Uncompensated phase errors lead to quality degradation of images obtained by synthetic aperture radars (SAR). This effect is especially critical for systems with high spatial resolution. A novel approach to estimating residual phase errors in stripmap SAR signals is suggested. The idea of the method is to estimate the local quadratic phase errors on short time intervals with the subsequent reconstruction of the unknown phase error on the time intervals of arbitrary length. The map-drift autofocus (MDA) algorithm is used for the local estimation. The performance of the proposed method is demonstrated with real radar data examples.

Local-Quadratic Map-Drift Autofocus for Synthetic Aperture Radars