Synthetic aperture radar imaging with motion estimation and autofocus

We introduce from first principles a synthetic aperture radar (SAR) imaging and target motion estimation method that is combined with compensation for radar platform trajectory perturbations. The main steps of the method are (a) segmentation of the data into properly calibrated small apertures, (b) motion or platform trajectory perturbation estimation using the Wigner transform and the ambiguity function of the data in a complementary way and (c) combination of small aperture estimates and construction of high-resolution images over wide apertures. The analysis provides quantitative criteria for implementing the aperture segmentation and the parameter estimation process. X-band persistent surveillance SAR is a specific application that is covered by our analysis. Detailed numerical simulations illustrate the robust applicability of the theory and validate the theoretical resolution analysis. (paper)