Home » News » Upcoming Global Positioning System WeekNumber Rollover Event

The GPS Internal Navigation Time Scale “GPS Time” is based on the weighted average of GPS satellites and ground station clocks. GPS Time is used for user navigation solutions. A nanosecond error in GPS Time can equate to one foot of position (ranging) error. The WN parameter is provided via a ten (10) bit parameter–or “counter.”The valid range of values for the WN parameter is 0 to 1023 (or 1024 total values). The WN parameter is incremented by one each week. At the end of the 1024thweek, the counter experiences a rollover (resets) to 0. Each WN rollover event defines a new GPS Time Epoch. The WN value is referenced to the start of the current GPS Time Epoch. The last WN rollover was August 21, 1999. GPS Time is currently in the second Epoch. The next WN rollover is April 6, 2019.

Source: https://ics-cert.us-cert.gov/sites/default/files/documents/Memorandum_on_GPS_2019.pdf

The GEOsat recommends that you, regardless of the manufacturer, play a current firmware to the GNSS receivers to take into account the upcoming GPS week rollover.

If you need assistance for this, we will be happy to assist you at any time.