航天相机环扫成像模式设计

为了满足敏捷卫星广域搜索需求，设计了航天相机环扫成像模式。建立环扫成像模型，通过对环扫成像原理的分析，设计了成像的最优地面轨迹，并分析了此时临界卫星旋转速度与轨道速度、环扫临界系数、帧间重叠率的关系；同时基于地面轨迹设计了确定曝光时间、帧频等成像参数解算方案。通过Satellite Tool Kit（STK）软件对成像模型进行仿真，并对成像几何参数进行分析，结果表明:在轨道高度H为500 km，像素尺寸a为4 m，焦距f为1 m，轴向像元数M为50 000时，随着相机倾角的增加，地面像元分辨率与幅宽逐渐增大；等于10、20、30、40时，地面幅宽分别提升为星下点成像时的1.96、3.10、4.58、6.85倍。

Design of aerospace camera circular scanning imaging model

In order to meet the needs of wide area search using agile satellite, the aerospace camera circular scanning imaging model was designed. Based on analyzing the principle of the circular scanning imaging, the optimal ground track was designed and the relationship between the critical spin speed of the satellite and the orbital velocity, the critical circular scanning coefficient, the overlap rate was analyzed, the circular scanning model was established. At the same time, the exposure time, frame rate and other imaging parameters were determined based on the ground track design. The imaging model by STK software was simulated, and the imaging geometric parameters were analyzed. The result shows that when the orbital height H is 500 km, the pixel size a is 4 m, the focal length f is 1 m and the axial pixel number M is 50 000, the ground sample distance and swath width increase gradually with the increase of the camera inclination , when equals to 10, 20, 30, 40, the swath width raises to 1.96, 3.10, 4.58, 6.85 times compared with nadir imaging.