A modular localization system combining passive RF detection and passive radar

This paper presents a completely passive system for detection and localization of small aircraft and UAVs. The system makes use of the fact that almost any such target emits some kind of RF emission, either by active transmissions or by passive reflection of other sources. Active transmissions can for example be caused by telemetry or video downlinks to a remote control or some kind of unintended emission like a mobile phone carried by a passenger. These transmissions can be identified by means of passive detection. At the same time, passive reflections of signals radiated by illuminators of opportunity like FM radio stations can be used to build a multistatic passive radar.