Could the approach of linking phones to create a singular, extensive distributed antenna assist in thwarting Russian electronic warfare tactics?

As reported by an American organization developing a system in Ukraine, networked cell phones that operate on specialized software might offer a low-cost and easily implementable counter to the advanced electronic warfare techniques used by Russia.

The use of electronic warfare by Russia, including techniques such as signal jamming and GPS spoofing, complicates the operational landscape for Ukrainian forces, hindering their ability to effectively utilize drones and high-end U.S. weaponry. Detecting and identifying enemy jamming equipment usually requires advanced software-defined radios, which are commonly supplied to the United States and other financially capable military entities. In contrast, smaller militaries like Ukraine's find it challenging to secure these necessary tools in sufficient numbers due to limited budgets.

If a low-cost system is developed to pinpoint enemy jamming devices, it could empower Ukrainian operators to recover some tactical advantage against their more heavily armed opponents. This development might also reshape the strategies of cellphone network providers in reinforcing their devices against advanced attacks.

Near Christmas of last year, the Ukrainian military reached out to Sean Gorman and his team at Zephr, a company known for its expertise in protecting devices from GPS-signal interference. Zephr promptly sent six Android Pixel phones, loaded with their software, to Ukraine, and in April, they started field tests in areas adjacent to the frontlines in Donetsk.

Gorman conveyed to Defense One that the phones were mounted on drones, incorporated into cars, and arranged on stationary stands. They have also engaged in controlled experiments where their own jamming devices were used, enabling them to pinpoint the location.

The primary focus was to explore if regular consumer phones, working collectively in a network, could indicate the presence of an entity trying to disrupt GPS location data. The results showed that by comparing the GPS reception among different devices, they could detect when one or more phones were under threat.

As Gorman explained, "Our methodology primarily revolves around exploiting the sensors present in the phone. The most crucial sensor is the raw data from the global navigation satellite system (GNSS) that the phone provides. This includes automatic gain control (AGC), Doppler information, carrier phase, code phase, and other data that mobile devices collect concerning their distance from satellites, cellular towers, and other network equipment."

To optimize performance, manufacturers install these sensors in mobile phones, allowing them to identify the nearest cell tower. The measurements obtained are crucial for the GPS-processing software that informs users of their location. By gathering data from a broad spectrum of phones, one can ascertain which devices are potentially under attack.

As Gorman explained, the computational AI we have implemented in the backend, along with the complexity of our signal and software processing, provides extensive capabilities. Instead of relying solely on sensors or prohibitively expensive antenna arrays, there is a significant advantage in connecting phones to operate as a single, large distributed antenna.

The analyses revealed additional insights into the realm of Russian electronic warfare.

The Baltic Sea is witnessing Russian interference with GPS signals, leading to the display of incorrect location data by receivers. NATO officials have described this as a perilous situation for commercial aviation. A frequent countermeasure against drones is the spoofing of GPS signals, which causes the drone to erroneously perceive that it is above an airport, thus requiring it to land or vacate restricted airspace.

Soldiers in Donetsk, Ukraine, regularly report encountering spoofing attacks targeting their drones. However, Gorman and his team have found that much of this "spoofing" is actually attributable to high-powered jamming attempts. These jamming activities occur within the same frequency bands as GPS or GNSS, which allows them to imitate satellite signals. This phenomenon results in the appearance of phantom or ghost satellites in areas where they cannot logically exist and still deliver a signal, such as beneath the horizon.

In a report to Defense One, Gorman explained that the noise detected does not resemble a conventional GNSS signal, although it does contain energy at the frequencies the receiver is scanning for satellite signals. The signal-processing algorithms of the receiver apply correlation techniques to discern and track these satellite signals. When a powerful jamming signal is introduced, it can create false correlations, leading the receiver to erroneously conclude that it is detecting satellites that are not actually observable.

Currently collaborating with the Ukrainian government under a contractual agreement, the group is focused on advancing their research to go beyond the detection of signal jammers, aiming to pinpoint their locations for potential avoidance or eradication.

According to Gorman's email, the new techniques being developed will estimate the location of signals of interest using three inputs: 1. localization by range inferred from power; 2. localization by area of effect; and 3. triangulation of jammers based on the angle of arrival. Each smartphone will identify the interference signal, record the last known position, and timestamp the reception, generating data points across the network. By aggregating and processing these signals centrally, the system will triangulate the position of the cell phone jammer.

The U.S. military is channeling substantial funds into alternatives to GPS, often called alternative position, navigation, and timing (Alt PNT), to enable individuals, drones, and other entities to determine their precise locations. Unfortunately, many of these investments have not proven to be particularly fruitful.

As Gorman pointed out, the operation cannot proceed without a predetermined known position, and it is nearly impossible to determine this position without GPS.

The proposed networked approach will not take the place of other, more costly military systems that are utilized for the detection and identification of jammers. However, it does provide a solution that can be implemented swiftly and economically for military organizations such as Ukraine, as well as other groups that may face disruptions from jamming activities, including first responders. Additionally, while it will not replace the pursuit of alternative position, navigation, and timing methods, it may contribute to their improved effectiveness.

Gorman indicated that there could be a radically different perspective to consider. Instead of funneling all resources into Alt PNT and GNSS resilience, which are indeed useful, we might want to assess how this has become a reality. He stressed the importance of mapping and understanding the area in relation to the emitters, which would enable us to steer clear of those areas and remove the emitters.