GPS Rollover Week

Accurate data underpins the modern economy

The Global Positioning System (GPS) Rollover Week begins this Saturday 6th April. What does that even mean I hear you cry? 

It means that there is a chance your GPS device might start acting a bit weird. Jumping backwards in time………. not literally, sorry budding time travellers! More likely some GPS receivers may start to behave strangely as their time stamps on data may revert 20 or even 40 years. Some may not be able to cope at all and shut down. 

 

What is causing all of this? 

It is all due to how GPS manages and measures weeks in the navigational signals they transmit. All week numbers are encoded in a form that can represent a maximum of 1,024 weeks.  Once this number is reached, a GPS device reverts its count to zero and starts counting again. 

1,024 weeks equals 7168 days, or approx. 235.7 months, or approx. 19.6 years. 

This 7,168-day period of time is referred to as an ‘epoch’, a continuous time system for all satellites, observation and GPS systems. Still here? Good. 

 

When did this last happen? 

That is easy, 21st August 1999, which was about 19.6 years ago, Do you see where I am going here? 

The good news is that this has been known about for a while, and in fact this is the second time it has happened. The first count started on January 6th 1980, when GPS went live, and reached the end of its first epoch August 1999. We are now 20 years (or 1 epoch) further on and many GPS manufacturers will have updated their devices to deal with the rollover. 

 

So, what are the potential consequences? 

Though unlikely to cause serious consequences, utility, telecommunications, transport and government agencies could all be affected. The rollover is not expected to affect the receiver’s ability to navigate but does have the potential to give wrong timestamps. In turn, this may affect applications where time is a crucial aspect of the location data. Renewals, asset lifespan are just two broad examples of applications dependent upon date data. 

To describe the potential implications of inaccurate data, to the effective functioning of hardware associated with underpinning the global economy, as serious, is probably selling it a tad short. 

Examples like this remind us of the immense importance that spatial data plays in our world and why data accuracy should be a crucial part of any companies’ business practice.  

 

Data accuracy 

At 1Spatial we believe data accuracy and data governance across small or enterprise level business is vital to any organisation. Particularly as geospatial data becomes increasingly central to decision-making for both business and the consumer. 

1Spatial has spent over 40 years working with the largest geospatial databases in the world. Our unique, rules-based approach delivers enterprise-scale, cross-platform, automation to all stages of the data lifecycle. It builds confidence in the data while reducing the time and cost of management. 

We help land management and national mapping agencies, transportation organisations, utility companies, defence departments and the governments of countries, regions and cities to collect, store, manage and interpret location-specific information. Our open approach to data excellence ensures that our tools, processes and the data we manage work seamlessly with other leading players in the geospatial sector. 

 

Written by Iain Brackenridge, Project Manager at 1Spatial.

Share this page