Re: Leap Second display

Err wrote:

> Short answer per the US Naval Observatory:
> The Global Positioning System (GPS) epoch is January 6, 1980 and is
> synchronized to UTC. GPS is NOT adjusted for leap seconds.

True, but misleading in this context. The GPS system internally uses a
time standard that is based on UTC but without the leap seconds so as
leap seconds are added the GPS time and UTC time standards diverge (I
believe they're currently 13 seconds apart).

But as mentioned by jmorriss, the GPS satellites do include information
about leap seconds in the navigation data message and that allows
consumer receivers, like the eTrex, to correct for the difference
between UTC and GPS time when they display the current time.

As I recall, the last time there was a leap second different units
handled it in various ways. Some showed the leap second correctly in
real time, others ignored it until the unit was power cycled, and some
inserted the leap second at midnight *local* time rather than UTC.

.

Relevant Pages

  • Re: Extra leap seconds due to earthquake?
    ... >> On the GPS front, I think that GPS internal system time (UTC as at ... >> satellites) is now 13 seconds ahead of today's UTC, ... any news on when the next leap second will be added? ... > It is expected that Celestial Pole offsets related to the IAU1980 Nutation ...
    (sci.geo.satellite-nav)
  • Re: basic questions about the leapsecond
    ... "On the day prior to the insertion of a leap second the leap bits ... driver, ACTS telephone modem driver and WWV audio driver ... My own GPS system using the Garmin GPS18 LVC ... He asked if the Garmin GPS18LVC reported leap second information before the ...
    (comp.protocols.time.ntp)
  • Leap second checking
    ... been a few reports of some unix systems crashing because of the leap second. ... UTC TIME STEP ... A positive leap second will be introduced at the end of December 2008. ... Earth Orientation Center of IERS ...
    (comp.os.vms)
  • Re: Abolishing the "leap second" in atomic clocks means we lose sync with sun
    ... Sam Wormley wrote: ... >>>because design flaws mean GPS struggles to cope with leap seconds. ... GPS positioning is fine without UTC ...
    (sci.geo.satellite-nav)
  • Re: The UTC thread
    ... GPS and Leap Seconds, Time to Change?, ... UTC changes in increments of seconds, ... I should have said that the difference between UT1 and UTC ...
    (sci.astro.amateur)