Re: Trimble Geoexplorer 1,2 date problems

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.

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

--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
.

Relevant Pages

  • Re: Trimble Geoexplorer 1,2 date problems
    ... 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 ... 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. ...
    (sci.geo.satellite-nav)
  • Re: GPS week rollover due in less than 13 years
    ... potentially thousands of units that are embedded in equipment dispersed ... the GPS rollover passed by without any problems I ... There were quite a few problems associated with the last rollover. ... My concern is that these embedded GPS chipset solutions that are then ...
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  • Re: GPS week rollover due in less than 13 years
    ... the next "rollover" will occur at midnight on 6/7 April ... My question is how many current GPS implementations can be expected to ... using the leap second count ... around the world if they are liable to fail in such a short timeframe. ...
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  • Re: Date 19 years 8 months wrong
    ... if the firmware is up to date, then setting the date manually should be all ... THE GPS WEEK 1024 ROLLOVER ... receivers will handle the rollovers in stride; ...
    (sci.geo.satellite-nav)
  • Re: Date 19 years 8 months wrong
    ... The GPS signal in space has an ambiguous week ... > that's required to get the receiver working correctly. ... > THE GPS WEEK 1024 ROLLOVER ... them out, alternatively, if you can, a FULL GPS reset should ...
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