Leonardo US Cyber and Security Solutions is rolling out SignalTrace, a sensor suite that adds Bluetooth, Wi‑Fi and RFID detection to existing automatic license‑plate readers. The devices capture emissions from smartphones, AirPods, smartwatches and other wearables, creating a searchable database of nearby electronic signatures. Police could use the system to locate suspects traveling together or to monitor protest crowds. City fleets are early adopters.

The sensors pair each signal with the visual snapshot taken by the ALPR camera, forming a digital fingerprint that links a device to a vehicle. Leonardo claims the software never decrypts content and that data is released only on law‑enforcement request, though no warrant requirement is mentioned. Existing deployments span nearly 4,000 customers across 25 countries.

Civil‑rights groups warn that a private firm holding real‑time location data without oversight could spark legal challenges. Earlier license‑plate networks have already been used to track protest activity in more than half the states, according to the EFF. SignalTrace therefore extends surveillance from cars to personal devices, raising the stakes for privacy advocates. The move could reshape public‑space monitoring norms.