using that natural amplification effect. I suspect that will be where ETIs will put their communications systems for interstellar data-exchange.
  7. Dec 20, 2009 #6
    Well Mainly the thought of human governments making first contact. I just hope i'ts open minded scientists who have the first open diolog
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