Evaluation of Trajectory Error Effects in BP Based Space Target ISAR Imaging

The space target imaging is important in the development of space technology. Due to the availability of trajectory information of the space targets and the arising of rapid parallel processing hardware, the back projection (BP) method has been applied to synthetic aperture radar (SAR) imaging and shows a number of advantages as compared with conventional Fourier-domain imaging algorithms. However, the practical processing shows that the insufficient accuracy of the trajectory information results in the degrading of the imaging results. On the other hand, the autofocusing algorithms for BP imaging are not well developed, which is a bottleneck for the application of BP imaging. Here, an analysis of the effect of trajectory errors on the space target imaging using microlocal technology is presented. Our analysis provides an explicit quantitative relationship between the trajectory errors of the space target and the positioning errors in the reconstructed images. The explicit form of the position errors for some typical trajectory errors is also presented. Numerical simulations demonstrate our theoretical findings. The measured position errors obtained from the reconstructed images are consistent with the analytic errors calculated by using the derived formulas. Our results will be used in the development of effective autofocusing methods for BP imaging.