Application Of Overlapped Sub-aperture Algorithm (OSA) In High Resolution SAR Imaging

Synthetic aperture radar (SAR) is a new type of high resolution imaging radar. It acquires high range resolution and high azimuth resolution by means of combining the principle of synthetic aperture and pulse compression techniques. This paper analyzes the principle of Overlapped Sub-aperture Algorithm(OSA), and presents a method for processing strip-map SAR data by using OSA combined with Polar-Format processing Algorithm(PFA).Chapter 1 reviews the history, present situation and main trend of SAR, whereafter describes its characteristic and applied domain. Chapter 2 demonstrates the theory of Linearity Frequency Modulation, and then studies the imaging algorithm of basic Range-Doppler Algorithm and Chirp-Scaling Algorithm. The computer simulation of point target are presented.Chapter 3 makes comprehensive research into PFA(polar format algorithm) which is widely used in spotlight SAR imaging processing, and presents the resolution of processed images. In Chapter 4, the principle and implementation method of Overlapped Sub-aperture Algorithm(OSA) is described in detail. By using OSA, the system errors resulting from deramp-processing of SAR data are reduced. Computer simulation indicates that the algorithm is feasible and effective.Chapter 5 presents a method of improving the imaging resolution of PFA by using OSA to compensate the system errors resulting from deramp-processing. Chapter 6 discusses the relation between spotlight SAR and stripmap SAR, and presents a method for processing stripmap SAR data by using OSA. This Chapter also demonstrates the principle of PGA, and describes a method of combining OSA with PGA. The results of SAR raw data imaging demonstrate the feasibility of this method.Chapter 7 summarizes the whole work of this thesis and points out the problems to be solved in the future.