基于星上天线仰角约束的星间可视卫星集解析算法

An Analytical Algorithm for Inter-Satellite Visibility Calculation with Restriction of Satellite Antenna's Elevation

星座自主导航需要对星间可视性规律做定量分析，可为进一步研究星间自主组网策略以及星间网络拓扑设计提供理论依据，同时星上自主建立星间链路需要卫星已知其可视卫星集合，因此有必要研究星间可视性解析算法。建立了基于星上环带天线仰角约束的星间可视性判定模型，结合星座几何特性以及卫星运动规律，以时间为变量，推导了卫星在运动过程中对同轨道面与异轨道面可见卫星集合的解析算法，该算法元需通过遍历卫星两两之间的可视性便可解算出目标卫星的可视卫星集合。采用上述算法对GALILEO系统卫星星座星间可视性进行了分析，结果并与STK的仿真结果一致，从而验证了算法的正确性。分析结果表明，在25°－65°的仰角约束下，卫星与星座中8颗卫星永久可视，与异轨道面所有卫星可视时间占轨道运行周期的41．4％。本文的计算方法也可用于分析其他近圆轨道星座的星间可视性。

Analytical algorithm for inter-satellite visibility is essential for quantitative analysis of constenation visibility characteristic, which is important for the design of inter-satellite link （ISL） assignment scheme and the design of satellite network topology of autonomous navigation system. Analytical algorithm of inter-satellite visibility is necessary for a satellite to assign ISL autonQmously with others. Based on the restriction of scanning range of satellite annular antenna, this study introduced the rules to decide satellites＇ visibility. According to the Walker constellation＇ s spatial structure and satellite＇ s motion law, it introduced an analytical algorithm of satelllte＇s visibility with satellites in the same obit and different obit. Using the algorithm above to analyze satellites＇ visibility in Galileo constellation, the simulation results show that in the same and different obit plane each satellite has four visual satellites under the elevation restriction of [25°, 65°]. The algorithm is also available for the analysis of other circular-like constellation.