Radio teletype (RTTY) is one of the coolest sounds transmitted in my opinion.
RTTY is the method of transmitting text over RF. As letters from a keyboard are typed, a different sequence of data bits are sent, and the 'noise' as it sounds like, are each letter being transmitted. It dates back to over 50 years ago, and is a much slower process of transmitting information over the air. But the great thing is, is that I'm not alone. It's heard all of the time on TV and movies. In fact, last night on The E Ring, there was a scene where a Marine took his iPod, connected a paper clip to two 'test points' and then using the button on the front, began to broadcast CW aka Morse code, from his iPod. Then, at the Pentagon, there was a radio with a spectrum analyzer, and instead of hearing this CW, they hear RTTY which is NOT CW. Now, the assumption is made that they are receiving this signal from a base near the Marine, but it's still RTTY to the Pentagon. C'mon, seriously, they're not gonna broadcast that crap over RTTY unencrypted RF. But the real point is, that they as TV / Movie producers (more to the point) the audio guys, dig the sound of RTTY. It's just a fact that it's a lot cooler than most other RF sounds, cause it sounds 'tech'.
[Updated 12:00 anti-meridian 23 October 2005]
If you in fact would like to hear it, check it out here or here
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