The GPS system is synchronized to a different time scale than Coordinated Universal Time (UTC) and calculates time by counting the number of weeks up to 1,023 weeks.
After week 1,023, the receiver will reset the week number to zero and start counting again.
The subsequent inexact date information on GPS receiver clocks may result in positioning instability, causing position errors including the failure of GPS position acquisition. Moreover, positions with historic or future dates will not display on our systems.
This is called "GPS week number rollover", which will be happening on 6 April 2019.
Who will be affected?
GPS tracking devices installed could cause system errors if they start to provide location data that is potentially up to 20 years out of date.
Issues could occur if:
- Receivers have been in operation for more than 10-15 years without firmware updates
- Receivers are part of a critical timing system
This situation won’t affect a receiver’s ability to navigate and/or calculate precise time, but it has the potential to create week, month and year timestamps that are incorrect. Applications which rely on GPS data at that level may be seriously affected.
Other GNSSs, such as the Russian GLONASS, European Galileo or Chinese BeiDou, are not affected by this problem.
What can be done?
Some manufacturers will have created a patch or workarounds. If you experience GPS related issues the best advice is to check with the manufacturer of the devices you use.
Please refer to the manufacturer list below for units tracked by Pole Star.
Units tracked by Pole Star & who to contact
SKYWAVE / Orbcomm
Skywave have confirmed that DSAS MK2/IDP-690/ST6100/ units will not be affected, as well as DSAS MK1/ ISAT M2M devices from after 2008.
For any issues with please contact the Pole Star customer support team.
Some manufacturers have identified a handful of older units which may experience GPS date reporting problems. Individual manufacturers may provide a work around for affected units. Please find below some useful links.
Global Star confirm that there will be no issues with any of their Pole Star supplied units.
For any issues with please contact the Honeywell (Satamatics) support team.
Iridium have confirmed no GPS related issues with LRIT units tested and tracked via Pole Star
For further guidance or any issues please contact the Transas support team.
Newer AIS units should be future proofed however older units may experience issues and you should refer to the manufacturers website for further guidance regarding potential patches or upgrades.