Cross-Range Scaling Algorithm Based On ISAR Imaging

Inverse Synthetic Aperture Radar (ISAR) is a kind of high-resolution imaging radar, it can image for aircrafts, missiles, ships, celestial bodies, so it possesses important military and civilian value. ISAR adopts large bandwidth radar signal to obtain high range resolution images, the cross-range resolution of ISAR depends on both radar wavelength and rotating angle of target relative to radar-line-of-sight during the coherent accumulation. The former is known while the latter is difficult to determine especially in the case of non-cooperating target. The target track is always very complicated, so the rotating angle of imaging has great influences on ISAR images. During the period of imaging, different resolutions of two-dimensional images are not expected. Specific sampling points are chosen in order to obtain cross-range resolution the same as range resolution. It is a study topic on ISAR technology. This study has practical significance to furtherly gain true target images and implements radar target identification.The main contents of the thesis are to research how to get cross-range resolution of ISAR imaging, that is to say, the problem of ISAR cross-range scaling. Space position filtering and adaptive filtering algorithm are established to target moving track, get rid of error, which made from the meature of radar, and then compute the rotation angle and cross-range resolution. The contents are divided into the following four aspects:Firstly, the thesis researches on the fundamental of ISAR imaging technology, particularly the cross-range resolution of ISAR imaging and cross-range scaling method. And the paper starts by the track of moving target aspect, proposes the cross-range scaling method.Secondly, the thesis sets up the target moving model, building up the constant velocity model, constant acceleration model and maneuvering model of target moving.Thirdly, the thesis takes the road to the measured distance data, azimuth angle data and pitch angle data of narrow-band of ISAR, using space position filtering, the alpha-beta filtering, the alpha-beta-gamma filtering and Kalman filtering algorithm to estimates moving target track information.After the above work, it computes the whole rotation angle through the establishing trajectory, adding to the wavelength, confirms the cross-range resolution. Computer simulation is carried out to the researching tool of MATLAB, the simulation proves the correctness of cross-range scaling method, as well as compares the result of the various algorithms.