Re: Trimble Geoexplorer 1,2 date problems

Terje Mathisen wrote:
Sam Wormley wrote:
Roman Szeremeta wrote:
Their excuse for producing incorrect data is that it doesn't matter!!!

Because of the GPS Week Number Rollover, it is impossible with the current
navigation message to determine the correct date for more than 1024 weeks
(19.6 years), with out an external date source or an internal clock set by
the user... no matter who is the manufacturer.
http://www.navcen.uscg.gov/gps/geninfo/y2k/gpsweek.htm

That isn't quite true:

It is in fact trivial to check the current UTC-TAI offset and use that to determine that the 10-bit week count must have rolled over.

Yes, Terje, you are correct! Too bad the receiver manufacturers didn't
anticipate that units would be in use for a very long time.

-Sam






You can even use the known offset at the last (first) rollover to check if a second rollover must have occured.

This would allow the firmware to last for 70+ years from now.

Terje

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