[time-nuts] GPS 1 PPS Averaging ?

Poul-Henning Kamp phk at phk.freebsd.dk
Sun Mar 13 17:44:40 EST 2005

The trouble with averaging GPS 1PPS is that it needs to be done for
multiple of 12h periods to counter the systematic effect of reception

I found that simply recording the 1PPS timings and comparing raw
samples with 86400 seconds intervals and _then_ averaging to be
the best strategy.

Usually what I do is to make the 1PPS from the GPS be the start
signal to my HP5370B and feed the 5 or 10MHz signal to stop.

The dataset needs to be collected on a computer (via GPIB) and
any cycle shifts in the 5/10 MHz needs to be resolved before
the comparison can be done.

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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