[time-nuts] Hanging bridge question

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Mar 26 03:31:42 EDT 2014

In message <B92E1A45BB35480FA213DA5F32CEA2BA at pc52>, "Tom Van Baak" writes:

>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.

I would also like to add that the jitter on the 1PPS from the GPS
(aka: The hanging bridge) actually helps measurement precision
in exactly the same way systematic jitter makes life better a lot
of other places, from tape recording (bias = jitter) to machine

The best way to use the sawtooth correction is to apply it in software
after all the hardware measurements had their errors smoothed out by

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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