What is the accuracy of world time and can it be improved?

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Discussion Overview

The discussion revolves around the accuracy of world time as maintained by atomic clocks and GPS systems, exploring whether current accuracy levels can be improved. Participants examine the precision of timekeeping methods and the potential limitations in disseminating time accurately over large distances.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that atomic clocks, including those used in GPS, achieve an accuracy of about 1 nanosecond per day, while others question this figure and suggest it may be slightly inaccurate.
  • One participant cites a source indicating that the USNO master clock rate does not vary by more than 0.1 nanoseconds (100 picoseconds) per day, suggesting a high level of precision.
  • Concerns are raised about the feasibility of disseminating time with such accuracy over large distances, with one participant noting that GPS time dissemination is generally accurate to around 100 nanoseconds.
  • Another participant mentions that military GPS satellites may offer greater accuracy than commercial versions, implying that government restrictions may limit the perceived potential of GPS timekeeping.
  • There is acknowledgment of the conservative estimates regarding GPS time accuracy, with some suggesting that the full potential is not utilized for most applications.

Areas of Agreement / Disagreement

Participants express differing views on the accuracy of world time and the capabilities of GPS systems, indicating that multiple competing perspectives remain without a clear consensus on the matter.

Contextual Notes

Participants reference specific accuracy figures and potential limitations but do not resolve the discrepancies in these claims or the implications of government restrictions on GPS accuracy.

wisp
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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?
 
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wisp said:
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?

http://tycho.usno.navy.mil/clocks.html

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.
 
well, it is true that the commerical gps satallites are accurate to only 100ft, but some of the units that we (military) have are a lot more accurate than that. there's a lot 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.
 
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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