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I am not very experienced with signals, but something that has occurred to me while reading on various ways we are searching for ET signals, is that it seems most people rule out a signal unless it's in a narrow band. Is there any literature about treating signals that span a broad range of frequencies? This came from thinking that perhaps instead of utilizing a narrow band to send out a message, perhaps a theoretical ET might send their messages back and forth in a single burst, where the data, instead of "progressing" by time, progresses by frequency.

Possibility or gross concept error?

Who has attempted looking signals in this manner?

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  • $\begingroup$ Where did you read that signals not in a narrow band are excluded? $\endgroup$
    – Schlusstein
    Commented Mar 12, 2017 at 16:51
  • $\begingroup$ I get the impression that SETI et al look for carrier waves, not data (because data quickly becomes unreadable at interstellar distances). From Earth, the signals that are identifiable from furthest away are radar transmissions, not radio/TV. $\endgroup$
    – Hobbes
    Commented Mar 13, 2017 at 12:29
  • $\begingroup$ @Schusstein: Quite a few places. An example: curious.astro.cornell.edu/about-us/131-observational-astronomy/… $\endgroup$
    – Nomadyn
    Commented Mar 13, 2017 at 18:53
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    $\begingroup$ The technique you're referring to is known as 'spread spectrum' and is used on Earth e.g. by the military, because it's difficult to detect that a transmission is taking place, let alone decode it. That makes it not a good candidate for SETI. $\endgroup$
    – Hobbes
    Commented Mar 13, 2017 at 20:52
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    $\begingroup$ For anyone interested, thanks to @Hobbes for pointing me towards spread spectrum, I found an article that describes what I was thinking. It points out how we generally search for signals, as well as describes some really good reasons why spread spectrum might be used by a theoretical ETI. Not for the same reasons I was thinking though (the potential to transmit a near-infinite amount of data in a fraction of a second). Article: centauri-dreams.org/?p=22025 $\endgroup$
    – Nomadyn
    Commented Mar 14, 2017 at 21:52

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