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How accurate is world time?

  1. Jan 31, 2005 #1
    Atomic clocks around the world (including the GPS) agree on a time which is accurate to about 1nS per day. I think I read somewhere that the system has to be adjusted daily because of unknown errors of about 0.9nS.
    Does anyone know if this is correct?
    Can world time achieve accuracies better than this?
  2. jcsd
  3. Jan 31, 2005 #2


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    says that the USNO master clock rate does not vary by more than .1 nanoseconds (100 picoseconds) per day.

    I don't think we can disseminate time this accurately over large distances, though.

    GPS time dissemination is one of the more accurate available methods, but it's only good to somewhere around 100ns or so from what I've read. This seems a bit conservative to me though, it's equivalent to 100 ft accuracy in position.
  4. Jan 31, 2005 #3
    well, it is true that the commerical gps satallites are accurate to only 100ft, but some of the units that we (military) have are alot more accurate than that. there's alot more in those navsats then you may know about. however, the time of 100ns, it is not entirely used to it's full potentional for most uses. it seems conserative, but that's just because of the limits that are applied to it by the gov't.
  5. Feb 2, 2005 #4
    My 1nS was a little bit out.

    The feedback is very helpful:
    USNO master clock rate does not vary by more than .1 nanoseconds (100 picoseconds) per day.
    GPS time around 100ns or more.
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