High-resolution Isar Imaging And Three-dimensional Imaging Study

The Inverse Synthetic Aperture Radar (ISAR) is developing on the base of Synthetic Aperture Radar (SAR). ISAR is fixated and image for the moving targets, such as missile, satellite, airplane and ship. ISAR can provide an all-weather, day/night capability to generate high-resolution two-dimensional images of the targets for recognition over a long range, has played a more and more important role especially in space object detect and recognition. High resolution ISAR as one of the space object detect radar, which has a stand out strongpoint compared with general space object detect radar, represent the development way of space object detect radar. As the developing of ISAR, the request for imaging revolution is higher; at the same time, there are demands for three-dimensional ISAR imaging which can give more information. Following with developing trend of ISAR imaging, the high-revolution ISAR imaging arithmetic and the three-dimensional ISAR imaging arithmetic are researched in-depth.Work and innovations of this thesis contains:First establish and analyze the signal-processing mathematical model of ISAR system in detail, which can provide the theoretic foundation for chapter behind.In the field of range alignment, the norm-correlation method is employed to completely avoid the envelope drift and envelope jump caused by error accumulation, replacing the traditional neighbor-correlation and accumulated cross-correlation method; to further improve the alignment, a new sub-range-cell resolution range alignment method based on the phase information of echo is proposed.In the field of phase compensation, the chirp rate of the chirp component of cross-range signal caused by target's translation is accurately estimated; the method by global searching of ISAR parameter and the way by estimating the phase difference of border upon PRI is presented.The high-revolution ISAR imaging arithmetic can reduce the sidelobe and yawp; research on MUSIC, ARMA, ESPRIT super-resolution imaging technology is made to improve image quality, especially in the case of small segment of viewing angle.Based on the movement characteristic of spin target, a three-dimensional ISAR imaging for spin target by back projection algorithm is presented. The calculated results of the 3-D point spread function (PSF) of nonlinear motion 3D ISAR validate the theory analysis.An ISAR imaging algorithm for multiple targets based on Range History estimate is presented. With the image entropy criterion, the motion compensation to the echo data is implemented by means of the optimum estimation to the Range History of the target through the iteration operation. By use of the difference of motion parameter of multiple targets, it can separate the signal of one target from others in different conditions and image successfully.