A new method of motion error extraction from radar raw data for SAR motion compensation

Due to the presence of atmospheric turbulences, airborne SAR raw data may be affected by deviations of the platform from an ideal straight line. Additionally, being rather expensive, the inertial navigation system (IMS) and the global position system (GPS) do not always provide desired accuracy and reliability. This paper presents a solution for aircraft motion error extraction from radar raw data. Based on the derived model, the acceleration in line of sight (LOS) direction is separated into range space invariant and variant components. The main idea is to extract these components of the acceleration from radar raw data. Then the displacement of the platform in LOS direction can be extracted and compensated. In addition, since the system under consideration in this paper operates with a constant pulse repetition frequency (PRF), the motion error introduced by forward velocity variation should be considered. This paper also presents a solution for compensating this motion error. Finally, we present results on real data aimed at validating the proposed methods