[time-nuts] Leap second glitches on NTP using Z3801A

[M. Warner Losh]

In message: <fbddc0730811162002l2e83889am8ec50910d4c3df35 at mail.gmail.com>
            "Eric Garner" <garnere at gmail.com> writes:
: Ascending from Lurk Mode, I have a (possibly stupid) question: according to
: 
: http://tycho.usno.navy.mil/leapsec.html
: 
: and Tony Jones's book "The Story of Atomic Time" GPS time does not
: account for leap seconds, So why does it alert you to them?

GPS's almanac contains the GPS to UTC offset (current, and future).
It is repeated every 20 minutes, which means it can take 20 minutes
for a cold startup to learn the current number of leapseconds...

Warner

: -eric
: 
: On Sun, Nov 16, 2008 at 7:21 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
: > Is anybody running ntpd with their Z3801A?
: >
: > If so, please check your log files and tell me if you see a bogus leap second
: > at the end of the past several months.  I've seen them for Aug, Sep, and Oct.
: >  I think they are coming from my Z3801A, but it might be something else.
: >
: > The GPS satellites are now announcing a leap second that will happen at the
: > end of the year.   The refclock driver passes that to ntpd and ntpd passes it
: > to the kernel and magic happens.
: >
: > I think the refclock-ntpd interface assumes the leap second will happen at
: > the end of the current month.  NIST only announces leap seconds a month ahead
: > on WWVB and ACTS.
: >
: > The Oncore refclock driver has a filter to wait until the current month to
: > pass the info to ntpd.  I'm working on something similar for the HP driver.
: >
: > --
: > These are my opinions, not necessarily my employer's.  I hate spam.
: >
: >
: >
: >
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: 
: 
: 
: -- 
: --Eric
: _________________________________________
: Eric Garner
: 
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