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Article #9402Re: Getting timing from line cycles (was Re: Sidereal Time Clock)
From: Bill Ossmann
Date: Tue, 08 Jan 1991 18:11
Date: Tue, 08 Jan 1991 18:11
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>In article <5972@mint17.UUCP> wilner@motcid.UUCP (Corey S. Wilner) writes: >>From what I understand, using the 60Hz line as a reference for timing is not >>a good practice if you want any accuracy. I have heard that cycles can be >>longer or shorter than 1/60th of a second and some cycles can be lost completely. > >Power frequency varies a bit in the short term to suit the power companies' >convenience, but over the long term it is *extremely* accurate, referenced >to atomic clocks and very carefully kept spot-on. They even crank in the >leap seconds. Eh?? Why do leap seconds matter when all you are controlling is the (integral) number of cycles in a single second? Or do you mean that they actually slow things down a bit so that people with clocks running off the power line don't have to insert the leap second by other means? Bill Ossmann HP Imaging Systems ossmann@hp-and.an.hp.com
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arc1-ca.pugleaf.net!utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!hplabs!hpda!hpwala!hp-and!ossmannReferences:
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Path: arc1-ca.pugleaf.net!utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!hplabs!hpda!hpwala!hp-and!ossmann From: ossmann@hp-and.HP.COM (Bill Ossmann) Newsgroups: sci.electronics Subject: Re: Getting timing from line cycles (was Re: Sidereal Time Clock) Message-ID: <13650001@hp-and.HP.COM> Date: 8 Jan 91 18:11:07 GMT References: <2137@otc.otca.oz> Organization: HP Andover Division (Massachusetts) Lines: 19