Experiments with autofocus for strip map synthetic aperture radar data

In this paper we compare the resulting images using three autofocusing techniques and navigation data from measurements performed from a rooftop rail system with a C-band radar developed at FFI. We describe the system and its characteristics, and we apply the autofocusing techniques to images of a scene containing a corner reflector and other targets. The results show that all autofocusing techniques improve the quality of the images, and the methods using a single prominent point give better results than the more general phase gradient autofocus method. The experiments also show that the measured data can be used to reliably estimate the range displacements of the aperture over the flight path when a fixed point in the scene is used a reference.