Roll over, Eindhoven. And tell tectonics to move.

November 6, 2018  - By
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A free lesson for those in charge of critical infrastructure systems such as the power grid, communications, financial markets, emergency services, and industrial control.

Many of these systems have functioned smoothly and efficiently for years, thanks to the precise timing provided by GPS receivers. That could change, suddenly and without warning, if predictive and preventative steps are not taken.

The GPS receivers somewhere near the hearts of these critical systems, if not thoroughly vetted, tested and checked for up-to-dateness, could constitute a vulnerability — a vulnerability that would be catastrophically exposed on April 6, 2019. In 6 months’ time.

Image: Orolia

Image: Orolia

The GPS constellation transmits the proper date and time to all receivers, worldwide, by supplying the current week and the current number of seconds into the week. This enables the receiver to translate the date and time into a more typical format: day, month, year, and time of day. Infrastructure systems use the precise timing to synchronize many complex operations across their respective networks. Critically, the field that contains the week number is a 10-bit binary number. This limits the range of the week number to 0 – 1023, or 1024 total weeks.

GPS week zero started January 6, 1980. The 1,024 weeks counter ran out and rolled over on August 21, 1999. The week counter then reset to zero, and it has been recounting ever since. The next time the counter will reach week 1,023 and roll over to zero is on April 6, 2019.

If the GPS receiver is new or has received firmware updates, it can accommodate and adjust for this change. But do you know for sure? Only if you test. Otherwise, your critical systems may go into a time warp, 19.7 years out of date. Visualize that discrepancy rippling outward from the core component of a critical timing system throughout your infrastructure. Or, simply not working at all.

It is incumbent upon all managers to verify that such an issue will not occur — well before its possibility arises. At a minimum, experts recommend consulting your receiver manufacturer to confirm that the issue has been fully tested and will not occur. Many manufacturers have already issued compliance statements, and are expected to continue doing so over the next year, up until the event occurs.

To be sure that your system will not experience any failures related to this issue, it is possible to test for this event using a GPS/GNSS simulator. The requirements for the simulator are straightforward. The basic yet key information necessary to undertake such testing will be communicated in a free webinar on Thursday, November 15.

The panel of expert speakers includes Lisa Perdue, product manager and applications engineer, Orolia; Stefania Römisch, leader, the Atomic Standards Group at the National Institute of Standards and Technology; and Dana Goward, president, Resilient Navigation and Timing Foundation.

You may register for this free webinar here, to attend it live or download it for later viewing at your convenience.

Here is a useful reference from the last time the rollover occurred, with a mention of the next one.

Photo: Technical University of Eindhoven

Photo: Technical University of Eindhoven

Eindhoven, the Netherlands, is home to the Eindhoven University of Technology, an incubator for technology startups where many scientists active in GPS research and in the direction of the Galileo satellite navigation program have trained.

Tectonics is the study of plates in the Earth’s crust that move in different directions and speeds. To study plate motion, GPS instruments are anchored firmly in bedrock to measure how it moves, infinitesimally yet measurably, thanks to the nanosecond timing provided by the GPS constellation and interpreted by properly calibrated and updated instruments.

Roll over, Beethoven.

About the Author:


Alan Cameron is editor-in-chief and publisher of GPS World magazine, where he has worked since 2000. He also writes the monthly GNSS Insights column for the weekly Navigate! e-newsletter.

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