[ntp:questions] Z3801 Leapsecond bug - Sep 30?

shoppa at trailing-edge.com shoppa at trailing-edge.com
Sun Aug 28 13:43:43 UTC 2005

 My Z3801A on the :SYSTEM:STATUS? page knows that a leapsecond is
coming up.  The "+1 leapsecond pending" shows this.  This leapsecond
was announced this summer, and according to all the announcements it's
an extra second at the end of the year, i.e. Dec 31 2005.

But if I ask further about the date and time of the leapsecond, I get:



This is the last day of September.  (I realize that not everyone may
hex GPS time like me, so I also used the undocumented command that
shows the date in year, month, day.)  I understand that while
have never been issued other than the end of the year or halfway
the year, that the protocol allows them to be at the end of March and
September as well, and that the GPS protocol may not identify the date
of the leapsecond uniuely enough.

I'm a stratum-1 NTP  server, and I guess I'll stop using the Z3801A
and go back to something that is more reliable, like WWV audio, until I
this figured out.  Maybe the Z3801A will be off by one second from
September 30 onwards, and maybe this is fixable by a "reboot" of the
Z3801A?  Would seem a shame, mine has about two years of uptime
at this point...

I suppose this could even interrupt oscillator discipline and 10MHz
output, although I hope that these are keyed entirely off the PPS and
ignore the other stuff.  Being off by 1 second would require a slew
of 10 million oscillator cycles... wow will that require a big long
change in EFC!

Is there a fix for this bug, maybe new firmware from HP?  How did the
bug happen, by announcing a leapsecond more than three months in
advance maybe?

More information about the questions mailing list