Processing of COBRA FMCW SAR data

We present results from air-borne SAR campaigns using the FMCW SAR system COBRA operating at 35 GHz. Thanks to its large bandwidth the theoretical image resolution is below 10 cm in both the range and azimuth dimensions. Highly precise navigation data as well as very accurate synchronization of navigation and SAR data enables equally accurate absolute positioning. The SAR data were focused using a Frequency Scaling Algorithm (FSA) that accounts for the movement of the platform during the long ramp duration. The focusing chain integrates a two-step motion compensation scheme. The geometric and radiometric characteristics of the resulting single look complex (SLC) images were analyzed based on corner reflectors deployed within the test site. The scene was illuminated several times from two opposite directions in a standard strip-map mode. For each track, highly overlapping data segments were focused and geocoded individually. These products were subsequently mosaicked to generate a single geocoded image. Examples of change detection and moving target indication are also given.