TOKYO — Global Positioning System (GPS) satellites will reset their week number to zero on Sunday (Aug. 22), when the GPS week number rollover (GWRO) brings Y2K-like troubles to GPS systems. Nearly 100,000 car navigation systems in Japan will remain non-compliant when GWRO arrives next week.
GPS satellites broadcast time in the form of a "week number," which counts the number of weeks that have past since Jan. 6, 1980, the first day of GPS system operations. The data, which is stored in a 10-bit format, can be counted from zero to 1,023, at which point it returns again to zero. The 1,023rd week ends on Aug. 21, 1999, so the week starting on Aug. 22 will reset or roll over back to week zero. But programs of some car navigation systems use the 1,024th week as time data, which can cause calculation errors related to satellite position and date.
Japan's Ministry of International Trade and Industry (MITI) warned earlier this week that about 95,000 units from four vendors of car navigation systems will be left non-compliant on GWRO day in Japan.
The population of products that will be affected by GWRO come from a total of about 340,000 units sold between 1992 to 1996, though many of them have already been fixed or are no longer in use. Ten models from Pioneer account for about 270,000 of the total units, seven models from Xanavi Informatics — including one that was OEMed to Hitachi — account for about 64,000 of the total units, and two models from Alpine account for about 3,000 units.
The total includes old models, and MITI estimated that about 260,000 units out of the total 340,000 are currently in use. Pioneer has been upgrading some of its models since Feb. 1998 by replacing a microcontroller with a revised program. The company has already fixed 147,000 units, and estimates that 55,000 units are in use but not fixed. Xanavi is distributing a CD-ROM to reinstall a new program into the flash memory of its systems, and estimate about 40,000 units remain unfixed. Alpine is also furnishing new microcontrollers and estimates that about 100 units are not yet fixed.
About 60 percent of the 170,000 units that remain in use and haven't been fixed are subject to the effects of the GWRO.
After the GWRO, Pioneer anticipates that its non-compliant products will freeze after switched on or will take several minutes to display a position. Xanavi's products will take time to get GPS data because satellites are not at positions calculated based on erroneous date.
These manufacturers will stand by for potential troubles on the GWRO day. Spokesmen for both Pioneer and Xanavi said the GWRO will not present a direct danger to users of their systems.
Japanese suppliers only began to export car navigation systems in last two years, and overseas models are all GWRO compliant.
