Another rule of thumb is 1 second in a dozen days is almost exactly 1 PPM. And two seconds before retirement (say, age 65) is close to 1 PPB. Three seconds a century is also 1 PPB.
Related to that, next time you read a newspaper article about atomic clocks I guarantee you'll see words like "one second in 3*** million years". That's because newspapers don't use scientific notation and because: 1e-9 is close to 1 second / 30 years 1e-12 is close to 1 second / 30 thousand years 1e-15 is close to 1 second / 30 million years, etc. /tvb ----- Original Message ----- From: "Bob Camp" <li...@rtty.us> To: "'Tom Van Baak'" <t...@leapsecond.com>; "'Discussion of precise time and frequency measurement'" <time-nuts@febo.com> Sent: Friday, September 14, 2012 9:14 AM Subject: RE: [time-nuts] RE; New Wrist watch > Hi > > Seconds per 30 day month turned out to be a pretty good unit for the watch > module specs back in the dark ages. More or less divide by 2.5 (or 2.592 if > you have a calculator) and you get ppm. > > Bob > > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Tom Van Baak > Sent: Friday, September 14, 2012 8:17 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] RE; New Wrist watch > >> So, does this unit include an input for a external reference? I would >> be interested in knowing what they use for a timing reference... >> >> :) >> >> Dan > > Last I checked with Bryan, he has XO and TCXO and GPS options for the > Microset timer. > Realize that most traditional watch/clock people are content with ppm level > accuracy/stability. > > /tvb _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
