Radar-Based UAV Swarm Surveillance Based on a Two-Stage Wave Path Difference Estimation Method

The numerous applications of unmanned aerial vehicles (UAVs) have caused them to receive growing interest worldwide. However, misused UAVs have caused significant public safety and privacy concerns. Therefore, developing an anti-UAV surveillance system is of paramount importance. In this paper, we propose a radar-based UAV swarm surveillance approach. A frequency estimation-based approach is used to obtain a coarse wave path difference estimate. Then, by combining the coarse estimate from the first stage with an estimate from the phase comparison method, a fine and unambiguous estimate of the wave path difference is derived. Through the solution of a system of nonlinear equations regarding the measured range and wave path difference, the proposed method is able to provide an unambiguous three-dimensional (3D) position estimate for a given UAV swarm. Once such 3D positions have been collected throughout an observation period, system tracks of the UAV swarm can be formed. With these tracks, a target object map (TOM) can be generated and handed over to an interceptor to counter the UAV swarm. Theoretical analyses of the accuracy of the estimation results and the restrictions of the proposed method are presented in detail. Several simulations are also carried out to evaluate the performance of the proposed method.