Study Of The Fast Factorized Back Projection Algorithm Applied To Ultra Wide Band Synthetic Aperture Radar

With good resolution and great foliage penetration capability, Ultra Wide BandSynthetic Aperture Radar (UWB SAR) has become a main research topic of SyntheticAperture Radar (SAR). Back Projection (BP) algorithm is suitable for UWB SARimaging for its advantages such as perfect focusing and perfect motion compensation.However, its application will be limited by the big computation load. The FastFactorized Back Projection (FFBP) algorithm, which substantially reduces thecomputational load, can improve the practicability of the BP algorithm. Sub-ImageFFBP (SIFFBP) algorithm, as one kind of FFBP algorithm, has a great applicationprospect in far distance and big scene imaging for its low memory consumption andeasy realization. Aiming at the far distance and big scene imaging application of theairborne UWB SAR, this paper lucubrate the SIFFBP Algorithm.The main achievements and contributions of the dissertation are as follows:1. An improved SIFFBP algorithm based on optimal regional partition is proposedby analyzing the regional division constraints. It provides a way to solve theacceleration-decline problem of the conventional SIFFBP algorithm when the SARsystem has a small integration angle. The proposal can evidently reduce thecomputational load when the integration angle is smaller than60degree or when thelength of the imaging region is much larger or smaller than the width.2. The theory of SIFFBP algorithm applied to non-linear aperture is studied. Afterrecommending the theory of Polar-FFBP (PFFBP) algorithm under non-linear flightgeometry, the theory of SIFFBP algorithm applied to non-linear apeture is studied, andthe optimal regional partition under non-linear aperture case is gained.3. The effects of flat surface assumption to SAR time-domain algorithms imagingquality are studied. This paper studies the effects of this assumption on time-domainimaging algorithms, points out that it leads to position offset problem in the case oflinear aperture, and it even leads to target defocusing problem in the case of non-linearaperture. The expression of position offset is given in this paper, as well as therestriction of the maximal offset of the non-linear aperture and the maximum elevationof the area in order to focus the targets.4. The SIFFBP algorithm which the terrain altitude error is corrected is proposed.After modifying the image model under flat surface assumption to rugged terrain circumstances, the method of SIFFBP algorithm combined with the Digital ElevationModel (DEM) is gained, and then the terrain altitude error corrected SIFFBP algorithmis proposed.A large amount of experiments based on simulative and real datas areaccomplished to show the significance of the study.