Hi Martin,
On 2016-01-27 17:49:52, Martin Burnicki wrote:
We were able to track this down today at Meinberg.
The problem was that some satellites were sending invalid UTC correction
parameters. The UTC correction parameter set not only contains current
leap second information but also coefficients (A0, A1, WNt, tot) for a
polynomial used to compensate the fractional difference between GPS time
and UTC(USNO).
Today the faulty satellites sent about 13.7 microseconds for A0, and WNt
as well as tot were both 0. So when the GPS receiver updated its UTC
correction parameters from a faulty satellite the UTC correction jumped
from close to 0 to about 13.7 microseconds, which let the UTC time step,
and when the GPS receiver received the UTC parameter set from a healthy
satellite the UTC time stepped back.
Thanks for posting this, it's great that you managed to actually record
those frames. This explanation fits the observed behaviour (steps of
around 13us all over the world) much better than a malfunction of SVN
23. Furthermore, SVN 23 had already been decommissioned prior to these
events.
Regards, Paul Boven.
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