GPS Roll over week - Back to the Future

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Some GPS receivers may malfunction on or after 6 April 2019 due to the GPS rollover.

The Global Positioning System provides accurate timing information to many systems. These include not only your mobile phone and car, but systems such as the national grid, communications, Banking systems, financial markets, emergency services, and industrial control systems and services.

It also includes the ability to transmit the correct date and time to a GPS receiver by sending the current week and the current number of seconds that we are into that week. This allows the receiver to convert the date and time into the day, month, and year. However, the field that contains the week number has a limited range. It can send to from week number 0 – 1023, or 1024 total weeks.

GPS week zero started January 6, 1980. The 1024 weeks counter ran out and rolled over in August 1999. It then reset to zero, and it has been counting up since. However, on 6th April 2019 the count will reach week 1023 and rollover to zero again.

The wrong place at the wrong time

Most modern GPS receivers shouldn’t be affected by the rollover. However, old GPS receivers that have not had their firmware updated may interpret this rollover as the date going back to January 6, 1980, or possibly some other incorrect date. Is this the opportunity to go ‘Back to the Future’?!

Not only will the GPS receiver start reporting the incorrect date, it may also give incorrect location data. This is because accurate timing is critical to gaining precise location data (an error of only a nanosecond in GPS time can equate to 0.3m of position error). As a result, an incorrect interpretation of this rollover can have big consequences with positional accuracy.

Update or go ‘Back to the Future’

The GPS devices and timing systems on sale at the moment should not be affected. However, older GPS based systems may require a firmware upgrade…unless you want to whizz back to the 1980’s, for DeLorean cars, hover boards and some great fashion!