Dynamic Echo Simulation And Characteristic Analysis Of Sea Surface Targets

The corner reflector interference seriously affects the detection and recognition performance of the radar seeker for the sea surface target.In order to improve the ability of the radar seeker to recognize the target in the electromagnetic interference environment of the sea battlefield,it is necessary to analyze the characteristics of the echoes of both the corner reflector and the ship target.Due to the difficulty in obtaining the measured data and the high cost,the efficient and accurate simulation of the corner reflector interference and the target echo are prerequisites for the above work.Therefore,the paper performs echo simulation and characterization for several typical corner reflectors and ship targets.The specific work is as follows:Firstly,echo modeling and simulation were performed on the corner reflector and the ship target.By comparing several typical high-frequency calculation methods of RCS,the paper uses PO calculation method to simulate the full-polarization RCS of trihedral corner reflector,multi-unit combined corner reflector,array corner reflector and ship target.The multi-path scattering model of the target on the sea is used to calculate the coupled RCS.Then the two are added to obtain the static composite scattering total RCS.For the dynamic target of the sea surface,combined with the relative motion of the radar and the target and the 6-degree-of-freedom micro-motion model of the target,a dynamic echo simulation scheme is designed:based on the echo generation mechanism,the scheme calls the corresponding static composite scattering total field at different slow times,adds sea clutter echo,and gets the sea surface dynamic target echo.This method not only improves the computational efficiency of echo simulation,but also adds mocro-motion model to more accurately reflect the motion characteristics of moving targets at sea surface.Secondly,the echo characteristics of the corner reflector and the ship target are analyzed in the time domain,the frequency domain and the time-frequency domain respectively.The time domain mainly analyzes the one-dimensional range image distribution characteristics of the corner reflector and the ship target echo,and obtains the feature quantities of the one-dimensional range image: radial size,scattering symmetry,and number of scattering points.The power spectrum characteristics are analyzed in the frequency domain and the variation range of the power spectrum is obtained as the feature quantity.In the time-frequency domain,the time-frequency distribution characteristics of the micro-Doppler frequency are analyzed,and the total variation of the instantaneous micro-Doppler frequency is obtained.The variation laws of the above characteristic quantities with parameters is obtained by using theory combined with echo simulation.Finally,the Fisher criterion function is used to analyze the separability of the above-mentioned feature quantities of the corner reflector and the ship target.Finally,the echo characteristics of corner reflector and ship target in the polarization domain are analyzed.Krogager decomposition,Cameron decomposition and Cloude decomposition algorithm are used to polarize the polarization scattering matrix of the corner reflector and the ship target.It is found that the polarization scattering matrixs of corner reflector and the ship target are different on the scatterer structure.Based on this difference,the corresponding feature quantities are obtained.The variation laws of these feature quantities with various parameters are discussed,and the separability analysis of these feature quantities is carried out.Studies have shown that the extracted feature quantities can effectively distinguish corner reflector from ship target.