Research Of GEO Spaceborne/airborne Bistatic SAR GMTI And Imaging Technology

In this thesis, the technologies of moving targets detection and imaging bySpaceborne-Airborne bistatic SAR system which based on Geosynchronous Satellitesystem are researched. This field is the emerging hot spot of research directionabout SAR in recent years. Firstly, the work mode of GEO Spaceborne-Airbornebistatic SAR is studied, a work mode of this bistatic SAR system which based onsliding spotlight is proposed, further the GEO SA-Bi SAR imaging model isconstructed in the work mode of sliding spotlight, then the system features andparameters are analyzed in detail. Using the maximum estimation method and theimage offset method estimate the moving target Doppler center frequency andDoppler rate respectively, on the basis of this the phase center offset antenna (DPCA)and along-track interferometry (ATI) method are applicated, with combination ofRange-Doppler Algorithm (RDA), the detection and imaging of moving targets thaton the ground can be achieved. The main contents are as follows:1) To overcome the work mode of GEO SA-BiSAR system and the imagingfeatures problem in this work mode, the sliding spotlight work mode is proposed.The resolution expression of GEO SA-BiSAR system in the case of sliding spotlightmode is derived, and the resolution characteristic of the system is analyzed. Basedon transmitter and receiver operating speed ratio and the receiving beam groundmoving speed-the receiver speed ratio to measure system resolution dependence onoperating parameters, the feasibility of the system is primary demonstrated.2) Considering the GEO SA-BiSAR system is the motion variable bistaticsystem，the monostatic and the general bistatic imaging algorithm is no longerapplicable，in this paper, using the Back Projection algorithm to process the rangecompressed signal for the imaging by response position according to the time delayin the echo area. The experimental results show that under motion variable bistaticsystem, improved CS algorithm and BP algorithm both have good imaging results.3) To overcome the imaging problem cause by different orbits of satellite andairplane, a motion variable Bi-SAR model of different height, location and velocity,then use bias phase center antenna (DPCA) technology, and along the trailsinterference (ATI) method, with combination of Range-Doppler algorithm (RDA) toachieve the detection and imaging of moving targets that on the ground. Based onthe analysis of simulation results of the moving target imaging in this system,itshows that the effectiveness of the proposed algorithm in this thesis.