[time-nuts] GPS jumps of -13.7 us?

Chris Caudle chris at chriscaudle.org
Fri Jan 29 14:29:51 UTC 2016

On Fri, January 29, 2016 1:32 am, NeT MonK wrote:
> As a side effect of those glitch in the GPS matrix, the utc_valid_flag was
> not anymore set in the stream of the primary master clock, just before my
> secondary starts to become active (loss of primary stream) which leads to
> linux server  ptp slave to readjust of +36 seconds and jump backward -36
> seconds as far as the flags was coming back.

The difference between UTC and TAI is 36 seconds.

Are you running ptpd or linuxptp on your Linux servers?
It sounds like the ptp agent running on your servers interpreted the lack
of UTC valid flag to mean that the timestamps were now in TAI, so the
server kernel applied the TAI to UTC offset to the time received via PTP.

Chris Caudle

More information about the Time-nuts_lists.febo.com mailing list