Detection And Imaging Of Moving Target For Cooperative Sar Between High-Orbit And Low-Orbit Satellites

Geosynchronous orbit(GEO)SAR has unique advantages in low-altitude small targets and ground moving targets detection because of its wide illuminable area,long coherent accumulation time,and difficulty in being occluded by ground objects.This thesis adopts the high and low-orbit system which the geosynchronous orbit SAR satellite is used as the transmitter and low-orbit satellite(LEO)as the receiver.The research on high-low orbit SAR moving target echo construction,moving target detection and imaging technology under this heterogeneous platform is carried out.The main tasks of the model including the distance migration correction and motion target parameter estimation are as follows:1.The geometric model of target imaging under high and low orbit heterogeneous platform is studied.According to the moving target trajectory,the echo model of moving target in high and low orbital coordinate system is derived.The range migration characteristics and Doppler broadening characteristics of the target are analyzed.A signal model suitable for high-low orbit SAR moving target detection and imaging is established.2.Aiming at the ground moving target,a method of moving target detection and imaging which combining joint subaperture cancellation and second-order Keystone transform is proposed.The single-channel sub-aperture cancellation technique is used to suppress the clutter and estimate the motion parameters of the moving target.Then,the second-order Keystone transform algorithm is used to correct the distance migration existing in the coherent accumulation of the ground target,re-image the moving target.Furthermore we analyze the imaging performance of moving target.Finally,the simulation experiment is carried out with the ground scene data and the simulated moving target data.The simulated moving target imaging experimental results verify the effectiveness of the proposed method.3.Aiming at low-altitude fast moving targets,a method of moving target detection and imaging which combining joint subaperture cancellation and KTCPF transformation is proposed.The single-channel sub-aperture method is used to cancel the ground clutter,and the motion parameters are estimated according to the positional offset of the moving target in the front and rear aperture images.Then the KTCPF transform is used to reimage the fast moving target.The simulated moving target imaging experiments verify the effectiveness of the proposed method.4.The geometric model and echo model of multi-channel SAR under high and low orbit heterogeneous systems are established.The space-time adaptive processing algorithm of data Doppler domain is introduced to suppress the ground clutter and coherent accumulation to improve the output signal.The moving target is finally detected by the constant false alarm processing algorithm.The point target simulation experiment verifies the effectiveness of the multi-channel STAP processing method under high and low orbit platforms.