Generalized autofocus scheme for multi-mode airborne SAR systems

According to the characteristics of different airborne synthetic aperture radar (SAR) imaging modes, a generalized sub-aperture autofocus scheme based on Doppler rate (DR) estimation is presented, which can well integrate into the existing multi-mode SAR imaging processor. In this scheme, suitable strategies for sub-aperture segmentation and Doppler rate errors (DREs) estimation are generated. Its effectiveness is validated by three airborne real data sets with different imaging modes, collected by the same C-band experimental system.