Research On Urban Target Detection Based On Multipath Exploitation

With the accelerated development of urbanization and intelligentization,the demands for detecting targets in urban areas are increasing with each passing day.Due to the traditional radars are designed for open areas,urban detection is a difficulty in the field of radar detection.There are dense people,cars,and buildings that can be targets need detected.At the same time,they may also become interferences and obstacles.If detected targets are in urban areas,buildings often block detect signals,which makes the targets obscured and results in detecting fails.Even if no shadowing occurs,these buildings will also make the radar signals reflect and refract,which produces lots of echoes propagate through multipaths.Recent studies have shown that multipath signals have potential to be utilized.Multipath signals can not only increase the accuracy of detection,also can increase the effective coverage of the radar because the echoes propagate via the multipath can cover the areas where the direct echoes can not cover.Therefore,the method based on multipath exploitation is an effective solution to the detection peoblem in urban areas.It has lots of theoretical significance and engineering value to study the detection methods based on multipath exploitaion in urban areas.The work of this thesis can be summarized as the following three parts:(1)Multipath propagation model of radar signals in urban scenes.Firstly,a multipath propagation model of radar signal with arbitrary specular reflection is given in a typical urban canyon scene.Based on the urban canyon scene,the multipath propagation model of radar signal in any building scene is given.The system equation and the observation equation based on multi-model ideas are proposed,which establishe a theoretical basis for detecting and tracking.(2)Targets localization based on multipath utilization.This thesis introduces the method of target positioning via radar briefly,and discusses the effects of multipath information in target location.It is pointed out that multipath information can provide auxiliary virtual detection sources,which can effectively reduce the requirement of radars.Then a specific method of using multipath information to locate the target is given.At the same time,the robustness of the method to clutter and false alarm in non-ideal conditions is also discussed.The accuracy of multipath positioning is discussed based on the estimation theory.(3)Targets tracking using multipath information.The urban canyon model is selected to analyze and realize target tracking using multipath information based on the enhanced particle filter and the proposed models.Then simulation results validate the improvement of tracking accuracy and effective coverage are given.At the same time,considering the situation of target maneuvering and realizing the tracking problem of maneuvering target based on the multi-model particle filtering method.Then the simulation of maneuvering target tracking results and analysis are given.