Transfer alignment from airplane GPS/MINS integrated system to SAR strapdown navigator

With the rapid development of modern science and technology, higher resolution images from an airborne synthetic aperture radar (SAR) are required, so, more accurate motion compensation needs to be applied to the radar returns to reduce image degradation which is caused by spurious motion of the antenna phase center (APC). The paper studies an improved SAR motion compensation system (SARMCS), which includes a master INS (inertial navigation system) and a GPS receiver located near the mass center of the aircraft, and a slave low cost strapdown IMU (inertial measurement unit) mounted on the antenna structure. A Kalman filter is an integral part of the SARMCS; it acts to continuously transfer alignment from a high accuracy GPS/MINS integrated navigation system to the less stable strapdown navigator. Simulation results show the absolute velocity error of the strapdown navigator is smaller than 0.3 m/s and the absolute attitude error of the strapdown navigator is smaller than 180 arcsec. So this SARMCS is effective