A Target Positioning Method without External Information Assistance for Airborne CSAR Imaging

Radar is the abbreviation of radio detection and ranging, so radar is by its basic nature a ranging instrument. If radar range measurements from multi-views can be exactly performed and assembled, then the multi-views positioning method based on the range equations can localize a common target from a set of Synthetic Aperture Radar (SAR) images to its true coordinates. It is worth noting that the distribution of these SAR images has a great impact on the performance of the positioning method. Circular SAR (CSAR) is a special mode of SAR systems, it has attracted much attention for its ability to obtain scatters’ wide-angle backscatter information and realize high-resolution imaging. On the one hand, the wide-angle observation capability is an advantage in the multi-view positioning method. On the other hand, the curved trajectory of the platform fits the bill perfectly. However, the distribution of the selected sub-aperture images influences the positioning results greatly. Based on the proposed error transfer model, we analyze and conclude a principle of selecting sub-aperture images. The conclusions were verified by processing a set of real- measured CSAR data.