# When was the autocorrelation function invented? And what was the motivation for it?

I'm just very curious about the discovery process behind the autocorrelation function.

• When was it invented?
• Was it independently invented multiple times, for example?
• What was the motivation for it?
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Can't answer the first two, but autocorrelation is heavily used in electronic "signal processing", to help extract data from a noisy signal, etc. I'm guessing that the SETI folks use it a lot. –  Daniel R Hicks Jul 14 '11 at 10:36