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GPS rollover day 8-22-99



Wonder if anyone else has info other than this about the coming rollover 
problem?

GPS Week Number Rollover Approaches
The GPS Week Number count began at approximately midnight on the evening of
05 January 1980 / morning of 06 January 1980. Since that time, the count
has been incremented by 1 each week, and broadcast as part of the GPS
message. The GPS Week Number field is modulo 1024. This means that at the
completeion of week 1023, the GPS week number will rollover to 0 on
midnight GPS Time of the evening of 21 August 1999 / morning of 22 August
1999. Note that this corresponds to 23:59:47 UTC on 21 August 1999. 

Week beginning 
at 0000 GPS Time on GPS Week Number
broadcast by satellites 
08 Aug 1999 1022 
15 Aug 1999 1023 
22 Aug 1999 0 
29 Aug 1999 1 

Once the rollover has occured, it is the responsibility of the user (i.e.,
user equipment or software) to account for the previous 1024 weeks. 

Depending upon the manufacturer of your GPS receiver, you may or may not be
effected by the GPS Week Number Rollover on 22 August 1999. Some receivers
may display inaccurate date information, some may also calculate incorrect
navigation solutions.

Contact the manufacturer of your GPS receiver to determine if you will be
effected by the GPS week number rollover. Contacts for some GPS receiver
manufacturers can be found here or here. 
For more information, see the GPS Joint Program Office Rollover pages.
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<http://www.garmin.com/faqs/1.html>

The Garmin page says our old units may require user intervention. We need
to identify the version of our units' software. If it's 3.04, we may need
new software. If it's 3.05 or higher, no problem. They have a download at
this URL.

Guess we'll just have to see.

73
John
 
"The cure of crime is not in the electric chair, but in the high chair."
...however, the electric chair works wonders with recidivism.
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