Navigation and SAR auto-focusing based on the phase gradient approach

Synthetic Aperture Radar (SAR) equipment is an all-weather radar imaging system that can be used to create high resolution images of the scene by utilising the movement of the flying platform. It is therefore essential to accurately estimate the platform's trajectory in order to get good and focused images. Recently, both real time applications and smaller and cheaper platforms have been considered. This, in turn, leads to unfocused images since cheaper platforms, in general, have navigation systems with poorer performance. At the same time the radar data contain information about the platform's motion that can be used to estimate the trajectory and get more focused images. Here, a method of utilising the phase gradient of the SAR data in a sensor fusion framework is presented. The method is illustrated on a simulated example with promising results. At the end a discussion about the obtained results and future work is covered.