Research On Moving Target Detection Method Of GEO Spaceborne Airborne Bistatic SAR

Geosynchronous(GEO)spaceborne-airborne bistatic Synthetic Aperture Radar(SAR)is a bistatic SAR system with GEO satellite as the transmitting station and airborne platform as the receiving station.The GEO spaceborne-airborne bistatic SAR system has the features of good stealth and flexible configuration,it has a broad application prospects in the field of remote sensing.Thesis focuses on motion characteristics and range model,clutter suppression and parameter estimation for GEO spaceborne-airborne bistatic SAR moving target detection,and the main research contents are as follows:1.The motion characteristics and range model of the GEO spaceborne-airborne bistatic SAR system are studied,the impact of earth rotation and target and airborne receiving station motion on propagation delay under long propagation delay is analyzed.The time delay under the "non-stop-and-go" assumption is derived,and numerical solutions,approximate solutions and expanded solutions are obtained,which establishing a theoretical foundation for subsequent research on methods.2.An improved Displaced Phase Center Antenna(DPCA)method is proposed,the phase relationship between channels of GEO spaceborne-airborne bistatic SAR system is derived.By distance envelope pre alignment,the impact of long transmission delay on the inter channel envelope registration is solved,and the clutter suppression is achieved.3.A method based on matrix rank-1 sparse decomposition of the GEO spaceborne-airborne bistatic SAR moving target detection is proposed.The method is performed by alternating direction multiplier method and combined with singular value shrinkage and negative gradient descent,and the function of moving target indication under this system is achieved.4.A two-step doppler parameter estimation method based on spectral processing is proposed.The doppler parameter estimation problem in the case of doppler center ambiguity under the GEO spaceborne-airborne bistatic SAR system is solved.By performing range spectrum inversion multiplication operation after delay conjugation multiplication,the decoupling effect and the estimation of doppler modulation frequency is achieved.and then by subband signal processing and phase compensation,the estimation of doppler centroid frequency without ambiguity is achieved.The proposed model and method are validated by theoretical analysis and simulation experiments.The results show that the above method can detect the moving target signal from clutter and estimate the signal doppler parameter under the GEO spaceborne-airborne bistatic SAR system.