Abstract: Provided are two-dimensional autofocus methods in a synthetic aperture radar (SAR) system which include: (1) two-dimensional pulse pair product algorithm including shear PGA, eigenvector phase history (“EPH”), shear PGA/EPH); (2) two-dimensional optimization algorithms including parametric one-dimensional estimate/two-dimensional correction, parametric two dimensional estimate/two-dimensional correction, unconstrained two-dimensional nonparametric and constrained two-dimensional nonparametric methods; (3) a two-dimensional geometry filter algorithm; (4) a two-dimensional prominent point processing algorithm; (5) a one-dimensional phase estimate of higher order two dimensional phase errors; and, (6) a fast SHARP parametric autofocus algorithm.

Abstract: An along-track alignment and formatting system (ATAFS) formats synthetic aperture radar (SAR) data to align and format signals from scatterers in a scene to achieve an ideal data format in the along-track dimension in which such ideal data format leads to improved image quality of an image based on the SAR data and/or reduced computational burden for generating an image based on the SAR data. Two aspects of the ATAFS include: 1) the division of data stabilization into two distinct steps; and 2) the along-track (or slow-time) migration of signal support of scatterers as a function of their along-track location. A suite of SAR image formation algorithms use the ATAFS in conjunction with conventional signal processing stages to transform input coherent signal data into a complex image with image quality and geometric accuracy commensurate with the inherent information content of the input data.