The Influence Of Space Adjacent Targets To Radar Detection And Resolution

The radar detection and resolution in the spatial Multi-targets have always been the research hotspots and difficulties in all the countries,and the research in the space adjacent targets is especially attached great importance.In the range dimension,the detection and resolution become difficulty due to the echo impact from adjacent targets.For example,the side-lobe of large target may mask the main-lobe of small target.Consequently,the small target cannot be detected and hence degrade the detection performance of radar.In the angular dimension,there can exist more than one target in one resolution cell of the mono-pulse radar main beam,this also can result in great deviation of target glint.All of these have serious impacts for the consequent radar data processing.Hence,it's very necessary to make some research on the detection and resolution in the presence of adjacent targets.As the problems mentioned above,in this thesis,we have proposed two techniques: in the range dimension proposed successive CFAR detection method based on Clean theory;in the angle dimension,proposed target tracking filtering algorithm based on multi-target existence decision.The simulation reveals that the proposed approaches can improve the detection?resolution and tracking performance of targets of interest in adjacent target disturbance.The main content in this thesis contains three parts as follows:Firstly,the influential aspects mechanism of adjacent targets on radar resolution cell is analyzed.In the range dimension,we derive the radar receiving signal expression of a single target and two targets,as well as more targets by using common linear frequencies modulation signal;In the angle dimension,we analyzed the mechanism of angular glint,all research shows that the adjacent target may cause the bigger angle error and measurement combination,resulting in bad effects on the sequent tracking and association.Secondly,Aiming to solve the target making problem of the tradition CFAR detection algorithm,we have studied the basic principle of CFAR detection in radar target detection.The detection probability is derived mathematically.The detection performance of CFAR detector in the presence of adjacent targets is analyzed.Combined with image processing commonly used Clean algorithm,a successive detection method based on Clean theory is proposed.Multiple-targets can be detected and resolved one by one.Simulation results show that the proposed method is effective.Finally,we research the problem of angle resolution and propose target tracking filtering algorithm based on multi-target existence decision.We also research the expression ratio of single and multiple pulses,and derive the difference mathematically,and point out that it can be used as a criterion to judge the existence of multiple-target.By using the decision results,we proposed the target tracking filtering algorithm.This method can divided into two steps: first is process noise correction,to let Kalman filter prefer prediction more instead of measurement if the decision of multiple-target is true;second is realization of a new merged measurement weighted by the prediction value and the real measured value.The advantage of this method is that full consideration of the effect of angular glint and target motion characteristics.The simulation is based on two targets related to of the parallel and cross motion,and using the nearest neighbor algorithm and Kalman filter,the validity of the method is verified.