[time-nuts] Hanging bridge question

Tom Van Baak tvb at LeapSecond.com
Tue Mar 25 23:41:53 EDT 2014

> If you are building a GPSDO, then the 1 pps out of the GPSDO should be much better than the pps out of the GPS.


That's only true for time scales less than the cross-over point. Beyond that, the 1 PPS from the GPS receiver is actually better (more accurate). That's why the LO is disciplined by GPS, not the other way around.

For example, when monitoring the performance of a cesium clock at 1 Hz, there is no need to use a GPSDO -- a sawtooth-corrected 1PPS from a GPS timing receiver is the more accurate way to measure. A GPSDO can only make the quality of the 1PPS worse for tau beyond the crossover point.


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