[ntp:questions] Accuracy of GPS satellite signal ?

Richard B. Gilbert rgilbert88 at comcast.net
Wed Jan 24 15:02:35 UTC 2007

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 

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!

More information about the questions mailing list