Passive Coherent Location With Unknown Transmitter States

This paper addresses the problem of passive coherent location (PCL) using a mobile transmitter with unknown state as an illuminator of opportunity. First, the necessary and sufficient conditions for local observability are derived using the Fisher information matrix (FIM). Second, a two-point track initialization approach, together with an efficient numerical search method, is proposed to initialize the target state as well as the transmitter state. Third, a recursive multitarget tracking algorithm with the proposed PCL system, in which the number of targets is unknown in the presence of measurement origin uncertainty, false alarms, and missed detections, is presented. The target state and the transmitter state are estimated in a sequential manner. In order to improve track continuity, a two-level gating technique is adopted in the data association phase of the proposed algorithm. Fourth, the posterior Cram $\acute{e}$rRao lower bound (PCRLB), with measurement origin uncertainty and transmitter state uncertainty, is derived to provide the optimal theoretical performance bound. Simulation results show the effectiveness of the proposed method.