Research Of Moving Target Detection Technology Based On FDA

Moving target detection has always been one of the most basic but most difficult research interests in the field of radar.Due to the complexity of the detection environment,such as the existence of strong clutter and what is more special is the presence of range ambiguous clutter in the main lobe of the radar beam,it puts forward a severe test to the traditional radar system,and the traditional radar system is also inadequate.In this paper,based on frequency diverse array(FDA)radar,the moving targets detection under three background conditions is studied: dim moving targets,strong homogeneous clutter,main lobe range ambiguous clutter.Compared with the traditional radar system,this paper not only proves that the new radar system can adapt well to the traditional radar signal detection method,but also solves the problem of the range ambiguous clutter of the main lobe which is difficult to be solved by the traditional radar system.The main research work carried out in this thesis can be summarized as follows:1.The beam characteristics of FDA are researched——time varying,range and angle dependence.For the beam cannot be focused due to its range angle coupling,various spot beam forming methods are studied,including: nonlinear frequency offset design,spot beam forming based on sub-array division,multi-frequency spot beam design and FDA-MIMO beam forming method.Spot beam design decouples the range and angle dimensions,it can locate the target in two dimensions accurately,this is impossible with conventional array radar.2.The detection of dim moving target based on FDA is researched.Firstly,this part considers the time-varying of FDA beam and analyzes its influence: cancel out the range dimensional direction of FDA and causes the angular beam to deviate from the actual position.Then,a combination of FDA and MIMO is proposed and analyzes the reason why FDA-MIMO can solve the problem.Finally,the traditional dim target detection algorithm(keystone + phase-coherent accumulation)is applied to FDA-MIMO radar,well-solving the problem of dim moving target detection based on FDA.3.The problem of moving target detection under the background of homogeneous clutter based on FDA is researched.This section considers two models:Multiple array elements transmit single antenna receive(FDA + single antenna)andmultiple array elements transmit array antenna receive(FDA-MIMO).Both modes adopt the method of MTI/MTD to suppress clutter,simulation results show that the two modes have good clutter suppression effect.For former mode,the effect of frequency offset on pulse pressure(matched filtering)was analyzed and the constraint condition of frequency offset is given.4.The detection of moving targets in the background of the main lobe range ambiguous clutter based on FDA is researched.This part considers the existence of multiple targets in the unambiguous detection area,at the same time,there are multiple clutter in the ambiguous region with the same angle and different range of the beam.First,applying SRDC is to compensate the main range value of echo and distinguish the ambiguous times,then applying multiple signal classification(MUSIC)algorithm to locate the target and clutter position,finally,using a linear constrained minimum variance(LCMV)beam former to suppress clutter.