A group in Ukraine is testing the newest weapon against GPS jammers: cell phones

An American company working with the Ukrainian military is developing a cheap and easy-to-implement solution to Russia’s sophisticated electronic warfare tactics: networks of ordinary cell phones running special software.

The software allows mobile phones to pinpoint enemies using jamming equipment, and if the experiment is successful, it could help operators in the field gain at least some advantage against better-armed enemies in the age of electromagnetic warfare. This could transform the way mobile phone network providers ensure their devices are resilient to sophisticated attacks.

Russia’s electronic warfare measures are having a detrimental effect on the ability of Ukrainian troops to repel the Kremlin’s invading forces; Armed with state-of-the-art US weapons. And it can even be difficult to detect when drones or other equipment are malfunctioning due to signal jamming, GPS spoofing, or simply internal issues.

Detecting and locating enemy jamming devices often requires high-end software-defined radios; This is the kind of equipment that the United States and other well-funded militaries can give their troops, but smaller militaries with tight budgets like Ukraine’s have a hard time acquiring it. big numbers.

Around Christmas, the Ukrainian army reached Sean Gorman and his group. zephrA company that specializes in making GPS signal reception more resistant to interference. The group shipped six Android Pixel phones loaded with Zephr software to Ukraine in early 2024 and began field testing near Ukraine’s front lines in Donetsk in April.

“We connected these phones to drones. We put them in the cars. We set up permanent stands for them, and we also do controlled experiments where they use their own jammers, so we know where it is,” Gorman said. Defense One. The first goal: to see if regular consumer phones working together in a network can reveal the presence of an entity trying to spoof GPS location data, even if the location data appears accurate on any device.

They measured how well phones in motion (attached to a drone and carried in a car) received GPS signals compared to static phones. Findings: It is possible to detect when specific GPS receivers have experienced an attack by comparing their GPS traces with those of other phones.

“We’re basically leveraging the sensors in the phone,” Gorman explained. “The most useful sensor on the phone is the raw (global navigation satellite system, or GNSS) measurements that the phone provides. So there is you AGC, automatic gain control, there is Doppler (sensor)there is carrier phasethere is code stage,” and other data mobile phones collect about their distance to satellites, cell towers, and other network equipment.

Manufacturers are embedding these sensors in mobile phones so that the phone can understand how to optimize performance by, for example, detecting where the nearest cell tower is. But all of these measurements play a role in the GPS processing software that phones use to tell the consumer where they are. When you can get this data from a wide variety of phones, you can tell which ones are under attack.

“Thanks to the computational AI we run on the backend and the complexity of how we process most signals and software rather than just relying on sensors or really expensive antenna arrays, there’s a lot you can do in networking phones coming together as one big distributed antenna,” Gorman said.

The tests also revealed new information about Russia’s electronic warfare efforts.

Russia spoofs GPS signals in the Baltic Sea What NATO officials have It is described as unsafe for consumer aircraft. Fake GPS not only blocks the signal. It tells the buyer that they are somewhere they are not.

Often, when competitors try to spoof GPS locations for drones, they will tell the drone that it is actually at an airport because most consumer drones are built for landing or retreating from restricted airspace.

Ukrainian soldiers on the front lines in Donetsk report frequently spoofing attacks targeted their drones. But Gorman and his team found that much of this “spoofing” activity was actually just high-powered jamming attempts. Because these initiatives take place in the same place. Frequency bands as GPS or GNSSThey appear as satellite signals, effectively creating phantom or phantom satellites in places where they are unlikely to exist and still provide signals, such as below the horizon.

“This noise does not resemble a typical GNSS signal, but it contains energy at the frequencies where the receiver searches for satellite signals. The receiver’s signal processing algorithms use correlation techniques to identify and track satellite signals. When a strong jamming signal is present, it can cause false correlations, which can lead the receiver to ‘think’ it is detecting satellites that are not actually visible,” Gorman explained in a post on the test Defense One.

The group, currently working under a contract with the Ukrainian government, is trying to take the research a step further to not only identify jammers, but also triangulate their locations so they can avoid (or eliminate) jammers.

“The new techniques we created will estimate the location of signals of interest using three inputs: 1. Localization by range from power 2. Localization by area of ​​effect, and 3. Triangulation of jammers by angle of arrival,” said Gorman. an email.

“Each smartphone will detect the jamming signal, log the last known location, and timestamp the reception, providing data points across the network. “The system will triangulate the location of the jammer by centrally collecting and processing these signals.”

The U.S. military has a mission to combat humans, drones, etc. is investing heavily in GPS alternatives, often called alternative location, navigation and timing (or Alt PNT), to help people understand where they are. But investments in many cases it did not show a large return.

“None of them work without a known location to begin with. Without GPS, it’s nearly impossible to get a known initial location, Gorman said.

This networked approach won’t replace other, more expensive military systems for detecting and finding jammers, he said, but it does offer a solution that can be deployed quickly and cheaply for militaries like Ukraine or other groups that might be disrupted by jamming activity. Like first responders. Although it does not replace efforts to develop alternative location, navigation, and timing methods, it can make them more effective.

“Maybe there’s a completely different way to think about this? Instead of spending all the resources on Alt PNT and GNSS flexibility, which are all very useful, maybe we can look at how this is now a reality? “How well can we map all of this and understand the area where the emitters are so we can escape those areas and eliminate the emitters?” Gorman said.

But “there is no (silver) bullet,” he said.