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Technical Notices
Global Positioning System (GPS) Week Rollover Event
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On 6 April 2019, how Global Positioning System (GPS) devices display time may be affected by a change in the GPS navigation message signals.
The way GPS broadcasts time and date information involves a 10-bit week number (0-1,023), which resets or “rolls over” every 1,024 weeks or approximately 19.6 years. The next week number rollover will occur on 6 April 2019.
The 2019 GPS Week Number Rollover could have a potential effect upon GPS receivers (including GPS sensors and GPS receivers embedded within multifunction displays, chart-plotting products, AIS receivers and VHF radios) and any of their features dependent on date/time information.
Owners of ships fitted with equipment reliant on GPS signals, should:
- Ensure the equipment’s firmware is up to date
- Contact the manufacturer to ensure the equipment will not be adversely affected by this event.
For further information see Department of Homeland Security release of the memorandum titled U.S.Owners and Operators Using GPS to Obtain Time
