What is WNRO?

Since its launch, the GPS satellites have transmitted signals that use a 10-bit binary counter to represent the GPS Week Number, a key piece of the date and time information. Every 19.7 years this week number counter reaches its limit and rolls back to zero. The rollover event requires special testing and validation using simulation techniques to ensure that it is properly handled by GPS receivers. A GPS receiver that does not have compliant firmware may experience errors.

The first GPS WNRO event occurred in 1999, and we are now approaching the second WNRO, which will occur on April 6, 2019, at GPS Midnight.

How will this impact my Trimble Products?

Trimble is committed to thoroughly validating our products for WNRO readiness and supplying accurate information to our resellers and customers.

As part of our WNRO testing, we designed a number of assessment plans that use GNSS simulators to verify that receiver firmware correctly handles the week rollover in different scenarios, including real-time kinematic and static surveys with various input and output messages, as well as data file format conversions.

Our analysis determines whether a particular product is Compliant, Upgradable or Noncompliant.

A product is “Compliant” if Trimble has analyzed it and believes that the product will not produce errors as a result of the GPS WNRO occurring on April 6, 2019.

A product is “Upgradable” if Trimble has determined it can be made Compliant via existing software or firmware updates that are installable by Trimble, Trimble dealers/distributors or by the user, without hardware modification.

A product is “Noncompliant” if it is neither Compliant nor Upgradable as defined above.

Whether a product will be affected by WNRO or not, we will make the status known through reseller Support Bulletins and by publishing it on this website.

If a product needs an update, we’ll provide information on the required upgrades and the processes to complete the upgrade through your reseller or account representative.

If a product is obsolete and cannot be upgraded, we’ll work with your reseller or account representative to find alternative solutions.