Flexible and Seamless Factorised Processor for Long-Range Mono- and Bistatic UAV-Borne SAR

This work describes a seamless and versatile factor-ized focusing procedure dedicated to large-scale, high-resolution mono- and bistatic Synthetic Aperture Radar (SAR) imaging. The algorithm deals with complex trajectories typical of Un-manned Aerial Vehicles (UAV). Efficiency and accuracy are two cornerstones of the algorithm to focus large-scale images at high resolution. Two scenarios are tackled. The first is a UAV-borne SAR with a short synthetic aperture and a wide field of view. We consider both monostatic and bistatic modes. In the latter case, with a still transmitter and a moving receiver. The second scenario is a stripmap UAV-borne SAR, with a receiver and transmitter moving with a fixed bistatic baseline in the bistatic mode. The entire processing scheme is based on a modified version of the Fast Factorized Back Projection (FFBP), exploiting an ad-hoc reference system in which the resolution is constant and the number of samples in the back-projection grid is minimal. The developed processor defines the best reference system and the strategies for the minimum computational cost. The theoretical performances of the entire workflow are derived as a rough number of complex operations required to focus an image. In addition, the results are supported by a numerical simulation comparing the different computational times of each algorithm in the ground-based-like UAV-borne bistatic SAR scenario.