Using Small Unmanned Aerial Systems (UASs) Equipped with Miniaturized Synthetic Doppler Receivers to Geolocate Radio Frequency (RF) Emitters

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) has developed a technique for geolocating radio frequency (RF) emitters using multiple, cooperating small, hand-launchable unmanned aerial systems (UASs). Each aircraft has an RF sensor that measures the phase difference between multiple, rapidly-switched onboard antennas to derive line-of-bearing (LOB). The LOB estimations from each aircraft are shared among all UASs and fused using onboard Kalman filters to obtain geolocation of the target emitter. These UASs operate fully autonomously with no human-in-the-loop required for either decision-making or flight control. The basic components of this concept, from sensor development to UAS autonomous behaviors, were demonstrated in flight at the Tactical Network Topology (TNT) experiment in August 2007.