[ntp:questions] Fwd: The Earth's not slowing down fast enough to suit Motorola...

Brad Knowles brad.knowles at skynet.be
Fri Oct 10 20:05:08 UTC 2003


	Thought you might appreciate the humour in this one:

>From: bmanning at karoshi.com
>Subject: The Earth's not slowing down fast enough to suit Motorola...
>To: nanog at merit.edu
>Date: Fri, 10 Oct 2003 11:15:19 -0700 (PDT)
>>  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... :)
Brad Knowles, <brad.knowles at skynet.be>

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
     -Benjamin Franklin, Historical Review of Pennsylvania.

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