Research On Synthetic Aperture Radar Imaging And Motion Compensation

Synthetic aperture radar is a kind of radar which has an advantage of ability of high resolution in both distance dimension and azimuth dimension. It is widely used in many areas of military and civilian. SAR is typically used to scan or detect a scene. We can separate SAR just by moving platform, it can be devided to airborne SAR, spaceborne SAR and missile-borne SAR. The main content of this paper consists of two aspects. SAR imaging of large squint-case and SAR imaging motion compensation.The main contents are as follows:1. At first, the chirp signal and pulse compression principle are described. A side-looking SAR imaging model is setted as an example to analyze the reason that SAR imaging can have high resolution in both distance dimension and azimuth dimension. And two basic SAR imaging algorithm are introduced.2. Large squint SAR imaging is analyzed, including squint increasing having an impact on distance migration and distance bending. High level distan ce bending impact on SAR imaging is analyzed, then,X-band cubic phase correction method is given. As a special model for large squint SAR imaging, missile-borne SAR moving as a parabolic trajectory is analyzed. The moving is decomposed in each direction o f the speed and acceleration, and the impact of each part is derived. The derivation of correction method is given and proved by simulation.3. SAR motion compensationa algorithm is researched, SAR model error motion is analyzed. And optimum contrast autofocus algorithm(COA) is studied. Two commonly used search algorithm,advance and retreat method and golden section, are compared, golden section search range set by the man-made may be too small. This problem is solved, sub-block estimation methods is proposed and proved by simulation. At last, Doppler frequency estimation is used on the measured data, and the effectiveness of the algorithm is proved.