A Study Of SAR/ISAR Imaging Based On Metric Optimization

SAR/ISAR imaging utilizes the moving relationship between radarand target to resolve high azimuth resolution. High range resolution isresolved by transmitting wide-band-width pulse singles. SAR/ISARimaging system is a coherent imaging system. The key of obtaining highresolution image is the maintenance of accurate coherent phases ofechoes. But in the processing of field SAR/ISAR imaging there arefactors such as the sway of radar or the approximation of imagingalgorithm or the non-cooperation of target that will change the phaserelationship between different echoes. This will blur the target image. Sothe attached error phases should be removed to maintain the coherentrelationship of different echoes.There are many methods to achieve the SAR/ISAR phase adjustment,and the optimization auto-focus algorithm is a promising method. Theaim of auto-focus is to obtain high resolution image by drawing out theattached error phases and removing them from the blurred image. Thekey of optimization auto-focus algorithm is the search of globaloptimization point in the phase space to estimate the attached error phases.Gradient descent method is a typical search technique.First in this paper, the principle of the optimization auto-focusalgorithm will be analyzed, and the performance of the optimizationobjective function in the phase space will be derived. The analysis will be...