[LEAPSECS] Crunching Bulletin B numbers (POSIX time)

Tim Shepard shep at alum.mit.edu
Tue Feb 22 17:08:23 EST 2011

> Having a known list of leap seconds let one recover TAI time from a cold

> GPS receiver in a few seconds to a minute, rather than waiting ~20

> minutes for the almanac to download. Many systems have their internal

I thought GPS time had a constant offset from TAI of 19 seconds. So
as soon as you have a GPS solution, you can find TAI. No table of
leap seconds needed to accomplish that, as far as I know.

> clocks in TAI, but also have requirements to report time in UTC to

> users. Such a table would ensure these systems could come back online

> quickly without having to pay the 20 minute penalty. While the system

> may have already been down a little while when the swap is made, an

> extra 20 minutes can kill reliability targets for the system.

Hmm... maybe you could eliminate the need to report UTC time. Or
have it report UTC time but have a flashing "aproximate" or
"estimate" indicator next to the display which flashes for the
first 20 minutes or so until it has received a complete copy of the

-Tim Shepard
shep at alum.mit.edu

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