Lithuania has introduced an open-source system to detect hostile drones by turning volunteers' smartphones into acoustic sensors. Participants place an unused Android phone near a window, where the installed app continuously analyses ambient sounds for the characteristic noise of drone engines. If multiple devices record the same signal simultaneously, the system can estimate the drone's location.
The project involves around 20 specialists from Lithuanian tech and security agencies, aiming to recruit 10,000 users and expand the network to the Baltic states and Poland. Future plans include incorporating audio from surveillance cameras and installing sensors on telecom towers.