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Discrepancy Detected In GPS Time
jones_supa writes that on Tuesday, 26th January, Aalto University's Metsähovi observatory located in Kirkkonummi, Finland, detected a rare anomaly in time reported by the GPS system (Google translation). The automatic monitoring system of a hydrogen maser atomic clock triggered an alarm which reported a deviation of 13.7 microseconds. While this is tiny, it is a sign of a problem somewhere, and does not exclude the possibility of larger timekeeping problems happening. The specific source of the problem is not known, but candidates are a faulty GPS satellite or an atomic clock placed in one. Particle flare-up from sun is unlikely, as the observatory has currently not detected unusually high activity from sun.
I think they have to be updated pretty much constantly. Their orbits aren't perfect and they have to be adjusted for relativity in their orbits.
"Some books contain the machinery required to create and sustain universes."-Tycho
"(...) reported a deviation of 13.7 microseconds. While this is tiny (...)"
Tiny ? It's huge.
If such an error occurs every hour, the total accumulated error would be more than 7 seconds. It's tiny if you look at it individually (well, not so tiny - your 2GHz CPU clock has a period of 500ps (picosseconds) - that's 0.0000005 microseconds).
The atomic clock period (based on Cs-133) is 108.78278 picosseconds. So this is very very large.
Alvie
A GPS clock comes with the time already set. Your private rubidium clock needs someone to tell it what time it is, which is probably going to be GPS-based anyway.
I just put some black electrical tape over the flashing 12:00.
I suppose it's a good thing I'm not running the system.