CLEAN technique for passive bistatic and multistatic SAR with GNSS transmitters

This paper presents the description and some examples of application of the CLEAN technique to passive SAR based on GNSS emissions, in order to extract the scattering centers in the achieved images and to increase the understanding of the imaged scene. Two different operative scenarios are considered: the bistatic case, involving a single GNSS transmitter and a ground-based receiver, and the multistatic case, achieved by considering the non-coherent combination of the BSAR images obtained by multiple, spatially separated satellites. The effectiveness of the technique in extracting the point scatterers´ returns in the bi/multi-static images is proved against simulated and real datasets. Moreover, the inherent capability of rejection of the ghost scatterers arising in the multistatic images from close scattering centers is shown. The application of the proposed technique allows the proper extraction of the amount of information of the observed area.