Parameter Extraction of Direct Wave for Passive Radar Using Suboptimal Nearest-Neighbor Approach

Under the trend of complex electromagnetic environment and development of new radar system, the direct wave of noncooperative radar is easily affected by clutter, multipath, and other noncooperative illuminators. These problems make it difficult for passive radar to extract the parameters of the direct wave. In this paper, a novel signal processing method using suboptimal nearest-neighbor (SNN) approach is proposed to acquire accurate parameters of direct wave. In this method, the parameter estimation of direct wave is converted to time-frequency data association. Firstly, the direct wave is processed with time-frequency analysis. Then, the SNN approach is applied to perform time-frequency data association and acquire the associated time-frequency line. Finally, the rough parameters are measured by calculating the positions of time-frequency line and accurate parameters are obtained by template matching with the known parameters. Simulation and experimental results verify the feasibility of the proposed method.