Mainline, a Lithuanian startup, has launched an open-source drone detection system called Drone Rada that crowdsources acoustic data from volunteers' Android phones to identify Shahed-type drone threats. Founder Audrius Zujus explained that unused smartphones placed near windows continuously monitor ambient sounds for specific low-frequency engine signatures, creating a distributed sensor network for national security.

The system works by having verified volunteers run an app that analyzes environmental audio for characteristic drone sounds. When multiple nearby devices detect matching acoustic signatures, algorithms triangulate the object's possible location. The initiative combines a monitoring platform with an interactive public map and a dedicated sensor application, currently involving 20 specialists and partners from the Lithuanian Artificial Intelligence Association and Baltic Institute of Technology.

Organizers aim to recruit 10,000 active users across the Baltic states and Poland, potentially expanding to include audio from surveillance cameras and sensors on telecommunications towers. The team is discussing cooperation with major mobile network operators to broaden coverage. Privacy remains paramount, with the system designed to minimize data collection while maintaining detection accuracy.

This represents a novel approach to civic defense infrastructure, leveraging existing consumer devices as distributed sensors rather than expensive dedicated hardware.