Can the idea of uniting phones to act as one large distributed antenna be a viable method for countering the challenges posed by Russian electronic warfare?
An American company focused on system development in Ukraine has proposed that networked cell phones running dedicated software could act as a budget-friendly and simple countermeasure against the sophisticated electronic warfare tactics of Russia.
Russian electronic warfare methods, such as signal jamming and GPS spoofing, significantly hinder the operational capabilities of Ukrainian troops, affecting their ability to deploy drones and utilize advanced U.S. weaponry. The detection and identification of enemy jamming devices typically demand high-quality software-defined radios, which are readily available to the United States and other well-funded military forces. However, smaller militaries, including Ukraine's, face considerable challenges in acquiring these essential technologies in adequate quantities due to financial constraints.
The establishment of an economical system designed to locate enemy jamming equipment could significantly aid Ukrainian operators in regaining an upper hand against their better-armed foes. Moreover, it could lead to a reevaluation of how cellphone network providers secure their devices against sophisticated threats.
During the Christmas season of the previous year, the Ukrainian military contacted Sean Gorman and his group at Zephr, a company that specializes in enhancing devices to resist GPS-signal interference. Zephr quickly dispatched six Android Pixel phones, preloaded with their software, to Ukraine, and in April, they began field testing near the frontlines in Donetsk.
During a discussion with Defense One, Gorman stated that the phones were secured to drones, placed in automobiles, and set up on fixed stands. They have also been performing controlled experiments using their own signal jammers, which allows them to determine the exact location.
The central objective was to ascertain whether standard consumer smartphones, collaborating within a network, could reveal the presence of an entity attempting to jam GPS location data. The researchers found that by analyzing the GPS reception from various phones, they could determine when one or more devices were being compromised.
Gorman indicated, "We are fundamentally harnessing the sensors integrated within the phone. The most advantageous sensor is the raw measurements from the global navigation satellite system (GNSS) that the device offers. This includes automatic gain control (AGC), Doppler sensor data, carrier phase, code phase, and additional information that cell phones gather about their distances from satellites, cell towers, and other network elements."
Manufacturers place these sensors within cell phones to enhance their performance, such as by locating the nearest cell tower. These measurements are vital for the GPS-processing software that enables phones to communicate the user's location. By analyzing data from a variety of phones, it is feasible to identify which devices may be facing security threats.
Gorman indicated that the backend computational AI we are utilizing, combined with the sophisticated processing of signals and software, allows for a wide range of functionalities. Rather than depending only on sensors or costly antenna arrays, there is a remarkable potential in networking phones to work together as a comprehensive distributed antenna system.
The investigations also highlighted new revelations about Russian electronic warfare.
Russia's actions in the Baltic Sea include the spoofing of GPS signals, resulting in receivers showing inaccurate location data. NATO officials have deemed this an unsafe condition for civilian aircraft. A common tactic employed against drones is GPS spoofing, which misguides the drone into believing it is located over an airport, compelling it to either land or retreat from areas of restricted airspace.
On the frontlines in Donetsk, Ukraine’s soldiers often report spoofing attacks aimed at their drones. But Gorman and his team found that much of this “spoofing” activity is actually just high-powered jamming attempts. Because those attempts are occurring in the same frequency bands as GPS or GNSS, they appear like satellite signals, effectively creating phantom or ghost satellites in places where they could not possibly exist and still provide signal, such as beneath the horizon.
Gorman described in a document provided to Defense One that the noise does not conform to the standard GNSS signal profile; however, it does include energy at the frequencies the receiver is investigating for satellite signals. The receiver's signal-processing algorithms utilize correlation techniques to identify and track these signals. The presence of a strong jamming signal can induce false correlations, resulting in the receiver mistakenly believing it is detecting satellites that are not genuinely visible.
The collective, now functioning under a contract with the Ukrainian government, is seeking to elevate their research efforts to not only identify cell phone jammer but also to triangulate their positions, thus allowing for effective avoidance or elimination strategies.
“The new techniques we are building 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 angle of arrival,” Gorman said in an email. “Each smartphone will detect the interference signal, log the last known position, and timestamp the reception, providing data points across the network. By aggregating and processing these signals centrally, the system will triangulate the jammer's position.”
The United States military is investing extensively in alternatives to GPS, known as alternative position, navigation, and timing, or Alt PNT, to support individuals, drones, and similar technologies in locating themselves. However, the returns on these investments have, in many instances, been less than satisfactory.
Gorman emphasized that the effectiveness of the system hinges on having an initial known position, which is nearly impossible to ascertain in the absence of GPS.
This networked approach is not designed to replace other, more expensive military systems that focus on detecting and locating jammers. Instead, it offers a solution that can be deployed quickly and at a lower cost for military forces like Ukraine and other organizations that could be affected by jamming activities, such as first responders. While it will not eliminate the need for developing alternative position, navigation, and timing methods, it has the potential to enhance their overall effectiveness.
Gorman remarked that there might be an entirely different way to conceptualize this issue. Rather than dedicating all resources to Alt PNT and GNSS resilience, which are certainly valuable, it may be beneficial to investigate how this situation has come to fruition. He underscored the significance of mapping and comprehending the area concerning the emitters, allowing us to avoid those regions and eliminate the emitters.