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星载合成孔径激光雷达对卫星成像面临相对运动复杂、目标搜索困难、成像时机难把握等问题。以对静止轨道卫星成像为例,初步设计了一种适于对同步轨道卫星成像的载星轨道。推导了载星与目标间相对运动关系式;绘制并分析了两星相对运动曲线;分析了两星距离最近期间距离、径向速度、加速度变化规律。提出了基于径向速度门限的成像时机判定方法,研究了成像期间光束指向偏移和成像时机判决速度门限。研究结果表明:轨道高度低于目标星轨道,并与之有一定偏角的载星轨道适于对目标进行成像;两星相距最近的时间附近是较佳成像时机,可降低相位误差补偿难度,提高系统工作效率;在对目标进行搜索跟踪和判决成像时机时,系统需根据两星轨道特性进行动态调整。
The satellite-borne synthetic aperture laser radar is facing the problems of complex relative motion, difficult target search and difficult imaging timing for satellite imaging. Taking geostationary orbit satellite imagery as an example, a satellite orbit that is suitable for satellite imaging of synchronous orbit has been preliminarily designed. The relationship between the relative movement between the carrier and the target is derived. The relative motion curve of the two stars is drawn and analyzed. The variation of distance, radial velocity and acceleration between the two stars is analyzed. The imaging timing decision method based on the radial velocity threshold was proposed. The thresholds of the beam pointing shift and imaging timing decision speed during imaging were studied. The results show that the orbit with orbital altitude lower than the target orbit is suitable for imaging the target. The best imaging timing near the closest distance between the two stars can reduce the difficulty of phase error compensation, Improve the work efficiency of the system. When searching for the target and timing of the decision imaging, the system needs to dynamically adjust according to the characteristics of the two-star orbit.