用于SAR运动补偿的DGPS/SINS组合系统研究

DGPS/SINS INTEGRATED SYSTEM USED IN SAR MOTION COMPENSATION

使用考虑位置误差相关项的伪距率观测模型 ,研究了用于合成孔径雷达运动补偿的差分 GPS/ SINS伪距率组合系统。结果表明 ,组合系统的长期位置精度能达到 1 m左右。 GPS数据更新率低于 INS,在 GPS测量时间间隔内 ,组合系统的性能仅由 INS决定。虽然 INS误差随时间积累 ,在 GPS数据更新率为 1 s的情况下 ,即使采用中等精度的惯性仪表 ,其相对位置精度为厘米级 (这里相对位置精度指组合系统在 GPS测量时间间隔内位置误差的变化范围 )

Nowadays higher resolution image from an airborne Synthetic Aperture Radar (SAR) is needed in both civil and military usage, so more accurate motion compensation should be applied to the radar returns to reduce image degradation caused by spurious motion of antenna phase center (APC). As Global Positioning System (GPS) became practical usage, the SARMCS using the information of GPS has received increasing attention. The main aim using GPS/INS integrated system in navigation is to improve long term accuracy. For SAR motion compensation, both long term accuracy and short term accuracy are important. DGPS technique can dramatically improve the precision of GPS. DGPS/SINS integrated system for SAR motion compensation is studied in this paper. First, the principle of DGPS/SINS pseudo range and pseudo range rate integrated system is described, then the state equations and precise measurement model concerning position error is given, and finally the algorithm of integrated system Kalman filter and error propagation of INS are newly described. Simulation results show that even if middle accuracy INS instrument is used, the long term position error of integrated system is about 1m and relative change of position error in the time interval of GPS measurement is smaller than 1 centimeter. This conclusion is valuable in the practical design of motion compensation systems for airborne SAR.