GPS system clocks rolled over to week 0 on 22 August 1999 and began a new 1024-week cycle. The GPS receivers produced by DSNP, a subsidiary of Thomson-CSF Detexis, came through this critical transition without a glitch.
The engineering teams at DSNP have been looking into this date problem for many years and were ready well in advance of the event. As early as 1993, the algorithms of signal processing software and related programs were modified to tackle the discontinuity due to the switch to 0. Since July 1998, GPS constellation simulators have been used to conduct systematic rollover and re-initialization tests on GPS equipment and associated software.
In parallel, a customer information process was implemented (mailing to users, web page) to explain the phenomenon and keep them informed of progress on the tests. Compatible software versions of products affected by the phenomenon were also made available and a hotline was staffed overnight from Saturday 21 to Sunday 22 August, yet no incidents were reported.
More information: DSNP Sophie Roussel