WEIGHTED LEAST SQUARE SAR AUTOFOCUSING TECHNIQUE (WLS).

The Weighted Least Squares (WLS) autofocus algorithm has been widely used in spotlight Synthetic Aperture Radar (SAR) for phase error estimation to compensate motion-induced blurs in the images. The WLS autofocus algorithm has proven to be a superior method for higher order autofocusing because it can be used to estimate all kinds of phase errors, no matter whether they are of low order, high order or random. Compared with other methods, the WLS estimation is optimal in the scene that it has the minimum variance of the estimated error. In this paper, a proposed PC-based software model of the WLS autofocus algorithm is introduced. Simulation results between blurred and focused images, or between the input phase error function and the estimated one carried out by calculating the root mean square (rms) value of the residual phase error, show significant removal of high-order phase errors and better removal of the low-order phase errors. Finally, a suggested Graphical User Interface (GUI) of the proposed algorithm for easier handling on PC-based equipment is introduced.