Non-GPS derived timing sources (was Re: NTp sources that work in a datacenter)

Peter Lothberg roll at
Sun Jun 1 15:13:08 UTC 2003

> I don't expect GPS to spin out of control soon..

So GPS tracks TAI and the difference is published (2 months after the

But it's simple to build a 'jamer' that makes GPS reception not work
in a limited area, same for Loran-C used in combination with GPS in
many Sonet/SDH S1 devices.

> but I did wonder how
> hard it is to find a another reliable clock source of similar quality to
> GPS to double check GPS.

Short for a lab part of TAI, I really don't knew. GPS
price/perfromance is fenomenal.

> US clocks account for 40% of the input to TAI.

In the month of April 2003;

   NIST was 4.662%
   USNO was 44.314%

   (and we where 0.501%...)


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