Take note: GPS week number rollover on 6 April 2019

April 4th, 2019, Published in Articles: EE Publishers, Articles: PositionIT, Featured: EE Publishers

Global Positioning System (GPS) users and those who use systems relying on GPS should be aware of the upcoming GPS week number rollover which will occur on 6 April 2019 at 23:59:42 UTC, during which the GPS week counter will reset to zero.

GPS uses a week counter to calculate date. This value is encoded as a 10-bit field in each message broadcast by GPS satellites to receivers on earth, i.e. counted from 0000 to 1023. Once the counters reaches week 1024 (i.e. every 19,7 years) the week counter value resets to 0000.

The rollover could result in GPS or timing errors such as slower initialisation time and incorrect date records. Users are advised to update their firmware and controller software to minimise the impact of GPS rollover. Receivers that are not manufactured in compliance with IS-GPS-200 specifications may be affected.

The GPS Innovation Alliance expects that GPS-enabled equipment with current firmware should not experience issues with to the rollover. Manufacturers including Topcon Positioning and Sokkia, Trimble, DJI, Here Technologies, TomTom and  Microsoft, among others, have all addressed the issue or tested their equipment and services to ensure it will not be affected by the rollover.

A similar reset occurred once before on 21 August 1999. While that rollover had little impact on other functions, various systems and technologies have since become a lot more reliant on GPS. May commercial applications use GPS as the de facto time standard, including sectors and operations such as telecommunications, cloud operations, aviation, rail and maritime, multi-rate billing, ATM network, cryptography and smart devices, among many others.

Besides being aware of the rollover and ensuring your software and firmware is updated, you can contact your GPS receiver manufacturer to ensure the device will not be affected.

What the GPS week number rollover does seem to highlight is the need and importance of resilient design, especially for the engineering of critical systems. This idea is discussed in length with relationship to the GPS rollover in this video: https://www.youtube.com/watch?v=Aj9ZtdQ2g20

More resources


[1] “Are You Ready for the Next GPS WNRO (Week Number Rollover)?,” Masterclock, Inc. [Online]. Available: https://www.masterclock.com/company/masterclock-inc-blog/2019-gps-week-number-rollover. [Accessed: 03-Apr-2019].
[2] O. Luft, “Everything you need to know about GPS Week Number Rollover.” [Online]. Available: https://360.here.com/everything-you-need-to-know-about-the-impending-gps-wnro. [Accessed: 02-Apr-2019].
[3] “GPS Innovation Alliance Blog,” GPS Alliance. [Online]. Available: https://www.gpsalliance.org/blog/gps-week-number-rollover-explained. [Accessed: 04-Apr-2019].
[4] “GPS Rollover Week | GPS Innovation Alliance (GPSIA),” GPS Alliance. [Online]. Available: https://www.gpsalliance.org/gps-rollover-week. [Accessed: 04-Apr-2019].
[5] “GPS Week Number Roll Over,” Department of Homeland Security, 26-Mar-2019. [Online]. Available: https://www.dhs.gov/cisa/gps-week-number-roll-over. [Accessed: 04-Apr-2019].
[6] “GPS Week Number Roll-Over,” TomTom Community! [Online]. Available: https://discussions.tomtom.com/en/discussion/1108335/gps-week-number-roll-over/p1. [Accessed: 04-Apr-2019].
[7] “GPS Week Number Rollover – Microsoft has you covered!” [Online]. Available: https://azure.microsoft.com/en-us/blog/gps-week-number-rollover-microsoft-has-you-covered/. [Accessed: 04-Apr-2019].
[8] “GPS.gov: News Items.” [Online]. Available: https://www.gps.gov/news/. [Accessed: 30-Mar-2019].
[9] “GPSRollover,” Topcon Positioning Systems, Inc., 05-Feb-2019. [Online]. Available: https://www.topconpositioning.com/gpsrollover. [Accessed: 03-Apr-2019].
[10] “Statement on GPS 2019 Week Rollover (6 April 2019),” DJI Official. [Online]. Available: https://www.dji.com/newsroom/news/statement-on-gps-2019-week-rollover. [Accessed: 30-Mar-2019].
[11] L. Perdue, “The GPS 2019 Week Rollover – What You Need to Know,” Orolia, 18-Dec-2017. [Online]. Available: https://www.orolia.com/resources/blog/lisa-perdue/2018/gps-2019-week-rollover-what-you-need-know. [Accessed: 04-Apr-2019].
[12] “Trimble GPS Week Number Rollover (WNRO).” [Online]. Available: https://www.trimble.com/wnro/. [Accessed: 04-Apr-2019].

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