Simulation Research Based On ISAR Imaging Of Motion Target

With the development of information,the imaging of Radar Imaging technology is better.As an important branch of imaging radar,inverse synthetic aperture radar imaging research has always been an indispensable part of radar imaging research.Motion compensation and imaging algorithms has always been the key to ISAR imaging technology.It simulates and analyzes the inverse synthetic aperture radar imaging of motion target in this paper.The basic principle of ISAR imaging based on the scattering-center model is introduced.The Range Doppler algorithm and turntable imaging theory are introduced,and two high resolution signals which are LFM signal and SFW signal are also introduced.The echoes is simulated and the HRRP is theoretically derived for LFM signal and SFW signal.The fuzzy function of the two high resolution signals are discussed.Based on the LFM signal,the HRRP and ISAR imaging of aircraft target with different radial motion and rotation motion are discussed.The effects of target radial velocity and rotation velocity on the HRRP and ISAR imaging are analyzed.The simple target of scattering-center based on the SFW signal is analyzed to discussed the HRRP distortion by the radial motion.The necessity of translation compensation and rotation compensation is explained.For the aircraft target,the cross-correlation-motion compensation is analyzed based on LFM signal and SFW signal.The minimum entropy motion compensation is performed by SFW signal.The two rotational component compensation methods based on sharpness and phase difference analysis are simulated for the aircraft.To establish the target model,then,to calculate the scattered echo far-field data of the target with different frequency and different angle by using FEKO software.The two-dimensional Fourier transform is performed on the scattered echo data under small corner condition to reconstruct the target image.The results show that the image reconstruction based on the turntable target can apply the FFT reconstruction algorithm to the small angle of rotation.When the angle of rotation increases,the image defocused can not be reconstruction directly using the FFT algorithm.The imaging results of STFT for linear time-frequency distribution based on joint time-frequency distribution in the aircraft target imaging is compared with the imaging results of the Fourier transformation method.The results show that the complex motion of the target within the coherent processing time causes the Doppler frequency to change constantly,which can reduce the quality of the ISAR image.The traditional Fourier transform imaging method is not suitable for ISAR imaging of complex motion targets,and the joint time-frequency transform method can solve this problem.ISAR imaging is applied to the joint target.Plasma targets is imaged,and the HRRP of the plasma target is discussed.The time domain finite difference method(FDTD)is used to calculate the electromagnetic scattering of the target's ontology and the plasma target after high-speed motion.The state space method of the GTD model is used to extract the equivalent scattering-center position of the target,and the calculated equivalent scattering center is used to perform one-dimensional HRRP image in the range Doppler algorithm.The results show that,the inter-pulse motion of high-speed motion can not be neglected,which causes the motion compensation to be more difficult than low-speed compensation.