Research On Application Of Clutter Suppression Technology And Real Data Analysis

The real clutter is very different from the ideal clutter model.In this thesis,based on the real data of radar,the clutter characteristics and clutter suppression techniques are analyzed.This thesis also deals with the design of clutter suppression techniques in engineering implementation for some model radar.The main works are as follows:1.The character of the clutter is studied.Firstly,The basic statistical characteristics are introduced,and the statistical distribution function of clutter power spectrum and amplitude distribution are given.Secondly,the causes of second-trip echo and theamplitude,correlation and spectrum of second-trip echo are analyzed in detail.Through processing real data,the simulation results are verified.Research indicates that the amplitude and correlation of second-trip echo fluctuate greatly between pulses,and the number of frequency components is the same as the number of pulse repetition frequencies.Thirdly,the characteristics of angel clutter are analyzed based on the real data of radar.Research indicates that the angel clutter moves around the vicinity of radar and moves in the same direction with the wind.Also,it's doppler frequency range is fixed.2.The clutter suppression technique is researched.Firstly,in terms of frequency domain filtering,MTI and MTD technique are studied.Two optimized design methods of MTI filters,the prediction error method and zero point distribution method,are analyzed.Also,three methods of AMTI,shifting center frequency method,weight coefficient library method and N-channel selection method are compared based on the real data of radar.Research indicates that the N-channel selection method,which does not require frequency measurement,is simple to implement and can achieve good clutter suppression at a lower filtering order.In MTD technique research,MTI cascade FFT filter group and point doppler filter group are introduced.By improving the design of point doppler filter group,the side lobe of the filters have been reduced.Real data processing results show that improved point doppler filter group has good performance.Secondly,according to the amplitude characteristics of the second-trip echo,two suppression methods are proposed.Real data processing results show that both methods can suppress second-trip echo well.Thirdly,according to the doppler frequency range of angel clutter,angel clutter suppression method is proposed.Real data processing results show that the proposed method can suppress angel clutter well.3.Engineering implement of clutter suppression technique is completed.Firstly,the overall design of the radar signal processor and the chips of FPGA and QDR are introduced.Secondly,the design and realization of adaptive clutter suppression,including radar clutter map,clutter contour map and MTI,are introduced in detail.Modelsim simulation results and ILA debugging results indicate that the design is feasible.