Neon John <[EMAIL PROTECTED]> wrote: > I don't quite understand why they'd all run so close during the day after a > sync but drift so fast if a sync was missed.
In a typical disciplined oscillator timeclock, the predicted error goes like the square of the time since the last lock. "Next day" is probably 6 to 12 hours after the 2AM time sync. Two days later is 30 to 36 hours. 36 squared is 9 times bigger than 12 squared, so the predicted error would be 9 times bigger for the day after a night where sync was missed. Now, I cannot actually say that the Casios or any other brands actually discipline their oscillator. I know that the cheap WWVB-locked wall clocks are not disciplined - if they're running fast 2 seconds a day, then every night they just jump back two seconds. I've had $60-$100 (Pulsar, Bulova, etc.) quartz watches keep time to within a second a month without any disciplining/tweaking since they left the factory. Not all of them are that good, some run as much as a second a day too fast or too slow. A second a day is 11ppm, a second a week is 1.6ppm, a second a month is 0.4ppm. If a watch is off by just a second a month, I don't set it except a couple of times a year. If it's off by a second a day, then it gets set several times a month. Tim. _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
