[time-nuts] Line Frequency

Tom Van Baak tvb at LeapSecond.com
Mon Feb 10 14:29:56 EST 2014


> Let’s say you use a magnetic pickup loop.

> Ok, how about a capacitive pickup.

Bob,

Good ideas. And extracting time from 60 Hz would be revenge for all the 60/120 Hz hum we've heard from PA systems our whole lives. Turning a problem into a solution is always satisfying.

Brooke -- IIRC some watch or clock company had a patent on calibrating a wristwatch crystal against AC hum. I read it once but can't find it now. Can you hunt for it?

While you're searching you'll run across the art of using mains frequency as a forensic tool. We discussed this on the list a while ago. Quick links are:
http://www.bbc.co.uk/news/science-environment-20629671
http://en.wikipedia.org/wiki/Electrical_network_frequency_analysis
http://www.soundonsound.com/sos/jan10/articles/forensics.htm
http://forensicoutreach.com/barely-audible-the-ins-and-outs-of-hum-forensics/

Thanks,
/tvb





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