[time-nuts] Thunderbolt GPS rollover

Mark Sims holrum at hotmail.com
Thu Jun 7 20:39:23 UTC 2012


Most GPS receivers base their rollover point from their data of manufacture/firmware creation/etc.   The week rolls over 1024 weeks after that.   They tend to not be dependent upon when the actual GPS week rolls over.  Better receivers have ways of inferring the actual week after a rollover occurs...  it appears that the Thunderbolt does not do this.   Also,  most GPS receivers do not cease to work after a rollover...  they just report a bad date.

>From the Thunderbolt manual:
The first week number roll-over will occur as August 21, 1999 (GPS) transitions to August 22, 1999 (GPS). The ThunderBolt adjusts for this week rollover by adding 1024 to any week number reported by GPS which is less that week number 936 which began on December 14, 1997. With this technique, the ThunderBolt will provide an accurate translation of GPS week number and TOW to time and date until July 30, 2017. 		 	   		  


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