[ntp:questions] Accuracy of GPS satellite signal ?

Richard Eich richard.eich at domain.invalid
Fri Jan 26 20:42:28 UTC 2007


rgilbert88 at comcast.net wrote...
> Richard Eich wrote:
> > If I were to set up five or six global locations, each time-
> > synchronized to a local GPS receiver, how much variability would I 
> > expect there to be between the time as indicated by the GPS 
> > satellites used by each local GPS receiver.
> > 
> > I'm happy to click on a link and do my own reading.  Just haven't 
> > been able to find the right link yet (still looking, though).
> > 
> > Thx
> 
> If you are using a GPS TIMING receiver with PPS output, the leading edge 
> of the PPS signal should be within about 50 nanoseconds of UTC.  How 
> accurately your computer can read that PPS signal is another story. 
> Note that is extremely important to use a receiver designed for timing 
> service; navigation receivers are optimized for navigation rather than 
> timing.

That's an important thing to know and keep in mind...thank you.

> I have experience with only one such receiver, the Motorola Oncore 
> M12+T.  I use it with a Sun Ultra 10 Workstation and Solaris 8.  I get 
> microsecond accuracy.  YMMV
> 
> It should not matter which satellites your site is using, they all keep 
> the same time to within nanoseconds!

Since we're looking for 0.500us accuracy, it sounds like we're in 
pretty good shape from the GPS sats to the GPS receiver.




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