Automatic positioning of UAVs to optimize TDOA geolocation performance

Unmanned aerial vehicles (UAVs) have proved extremely useful for a number of important tasks such as surveillance, remote sensing, and geolocation of radio frequency (RF) transmitters. Typically UAVs fly pre-programmed flight paths, or they allow for limited flight path changes via ground station controllers. However, it is difficult for ground station controllers to position UAVs in a manner that optimizes geolocation performance. This paper explores the problem of automatically repositioning UAV assets to optimize geolocation accuracy via time difference of arrival (TDOA) methods. First, we determine the geolocation accuracy that can be achieved for various scenarios and the TDOA timing accuracy needed. Second, we describe an algorithm to determine the quality of each TDOA measurement. Signal data corrupted by propagation effects and co-channel interference is used to validate the approach. Third, a path-planning algorithm for repositioning the UAVs to optimize geolocation accuracy is presented. Finally, some results using field test data are presented.