Effective velocity estimation for space-borne SAR based on chirp scaling algorithm

Effective velocity is an important parameter for space-borne SAR imaging using chirp scaling algorithm. The precision of effective velocity estimation has strong impact on the quality of final SAR image. In this paper, two conventional effective velocity estimation methods and their intrinsic defects, such as inaccuracy and excessive dependence of satellite track parameters are firstly discussed and the reason why defects exist is also analyzed. Then a new algorithm is proposed for effective velocity estimation. The algorithm is based on iterative calculations and is independent of satellite track parameters; it can estimate effective velocity accurately by using variance of image as cost function. RADARSAT-1 image of Vancouver experimental data has been processed to demonstrate the effect of the proposed algorithm.