GPS Rollover Event May Cause Devices, Systems To Go Haywire

By Juliette Goodrich

April 2, 2019 at 9:27 pm

Tnx to Jim K2ZO for this

by Juliette Goodrich and Molly McCrea

(KPIX 5) — On or around April 6th 2019 , will your handy-dandy global positioning system (GPS) device be working properly?

Or, if you’re driving south on U.S. Highway 101, heading to your job in San Jose, will your GPS show your car is traveling to the Farallon Islands?

If you’re on a hike in the Coyote Hills, will your GPS device display that you are walking around at the Stanford Shopping Mall?

Here’s the deal: if your GPS begins to go a little haywire around this time, you may be experiencing what’s called “GPS Week Rollover Event.” The issue may remind us how much the world relies on GPS.

But, with the GPS rollover event, you may want to stash a few in your car. It’s the GPS version of a mini-Y2K. Devices at highest risk for failure include the older devices or the devices that have not been frequently updated.

The imminent system update has the attention of Brad Parkinson, a recalled emeritus Professor at Stanford University and best known as the lead architect, advocate, and developer of GPS.

“First of all, I would say it’s legitimate to be concerned,” said Parkinson.

The California resident is an engineer and an inventor, as well as a retired U.S. Air force colonel.

“GPS affects everything we do,” Parkinson told KPIX 5 in a recent interview at the Marines’ Memorial Club in San Francisco.

GPS is a network of 31 satellites owned by the U.S. government and operated by the Air Force. GPS provides many services for civilian uses, by providing location, and syncing up critical systems back on earth.

“It affects timing, banking, cell towers, airplanes, ships, passengers in cars,” explained Parkinson. “It is affecting everything that we can imagine.”

The power grid, financial markets, delivery trucks, and emergency services all benefit from GPS. In California, public safety agencies, such as the California Highway Patrol and Cal Fire utilize GPS timing at the major dispatch console systems, which is transmitted to field personnel via radio.

USGS officials monitor seismic movement or tectonic plate motion using GPS sensors, which helps locate where a quake has occurred.

“We’re completely reliant upon GPS,” remarked GPS expert Dana Goward, who served as the maritime navigation authority for the United States.

He is currently serving as President of the Resilient Navigation and Timing Foundation or RNTF. The nonprofit is dedicated to protecting, toughening, and augmenting GPS signals.

Goward explained that GPS works by sending out timing signals. On each satellite, there are multiple atomic clocks. GPS relies on precision timing to operate.

“Essentially, all the GPS satellites are just very, very precise clocks,” said Goward.

In that timing signal, there is a timestamp containing a code. The code is based on the week and seconds in that week when “GPS Time” began or was set. That date started on January 6, 1980.

But since “GPS time” uses only 10-bits to count the weeks and seconds within that week, it can only cover a finite period of time before it runs out of space.

“It turns out it happens roughly every 20 years,” said Parkinson.

That finite period of time is 1,024 weeks or precisely 19.7 years. This period of GPS time called an epoch. When GPS time reaches its finite period, it “rolls over” or resets to zero.

This rollover happened once before on or around August 21, 1999, but there were few documented problems, according to experts. This time, it’s different.

“20 years ago, you did not have a GPS in your cell phone,” said Parkinson.

Parkinson estimated that worldwide, there are 4 billion uses of GPS in cell phones alone. The annual benefit to the U.S. economy in terms of productivity is $60 billion.

A GPS rollover event could throw off time by rolling back to the wrong date, disrupt critical systems by throwing them out of sync with time, not to mention make your personal GPS device perform in a bizarre manner.

“If you’re driving your car and it were to suddenly say you’re in the middle of the Pacific Ocean, be very suspicious,” cautioned Parkinson.

The U.S. Department of Homeland Security has published a bulletin warning about the upcoming event and recommending GPS users make sure their devices are properly updated.

Most modern devices should do just fine. An official at California’s Office of Emergency Services told KPIX 5 that the agency has performed an assessment of various public safety agency radio systems and has worked with the manufacturers of the GPS timing receivers. The official said the manufacturers of devices used by Cal OES have assured them the devices will not be impacted by the rollover event.

A U.S. Geological Survey seismic expert told KPIX 5 that some of its older seismic monitoring equipment have already rolled back to a wrong date. The first report of the issue was actually in July 2018. A USGS team discovered the problem when data from these sensors started coming in timestamped not from 2018, but from 1998.

The equipment was beyond its obsolescence point, and the team learned the devices could no longer be supported by the manufacturer with any kind of firmware update.

The team wrote its own software fix, and that went out to all the other regional software networks. The data, according to the USGS official, had to be shifted 1,024 weeks or 619,315,200 seconds, putting the network back in sync.

It’s also important to note just because April 6th comes and goes without any apparent issues with your GPS, that there won’t be a rollover. Experts caution how actual errors may kick in before or later.

The good news is that GPS manufacturers are well aware of the upcoming issue, Parkinson said. He added if you’re operating a company and remain unsure about whether the rollover will impact you, you can get a GPS/GNSS simulator that can walk your network through the event and you can see if there is a glitch or not. This could save you a major headache. (link two examples of companies that make GPS simulators)

In the future, the modernized GPS navigation messages will use 13-bits instead of 10-bits. Experts explain that will push rollovers to roughly every 157 years instead of the current 20.

The best advice: trust but verify that your GPS device is updated, don’t panic and have a backup plan. It’s never too late to learn how to read a paper map.

And, while it may sound melodramatic, in times of any major disaster, if GPS goes down for a prolonged period of time, it’s a good skill for everyone to know how to navigate using the sun, moon, and stars.

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