Synthetic Aperture Radar Autofocus Based on a Bilinear Model

Synthetic-aperture radar autofocus by maximizing sharpness.

To focus a synthetic-aperture radar image that is suffering from phase errors, a phase-error estimate is found that, when it is applied, maximizes the sharpness of the image. Closed-form expressions are derived for the gradients of a sharpness metric with respect to phase-error parameters, including both a point-by-point (nonparametric) phase function and coefficients of a polynomial expansion....

Backprojection Autofocus for Synthetic Aperture Radar

In synthetic aperture radar (SAR), many adverse conditions may cause errors in the raw phase-history data. Autofocus methods are commonly used in SAR to mitigate the effects of these problems. Over the years, many types of autofocus have algorithms have been created, however, each has implicit assumptions restricting their use. The backprojection image formation algorithm places few restriction...

A fast autofocus algorithm for synthetic aperture radar processing

Synthetic Aperture Radar ( S A R ) has become a valuable instrument with applications in reconnaissance and remote sensing. High resolution SAR imaging requires the motion of the radar platform to be known very accurately. Otherwise phase errors are induced in the processing of the raw S A R data, and bad focusing results. In particular, a constant error in the measured along track velocity or ...

Autofocus for inverse synthetic aperture radar (ISAR) imaging

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) preliminary motion estimation from the data using the Wigner transform and the ambiguity function...