Challenges of Inertial and Integrated Navigation Systems in Synthetic Aperture Radar Application

Navigation errors in synthetic aperture radar (SAR) applications lead to phase errors in SAR echo signal and image quality degradation. Among different phase errors, zero and first order errors have no effect on image quality, while second and higher order terms are very important. The majority of second and higher order phase errors are due to initial alignment errors, and bias and random errors of inertial sensors. Integrated INS/GPS navigation systems are used for solving this problem. However, discontinuities in integrated navigation data lead to severe SAR image quality degradation. In this paper, the effect of different navigation approaches on SAR azimuth impulse response was studied and the importance of specially-designed algorithms to integrate INS and GPS was illustrated. Then, the proposed algorithm for navigation in SAR application was presented according to navigation errors behavior, and its benefit in azimuth impulse response, and imaging quality was illustrated. ‌‌