Get ready for GPS Week Number Rollover (WNRO)

 GPS Week Number Rollover – WNRO


Get ready for GPS Week Number Rollover (WNRO)


We would like to inform our clients about GPS Week Number Rollover (WNRO). Be prepared for this change.

When will the GPS Week Rollover Occur?

The GPS Week Rollover event will occur on April 6, 2019 at 23:59:42 UTC.

This will be the second global event of its kind and will affect all users of Global Positioning System (GPS) technology regardless of brand. The last GPS Rollover Week event was in 1999. The next will occur in another 19.7 years.

What is the GPS Week Rollover?

The GPS satellites send a 10-digit binary communication message toward Earth with a “week number” counted from 0000 to 1023. Once the maximum coded week of 1024 is reached (which takes 19.7 years), the week number value resets to 0000. 

What impact is expected?

With the wide variety of GPS technology applications in use today, the impact to users will vary depending on the use case, e.g., surveying with a base and rover receiver, machine control, OEM placement, or precision agriculture. Impacts such as slower initialization time and incorrect date records can be expected for some receiver and software combinations if the firmware and software are not updated to the latest available versions. In most cases an update to the latest receiver firmware and latest versions of software are recommended.

What action to take?

The firmware and/or software for devices using external GPS clock information will need to be prepared to accommodate this rollover. Support and development resources have been actively working to provide the best solutions possible for minimizing impact to users of Topcon and Sokkia GPS technology.