[time-nuts] June 30 2015 leap second
hmurray at megapathdsl.net
Tue Jan 6 22:41:10 EST 2015
time at patoka.org said:
> The question is how usually GPS modules handle leap seconds ? Is it
> satelates who send UTC time to GPS module or GPS module has firmware with
> leap second information hard-coded ?
The satellites send GPS time with a low bandwidth footnote that provides the
offset to UTC and another optional footnote with the time of the next leap
I think you can see this as a 15 second jump if you watch a GPS receiver
doing a cold start. I mean really cold as in no memory at all rather than it
has battery backed memory but has been off for several months. After several
months, the RTC has probably drifted and/or the almanac is no longer helpful,
but the UTC offset probably hasn't changed. (especially for the past few
It might be fun to warm up some low cost GPS receivers just before the great
leap, power them off for several weeks around the leap, then see how they
work when starting up post leap. The question is do they remember the next
leap as well as the (old) offset.
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