The Year 2000 and GPS Week 1024 Rollover Overview
The Year 2000 Problem:
The year 2000 (Y2K) problem or "millennium bug" stems from the fact that many hardware and software systems use a two-digit date field to represent the year. When the year changes from 1999 to 2000, these systems may recognize "00" not as the year 2000 but 1900 or as an invalid date.
GPS Week 1024 Rollover:
The NAVSTAR Global Positioning System (GPS) satellites broadcast time information as epochs of GPS weeks. The current date is expressed as the number of weeks since 12:00 AM January 6, 1980. The date field is a 10-bit binary integer, which allows for 1024 weeks (0-1023). The End Of Week (EOW) rollover occurs every 1024 weeks when the week counter rolls over from 1023 to 0000; the GPS system time will rollover on midnight 21/22 August 1999. This can cause some GPS receivers to misinterpret the date and in some cases give erroneous position information.
Definition of Year 2000 Compliance:
Arbiter Systems, Inc. defines a product as year 2000 compliant if the unit will operate correctly without interruption (according to technical specifications) before, during and after the transition from the year 1999 to the year 2000. This includes the ability to output, receive and process date information. Products that output any 2-digit year codes will change from "99" to "00" and any four digit year codes will change from "1999" to "2000". Arbiter Systems is not responsible for the compliance of other external equipment or programs used in conjunction with its products.
This definition is not a statement of warranty and may not be interpreted to expand any warranty provided with products supplied by Arbiter Systems, nor does it alter or extend the limited liability of Arbiter Systems, Inc. in any way.
Arbiter Systems' Links:
- Generic GPS Year 2000 and Week 1024 compliance letter.
- Additional Information about GPS Year 2000 compliance testing.
- Table of Arbiter products stating compliance status.
Related Links:
- Motorola - Year 2000 Readiness Status.
- US Naval Observatory - GPS Week 1024 Rollover. This is a good basic description of GPS Week 1024.
- US Coast Guard Navigation Center - GPS Week 1024 Rollover. This is a more detailed discussion of GPS Week 1024.
- The Y2K Bug and the GPS EOW Rollover. This is another more detailed discussion of GPS Week 1024.
- The Computer Information Centre - Year 2000 Date Problem. This site is not directly related to GPS systems but does have a lot of information pertaining to Year 2000.