Tom Van Baak wrote:
It also has an option to sync the PPS with GPS or UTC. I thought
they were off by an integral number of seconds so I don't expect any
change. Does anybody know what's going on here?
The GPS broadcast message includes leap second and
a0 and a1 terms which are used to forward predict UTC
from GPS time, which is derived from UTC(USNO).
A0 and A1 are what you'd guess: a phase offset and a
frequency offset.
See page 157 of the GPS ICD:
<http://www.navcen.uscg.gov/gps/geninfo/ICD-GPS-200C%20with%20IRNs%2012345.pdf>
So yes, at the ns level the two 1PPS will differ since UTC
is not the same as UTC(USNO) or any other UTC(k) for
that matter. Have you measured it? I would be interested
to know what the delta is for your receiver today. You
can also dump out the a1 and a0 corrections with binary
commands on some GPS receivers.
The GPS time is steered towards UTC(USNO) to be maintained within 1 us.
The effective difference is in a few ns. I could dig up the webpage at
USNO giving the difference if needed to. (TvB already has a mail from me
on this topic)
There should be no effective difference between them.
Cheers,
Magnus
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
