已有文献中提出的基于收发波束指向控制的波束同步方法,在非合作式的星机双基地SAR中不适用。根据星机双基地SAR“远发近收”的特点,提出了一种宽波束接收工作模式用于提高场景长度。针对卫星过顶时间的估计误差和飞机导航系统的误差,提出了一种基于对直达波信号进行处理的补偿方案。仿真结果表明,该文提出的方法能在方位分辨率略好于单星SAR的前提下,使场景长度达到1km以上。
An existing approach for beam synchronization, which is based on antenna steering on both sides, can not be applied to Spaceborne/Airborne hybrid Bistatic SAR (SA-BSAR) systems using sources of opportunity since the transmitter beam can not be steered. An approach via wide-beam receiving is proposed. The inspiration comes from the fact that the receiving distance in SA-BSAR is much shorter than the one in spaceborne SAR systems. An approach for compensating the estimation error of the satellite overpass time and the error in the aircraft navigation system is also proposed. The compensation is implemented through the processing of the direct path signal. The results of the performed simulation show that it can achieve a useful scene extension (at least more than 1 km) with an azimuth resolution slightly superior to the one obtained in spaceborne SAR systems.