Research On Target Detection And Waveform Design Methods Based On Environment Awareness

With the development of modern radar and the increasing complexity of electromagnetic environment,the interaction between radar and environment becomes more and more important.In the concept of cognitive radar,environment perception and waveform design are the key to improve radar detection performance.This paper mainly studies the method of target detection and waveform design based on environmental perception.By sensing the clutter information in the environment and combining the prior knowledge of the target,the optimal detection transmitting waveform is designed,and the detector type is selected dynamically.The detection performance of the radar in the clutter environment is improved from both the transmitting and receiving ends at the same time.In addition,deceptive jamming is easy to produce,small power and difficult to confront in electromagnetic environment countermeasure,which is the research focus of jamming technology.In order to combat deceptive jamming,a genetic algorithm is proposed to generate orthogonal pc-lfm waveform,which can suppress the jamming energy in azimuth and distance direction simultaneously by superimposing random initial phase.The main contents of this paper are as follows:1)VITM-CFAR detector and ship target detection method in clutter environment.Based on the study and analysis of classical mean and ordered CFAR detectors,a CFAR Detector Based on change index and average rejection is proposed,which can dynamically select the window and type of the detector according to the change of clutter in the background window,and improve the detection performance in complex clutter environment.Based on the study of the classic ship target detection algorithm,a ship target detection method of inshore SAR image is proposed.After a series of preprocessing of the SAR image to be detected,the proposed two-dimensional VITM-CFAR detection window is used to detect the ship target on the image.Simulation experiments show that the proposed algorithm has good detection performance.2)The optimal waveform design based on clutter environment perception.This paper introduces the types and distribution characteristics of radar clutter environment,and proposes a waveform design method based on self optimization of clutter power spectral density.In this method,the maximum output signal to noise ratio of the receiver is taken as the criterion,and the clutter distribution information in the echo is fully utilized by the method of environmental perception.A phase iterative algorithm is used to synthesize the optimal transmitting waveforms suitable for the clutter environment.The simulation results show that the proposed algorithm can effectively improve the output SNR of the receiver and provide a good precondition for improving the target detection ability of the radar system.3)Based on PC-LFM stack random initial phase anti-interference waveform design.In this paper,two common radar signals,LFM signal and phase coding,are studied,and their Doppler characteristics and correlation performance are analyzed.On this basis,the time-domain waveforms and ambiguity functions of PC-LFM signals are studied,and the range resolution and orthogonality of the signals are analyzed.In order to combat deceptive jamming,the orthogonal PC-LFM waveform is generated by using genetic algorithm,and the orthogonal PC-LFM waveform with random initial phase superimposed in azimuth direction is proposed.The simulation results show that the waveform can suppress the jamming energy in two dimensions of distance and azimuth,and has a good ability of anti forwarding deceptive jamming.