GPS Week Rollover

March 20th 2019
GPS Week Rollover

What is GPS week rollover?

Occurring 6 April 2019, the transmitted GPS week number in the navigation message will rollover from 1023 to 0. The GNSS receiver must be able to handle this rollover otherwise it could result in an incorrect receiver date of 21/22 August 1999 (1024 weeks back). This wrong date might cause incorrect measurements and observation data.

The Global Positioning System (GPS) week number rollover occurs in the GPS legacy navigation (LNAV) message every 1024 weeks due to the GPS week number being represented by only 10 bits within the LNAV message. The next GPS week number roll over will occur 18 seconds prior to the 0000Z boundary (Coordinated Universal Time) between 6/7 April 2019.


What to expect:

GNSS receivers must be able to handle this rollover otherwise it could result in an incorrect receiver date of 21/22 August 1999 (1024 weeks back). This wrong date might cause incorrect measurements and observation data. Using a GPS signal generator, GeoMax simulated the upcoming GPS week rollover.

GeoMax advises that GNSS receivers running the latest firmware are not expected to encounter any issues.

You should ensure your GNSS is running the latest firmware version before this time.


What do GeoMax GNSS users need to do?

If you are using one of the below GeoMax GNSS receives and have up to date firmware, you do not need to do anything and should not experience any issues on 6/7 April.

If your GNSS firmware is out of date, we recommend updating before GPS week rollover by contacting our support team.

GeoMax GNSS Receivers:

        • Zenith20
        • Zenith15/Zenith25/25 Pro
        • Zenith35/35 Pro

GPS Week Rollover


Contact our support team at info@buildmax.co.nz or call 0800 443 6629


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