Analysis and simulation of GPS/SINU integrated system for airborne SAR motion compensation

GPS/SINU integrated system for synthetic aperture radar motion compensation (SARMC) is studied. The mathematical model of the integrated system Kalman filter is described, the algorithm considers both long and short-term accuracy. Simulation results show that if the time interval of GPS updating SINU is smaller than the synthetic aperture time, the measurement error of the integrated system fluctuates rapidly, otherwise the measurement error is approximately linear increasing. While the former generates serious aberration, the latter mainly displaces the SAR cross-image. So the time interval of GPS updating SINU should be bigger than the synthetic aperture time in the practical SAR imaging phase. If the time interval of GPS updating SINU is bigger than the synthetic aperture time, the intentionally introduced sinusoidal position deviations on the magnitude of ten meters is estimated to linear increasing position errors whose relative variance in synthetic aperture time is within 5 cm. This will greatly facilitate the operation of SAR imaging processor.