基于 SGP4模型与多普勒频移的改进定轨方法

摘要

CubeSats always choose two-line element (TLE)in conjunction with the SGP4 model to deter-mine the orbit,or as a backup method.To settle the problem that the propagation error accumulates over time, the source and distribution of the errors are analyzed and two improved approaches are proposed by using Doppler shifts.One is to directly correct the drag coefficient and results show a significantly decrease in in-track orientation error.The position difference is improved to 4 km in 10 days.The other approach is to update the TLE epoch time to the pass time firstly,and then correct the argument of the latitude.Simulation results indi-cate that the position error can be almost removed in a short time but the long time performance is worse than the first method.The conclusion is also verified by actual measurements from the in-orbit CubeSats.%立方体卫星广泛使用两行根数（two-line element，TLE）结合 SGP4模型作为定轨的唯一或是备份手段。针对 SGP4模型长期预报误差积累的问题，分析了模型的误差来源及分布情况，提出两种利用地面观测站测量多普勒频移提高定轨精度的方法。一种方法直接修正大气阻力项系数，结果表明能大幅减小速度方向上的预报误差，将预报10天的位置精度提高到4 km 以内。另一种方法将已知的两行根数更新为卫星过境时刻的两行根数，然后修正纬度幅角，修正后短期预报误差能基本消除但长期精度不如前一种方法。通过对在轨立方体卫星的实际测量也验证了上述的结论。