I'm currently doing some experiments with electronics, and in the process I captured the signal you can find at http://jacobo.tarrio.org/fun/mystery-signal-challenge#attachments. I captured it through my sound card's microphone input, and I've amplified it in software so it's easier to "appreciate". Obviously I know what it is, but I'd like to know who among the people who happen to read this will also be able to identify it — and better yet, tell me what's in the signal.

One clue: this signal is produced by something that was invented in 1969.
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