Russian Military Drones: Old Android Smartphones Can Sense Them Arriving

A Lithuanian startup has developed an Android application capable of transforming thousands of smartphones into a listening network against Shahed drones, the attack aircraft used by Russia in its invasion of Ukraine.

According to Lithuanian National Radio and Television, the system utilizes an algorithm to isolate the acoustic signature of the drones from environmental noise and signal their approximate location on a shared public map. The app is reserved for verified users and, if installed on a sufficient number of devices, allows for the estimation of the trajectory and flight direction of incoming drones. The goal is to timely alert both the civilian population and the armed forces before the ordnance reaches its target. The system is expected to be more accurate than past acoustic detectors precisely because it relies on advanced algorithms and thousands of sensors managed by verified users.

Old Android Smartphones Can Become a Weapon Against Shahed Drones

The Shahed drones measure between 2.4 and 3.7 meters in length, with a wingspan of about 2.4 meters: compact dimensions and lightweight materials that reduce the equivalent radar cross-section. Traditional radars can still intercept them, but the low cruising altitude combined with their reduced speed generates too many false positives, often confused with flocks of birds. These limitations make it difficult to isolate a real target from background noise until the drone is already near the target.

However, the low flight altitude works in favor of ground observers: the roar of the piston engine of these aircraft can be perceived from a distance, and it is on this principle that the new system is based. Its functioning recalls the mirrors and acoustic locators used by armies during World War I, when huge concrete dishes pointed skyward, or more manageable metal horn arrays, were employed by trained personnel to capture the low-frequency sound of incoming engines, in the absence of radar.

Shahed drones remain a threat primarily because of their low cost compared to more sophisticated missile systems, allowing Russia to launch them in numerous swarms to saturate Ukrainian air defenses. However, once detected far from the target, the older propeller models are vulnerable: reports indicate that even shooters aboard 50-year-old single-engine training aircraft, armed with shotgun or assault rifles, can shoot them down with a fair chance of success.

The crowdsourced acoustic system does not replace radars but can integrate them: thousands of sensors managed by verified users and analyzed by dedicated algorithms provide an additional data source to confirm whether a detected target is indeed a drone or just a false alarm caused by birds. The Lithuanian initiative is part of a broader effort of low-cost countermeasures against Shahed drones, which includes the requirement for Starlink users in Ukraine to register their terminals, to prevent Russia from using them to guide drones, as well as experimental systems like microwave guns for drone swarms and portable anti-drone lasers.