> Date: Tue, 07 Oct 2003 23:33:45 -0700 > Subject: The Earth's not slowing down fast enough to suit Motorola > > Motorola reports that several GPS receivers in its Oncore line will > misdisplay the date on 28 Nov 2003 at midnight UTC. For a one-second window > the receivers will mistakenly report the date as 29 Nov instead of 28 Nov. > > Here's why. Every couple of years or so for the past three decades, the > International Earth Rotation Service has announced a leap-second because the > Earth is rotating slightly more slowly than an 86400-second day would > suggest. But since 1 Jan 1999, we've had an unusually long dry spell > without any leap seconds. The GPS week number in the UTC correction > parameter is 8 bits long, which allows for 256 weeks of unambiguous time > calculation. Until now this parameter has never rolled over, but because of > the dry spell 28 Nov will be exactly 256 weeks after the most recent leap > second, and the rollover will contribute to the bug. > <http://www.motorola.com/ies/GPS/docs_pdf/notification_oncore.pdf> > > Steve Allen writes in <http://www.ucolick.org/~sla/leapsecs/onlinebib.html> > that some JDAM smart bombs and other munitions are rumored to contain these > receivers. Anyone intending to use those weapons around the magic window > might want to reschedule their bombing runs for some other time. ...
for all you NTP/GPS junkies out there... :) --bill