星对星SAL成像中的振动误差分析

Vibration Error Analysis in Satellite-to-Satellite SAL Imaging

针对星体振动幅度较小、发生和持续时间不定、振动频谱复杂、检测难、误差补偿难等问题,依据SAL相干探测体制,给出了星体振动数学模型,分析了星体振动的频率、幅度特性。简要介绍了SAL成像算法原理,引入了星体振动误差模型。通过理论计算和仿真分析了不同频率、振幅的振动对距离向、方位向成像的影响。比较了不同振动起始时刻、持续时间条件下,成像质量受损情况,初步提出了抑制振动误差的思路。研究结果表明:频率低于1kHz的星体振动对SAL成像影响严重;振动持续时间越长对成像质量损害越严重;可通过增加合成孔径长度的方法或以降低分辨率为代价抑制振动损害。

Generally, Satellite’s vibration has small amplitude, complex spectrum, uncertain start time and duration, and is difficult to be detected accurately. The vibration’s amplitude and spectrum features are analyzed based on coherent detection of Synthetic Aperture Lidar （SAL）. The imaging algorithm theory of SAL is briefly introduced. Satellite’s vibration error model is introduced into SAL imaging. SAL’s range and cross-range imaging are closely analyzed by theory and simulation-based method. The various kinds of imaging quality loss corresponding with different start time and duration of vibration are investigated. Then a constructive vibration error compensation method is presented. The results show that the vibration’s frequency below 1 kHz can seriously affect imaging of SAL. The longer duration of vibration, more severe damage is caused on the imaging quality. Different time periods vibration can cause different imaging damage. Extending the length of synthetic aperture or reducing the resolution can suppress the damage of vibration error.