Passive bistatic SAR with GNSS transmitter and a stationary receiver

This thesis is dedicated to the special class of bistatic SAR, where the transmitter is a Global Navigation Satellite System (GNSS) and receiver is fixed on the ground. Such a kind of geometry is suited for ground deformation monitoring. The employment of such a navigation satellite brings many advantages, such as shorter satellite revisit time (8-9 days) compared to imaging radar such as Envisat (35days). Moreover, due to large number of satellites deployed (at least 4 satellites could be seen at any time), persistent monitoring of a given area can be achieved from multiple angles simultaneously. This thesis presents research results on the imaging capability of SS-BSAR with GNSS and a stationary receiver. Firstly, the system is outlined and the reason of selecting GNSS as transmitter of opportunity is justified. The power budget and resolution were then analyzed. The end to end signal processing, from received raw data leading to SS-BSAR image, is described. Four experimental data sets acquired at different imaging scenarios are used to test our system hardware and signal processing algorithms mentioned below. It can be seen from the obtained images and associated analysis that such a system has the capability of real scene imaging

A Fourier-Based Image Formation Algorithm for Geo-Stationary GNSS-Based Bistatic Forward-Looking Synthetic Aperture Radar

A Geo-Stationary GNSS-based Bistatic Forward-Looking Synthetic Aperture Radar (GeoSta-GNSS-BFLSAR) system is a particular kind of passive bistatic SAR system. In this system, a geo-stationary GNSS is used as the transmitter, while the receiver is deployed on a moving aircraft, which travels towards a target in a straight line. It is expected that such a radar system has potential for self-landing, self-navigation and battlefield information acquisition applications, etc. Up to now, little information from a research perspective can be found about GeoSta-GNSS-BFLSAR systems. To address this information gap, this paper proposes a preliminary image formation algorithm for GeoSta-GNSS-BFLSAR. The full details of the mathematical derivation are given. It is highlighted that, to overcome the long dwell time and spatial variance of GeoSta-GNSS-BFLSAR, a modified migration correction factor must be designed. In addition, the system performances and technical limitations of GeoSta-GNSS-BFLSAR such as focusing depth and spatial resolution are analytically discussed. In the end, a set of simulations including the image formation algorithm, focusing depth and spatial resolution were conducted for verification. It is demonstrated that the focusing performances of the proposed algorithm have a high level of similarity with the theoretical counterparts. This article thus proves the feasibility of GeoSta-GNSS-BFLSAR systems from a simulation level and establishes a foundation for the real applications of such a radar scheme in the future