GNSS Week Rollover

GNSS Week Rollover
 
 
On the 6th April 2019, the transmitted GPS week number in the navigation message will rollover from 1023 to 0000. Leica Geosystems GPS/GNSS receivers should not be affected by this rollover.

To guarantee you will be unaffected by this rollover, please ensure your equipment is updated to the latest measurement engine firmware.

Please refer to the myWorld portal to obtain the latest firmware. A guide to myWorld is available here.

For any questions or assistance, please contact uk.support@leica-geosystems.com or your local supplier.
 
WHAT IS HAPPENING? 
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. 
 
WHY IS THIS ROLLOVER HAPPENING?
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 April 6/7 2019. 
 
HOW DID LEICA GEOSYSTEMS PREPARE FOR THE WEEK ROLLOVER?
The week rollover has been simulated using a GPS signal generator. Tests have been done with Leica Geosystems GNSS receivers introduced since 2004. This includes the System 1200, GPS900, Viva GNSS and GR/GM/GG product families. The latest firmware versions were installed in all tested receivers. 

Based on the performed tests, we do not expect that the GPS week rollover will cause any issues regarding signal tracking, positioning or observation data logging. 
 
WHAT CUSTOMER ACTIONS ARE NEEDED TO ENSURE THEIR OPERATIONS WON'T BE DISRUPTED? 
To guarantee you will be unaffected by this event, please ensure your equipment is updated to the latest measurement engine firmware. To confirm if your firmware is up to date, please refer to the myWorld portal.

If your GPS/GNSS equipment has been serviced with a Customer Care Package (CCP) in the last year, no action is necessary.