The Global Positioning System provides accurate timing information to many of our critical systems including but not limited to our nations power grid, communications, financial markets, emergency services, and industrial control to name a few. It also transmit’s the proper date and time to a receiver by supplying the receiver with the current week and the current number of seconds in the week. This allows the receiver to translate the date and time into a more typical format – day, month, year, and time of day. The field that contains the week number is a 10-bit binary numerical number. This limits the range of the week number to 0 – 1023, or 1024 total weeks.
So what’s that mean?
The GPS Week Number count began at approximately midnight on January 6, 1980. The 1024 week counter reset on August 21, 1999, the count has been increasing by 1 each week, and broadcast as part of the GPS message. The GPS Week Number field is max 1024. This means that at the completion of week 1023, the GPS week will be reset to 0 on midnight GPS Time on April 6th, 2019.
So what could happen on April 06th, 2019? UTC timing displayed and/or time tags of receiver data containing information could jump by 19.7 years, resulting in system failures of Any month/year conversion could also fail. Navigation solution should be OK since GPS time is internally self-consistent, but associated time tags could be incorrect thus corrupting navigation data at the system level and sending you in the wrong direction this failure is not limited to April 6/7 2019
Most newer receivers are likely going to be OK if ICD-200 was followed older receiver may be problematic “Trust but Verify” consult you manufacture. The next block of GPS satellites contain a 13-bit message which will make April 06th, 2019 the last GPS “Zero weeks”
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