Motion compensation for ASTOR long range SAR

The United Kingdom Ministry of Defence is conducting a long range synthetic aperture radar (SAR) technology demonstrator programme (TDP) in support of their airborne stand-off radar programme. A major goal is to develop a high-resolution airborne SAR with both strip map and spotlight modes. To attain the image quality objectives of the project, it is essential that very accurate motion compensation be applied to the radar returns to reduce image degradation, caused by spurious antenna phase center motion, to acceptable levels. The SAR motion compensation system (SARMC) includes a master inertial navigation system located near the center of mass of the host aircraft and a slaved strapdown inertial measurement unit mounted on the back of the radar antenna, as well as Doppler velocity and barometric and radar altimeters. The performance of the SARMC has been evaluated both by analysis and computer simulation. These evaluations accounted for all major system error sources, including errors associated with sensors, transfer alignment, and computation, with the system operating in an environment of moderate atmospheric turbulence. Results from these evaluations are presented