2007, 29(12):44-47.
Abstract:
The phase gradient autofocus(PGA) algorithm has been proved to be an efficient autofocus method.It's good focusing performance is build on the base of fit statistical model and high signal-to-clutter ratio.But for the P band Ultra-Wideband Synthetic Aperture Radar(UWB SAR) image whose signal-to-clutter ratio is poor,the focusing result of PGA applied to it is not ideal.In this paper,we proposed the modified algorithm,which combined the contrast principle with tie traditional PGA algorithm.In the modified algorithm,the influence to the performance of PGA algorithm due to the low signal-to-clutter ratio of the degraded image will be effectively reduced.At the same time,this paper proposed the reference scatterer coregistration method,which can remove the shift(along the azimuth) distortion in the focused image that was caused by PGA algorithm.The algorithm proposed in this paper has been successfully used to focus some P band UWB SAR raw images data,and better-focused results were got as compared to the traditional PGA.