Long integration fine resolution SAR image formation

To perform fine resolution SAR imaging, the radar is required to image the area of interest for a long period of time. In this paper, the signal processing aspects of processing such SAR data is described. The signal processing challenges are to estimate the large motion errors contributed by the long imaging time and to limit the phase errors due to approximation in the signal modeling for fine resolution image formation. This paper presents the implementation of a sub-spot polar format technique with autofocus, to process data collected with long integration time. The sub-spot technique developed produced sub-spot images of the radar footprint. The full SAR image is formed by mosaicing the individual sub-spots. This technique allows the formation of a large scene image at fine resolution while utilizing the efficient polar format algorithm (PFA).