Walker-δ星座轨道间激光链路的稳定性研究

Stability of inter-plane laser links in Walker-δ constellation

根据Walker-δ星座中相邻轨道卫星的相位差,引入轨道间激光链路连接参数K,建立参考卫星固联坐标系中目标卫星运动方程,得到不同轨道卫星之间方位角、俯仰角和距离(AER)的解析表示式,进而求出AER及其变化率极值的数值解。其中相邻轨道卫星的方位角变化率和变化范围都远大于俯仰角,对激光链路稳定性影响较大;方位角最大变化率同最小距离成反比,在极端情况下会超出激光通信终端跟踪范围导致链路中断。综合轨道间激光链路的稳定性和网络拓扑结构的复杂程度,得出相对连接相位为0是激光链路的低轨卫星星座连接配置方式。

The relative phase between the neighboring nodes in the adjacent planes of Walker-δ constellation was introduced as the connecting parameter K.The motion equations in the body-fixed coordinates system of reference satellite were established to obtain the azimuth angle,elevation angle and range（AER） of the inter-plane laser links.Then,the extremums of AER and the variation rates were calculated numerically.Among the AER,the azimuth angle rate,with the maximum value inversely ratio to the minimum range,impacts the stability of laser links significantly.In some extreme cases,it would be too fast to track the laser beam because of large azimuth angle velocities.K=0 is a good trade off between the links＇stability and the complexity of the network topology,and is fit for low earth satellite optical networks.