VLBI在GEO卫星精密定轨中的应用

影响GEO轨道确定精度的原因主要有两方面:一是高轨卫星的几何跟踪条件受到局部测轨网的限制;二是卫星相对于地面的动力学约束信息较弱。利用一个针对GEO卫星的简化动力法定轨的协方差分析模型,研究了联合测距跟踪网和甚长基线干涉测量(VLBI)对定轨精度的改善情况。指出测距系统的校正误差是常规测距跟踪网定轨精度的主要误差源;当附加一条东西向VLBI基线时,仅利用不定期的少量VLBI高精度数据就能够显著改善测距偏差对轨道的影响,从而保证了卫星的整体位置解算精度。

VLBI-augmented Orbit Determination for Geostationary Satellites

There were two aspects that affect primarily the accuracy of angular position of geostationary satellites(GEOs).One was the limitation of regionally distributed tracking station network for such a high altitude spacecraft as GEOs, while the other was the weakness of GEO's dynamic equations in a rotational earth reference system.An approximate covariance analysis for orbit determination of geostationary satellites was given using two-way range data with and without VLBI-augmented measurements.The preliminary results indicated that range calibration bias,when larger than 1 meter,was the dominant error source for 10m-level orbit determination.By augmenting an east-west VLBI baseline within Chinese mainland,meter-level 3D components of the GEO orbit can be achieved with merely a couple of irregular VLBI data.