A new University Transportation Center at Ohio State University is tackling the vulnerabilities of technologies that depend on the Global Positioning System (GPS), which relies on signals from 24 satellites to provide positioning, navigation, and timing (PNT) services. Launched in 2020 through a $2 million grant from the U.S. Department of Transportation, the Center’s first conference took place this month in Columbus.
The Ohio State team is directed by Professor Zak Kassas and includes Professors Todd Humphreys and Chandra Bhatt from the University at Texas at Austin. Researchers are seeking to answer the basic question of how we know that the data that we are getting on our navigation devices is correct, and how to provide alternatives to GPS. Finding alternative sources allows users to check one set of signals against another to ensure accuracy.
This work is vital because national security and civilian infrastructure depend on GPS, and GPS is open to intentional and unintentional interference. Consider that drivers, emergency workers, truckers, sailors, and pilots use GPS for navigation. Electricity producers use GPS to synchronize systems at power stations. Farmers uses GPS to put seeds down in a specific location, and then fertilize and water those seeds. Builders use GPS to put studs and nails in precise points in construction projects, to avoid errors and lower costs.
GPS “jamming” drowns out the signal, so, as people are driving or flying, their navigation system might disappear. GPS “spoofing” can feed realistic information to users, and trick them into going to another location. This happened in 2019, when the Iranians conned a British tanker, Stena Impero, into believing the ship was in international waters, when in reality it was in Iranian waters. The tanker was picked up by the Iranians and the British crew imprisoned for 10 weeks.
At Israel’s Ben Gurion Airport in 2019, pilots had to use alternative instrument systems when landing because their GPS receivers reported an alternative location. The spoofing was linked to Russian jamming systems to protect its planes at Hmeimen Airbase, in Syria, 217 miles north of Ben Gurion Airport, according to the BBC. Russia announced this system in 2015, to protect its planes from drones.
It used to be that this interference was difficult to accomplish because of the costly technology required. But now portable software defined radios can imitate GPS satellite signals and are relatively inexpensive. The NooElec HackRF One Software Defined Radio costs $325 on Amazon.com, and the description states that the radio “has not been tested for compliance with regulations governing transmission of radio signals. You are responsible for using your HackRF One legally.”
The Ohio State team is exploring how to use 5G for navigation, which can result in fewer delays and more reliability. Researchers have developed a method to use signals sent by Low Earth Orbit internet satellites, such as Starlink, Orbcomm
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This research fits in with the new Space Policy Directive 7, issued in January. It calls for performance monitoring and interference detection for civil space-based services; resiliency; PNT data and signal authentication; and PNT requirements for civilian applications. Plus, in August the White House National Science and Technology Council issued a National Research and Development Plan for PNT Resilience, a plan to improve the resilience of PNT services and the critical infrastructure that depends on such services.
The Executive Branch and Congress are trying to prevent companies from locating next to the GPS band and degrading the signal. A 2020 Federal Communications Commission order granted an application from Ligado Networks, a Virginia-based company, to operate a terrestrial spectrum network next to the bands reserved for GPS. Interference will occur because Ligado’s signals will be two billion times as powerful as received GPS signals from satellites.
The National Telecommunications Information Administration, part of the Commerce Department, on behalf of the entire Executive Branch, filed a petition asking the FCC to reconsider the Ligado approval, citing “irreparable harms to federal government users of the Global Positioning System.”
The FCC’s order required Ligado to pay for damages to federal devices, but not to reimburse individuals and companies — costs that could run into the tens of billions of dollars. Senator Jim Inhofe (R-OK), has sponsored the bipartisan RETAIN GPS and Satellite Communications Act, S. 2166, with Senator Tammy Duckworth (D-Ill) and Mike Rounds (R-SD).
The bill would hold Ligado, or a future licensee if Ligado chooses to sell the spectrum, responsible for costs to non-federal users as well as federal users. Representative Jim Cooper (D-TN) has introduced a parallel bill in the House of Representatives, HR 4634.
Senator Inhofe told me in an email, “We rely on GPS for too many essential functions to jeopardize how it is used by government, private entities and consumers. When Ligado’s effort to repurpose spectrum causes interference in the infrastructure of those systems, as tests have shown it will, consumers and taxpayers shouldn’t bear the burden of updating countless systems. That cost should only be borne by the responsible party: Ligado. I hope that our legislation can be considered soon; we can’t afford to wait.”
The world is an increasingly dangerous place. Ohio State’s new research will make it a little less so.
