[TriEmbed] that recent 14usec GPS error wrt UTC

[Jon Wolfe]

Being in the middle of re-reading "a brief history of time" (I received an illustrated edition for xmas, it's awesome), I can't help but wonder, gravity waves? 

-------- Original message --------
From: Pete Soper via TriEmbed <triembed at triembed.org> 
Date: 1/28/2016  11:39 AM  (GMT-05:00) 
To: Triangle Embedded Interest Group <TriEmbed at TriEmbed.org> 
Subject: [TriEmbed] that recent 14usec GPS error wrt UTC 

Recently the time info from the GPS satellite system experienced a hiccup and its reckoning of UTC time was momentarily off by about 14 microseconds. This got a lot of people's attention, because they're of course used to this stuff being very precise and there's a lot of heavy duty dependence. Paul Boven figured this out and his explanation was put on today's time-nuts list digest:

"We were able to track this down today at Meinberg.

The problem was that some satellites were sending invalid UTC correction
parameters. The UTC correction parameter set not only contains current
leap second information but also coefficients (A0, A1, WNt, tot) for a
polynomial used to compensate the fractional difference between GPS time
and UTC(USNO).

Today the faulty satellites sent about 13.7 microseconds for A0, and WNt
as well as tot were both 0. So when the GPS receiver updated its UTC
correction parameters from a faulty satellite the UTC correction jumped
from close to 0 to about 13.7 microseconds, which let the UTC time step,
and when the GPS receiver received the UTC parameter set from a healthy
satellite the UTC time stepped back."

-Pete


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