Passive Coherent Location With Transmitter Location Uncertainty

In the passive coherent location(PCL)system,the third-party signal station,such as FM,mobile station is used as the transmitter of opportunity.Through the signal coherent processing of the direct wave and the target echo of the transmitter,the target is located passively.Due to the advantage of low cost,strong anti-interference capability and good stealth/anti-stealth,the PCL system plays an important role in air-defense early warning and other military applications.It is of great strategic significance for military defense and airspace security.This thesis focuses on the dynamic programming(DP)based low observable target tracking algorithm with the airborne PCL(APCL)system,where the location of transmitter is uncertainty.The contributions is as follows:In order to track low observable targets in heavy clutter with fixed transmitter PCL system,a dynamic programming method is proposed.The cost function in the DP is constructed using the measurements,and then is accumulated to find the target originated measurements by the track backtracking.According to the Extreme Value Theory,the threshold is derived,which reduces the probability of false track acceptance.The target state is estimated with a nonlinear filter from the measurements extracted by the DP technique.Simulation results show that the proposed method can track the target accurately and constantly in heavy clutter.Furthermore,with mobile transmitter PCL system,a dynamic programming state augmentation(DP-SA)method is proposed.First,taking the transmitter location uncertainty into account,the state transition region is established using error propagation theory.Secondly,the innovation covariance is modified online to reduce the effect of the transmitter location uncertainty.The state augmentation technique is invoked to estimate the target state and the transmitter state simultaneously.Simulation results show that the proposed method can effectively reduce the effects of the transmitter location uncertainty on the target tracking.Finally,the height parameterized method is proposed to estimate the three dimensional target state from two dimensional measurements with mobile transmitter PCL systems.The height range that the target may appears is divided into several subrange,each of them is assigned a matched filter with the corresponding weight.In each subrange,the state of the target and the transmitter are estimated simultaneously using the state augmentation.Then the height estimate is obtained by summing up the height estimates of all subrange.Simulation results verify the effectiveness of the proposal method.