Experimental Evaluation of a Low-Cost UAV-based System For Locating Ground Transmitters

Unmanned Aerial Vehicles (UAVs) are becoming an indispensable tool in civilian and military data-gathering and reconnaissance tasks, due to their ability to freely fly over a mission area and collect data. In this paper, we experimentally demonstrate how off-the-shelf Software-Defined Radio receivers can be used as part of a UAV payload, to create a cost-effective system to locate the origin of a radio transmitter. A uniform linear array of antennas is used to measure the angle-of-arrival of the signal, which is then combined with the GPS coordinates of the UAV and processed with an Unscented Kalman Filter algorithm to estimate the location of the transmitter. We demonstrate this system in field conditions, and show that the system can accurately estimate the angle-of-arrival. We demonstrate that a low-power handset can be located to within 100m from over 1.5km away within several minutes of flight. While our experiment is based around a search and rescue scenario, this localisation approach has wider applicability for wireless communications applications.