模糊度固定与弧段长度对区域站定轨的影响分析

我国北斗卫星导航系统难以实现境外全球布站,采用区域站观测值是实现高精度定轨的主要手段。本文分析了整网模糊度固定、有效定轨弧段选择对提高区域定轨精度的作用。采用陆态网GPS观测数据进行区域精密定轨仿真验证,首先论证了不同测站分布下,整网模糊度固定对区域定轨精度的效果,结果表明:相同测站条件下,固定解定轨精度比浮点解精度提高30%以上;仅采用国内7个站的固定解三维定轨精度即达到20 cm左右,优于27站的浮点解精度。另外,从星座的构型与地面站分布的可视范围方面,分析了不同观测时长对定轨精度影响,实测数据论证表明:当中国区域站观测时间大于48 h,总能获取不小于24 h的区域有效定轨弧段,并且各卫星最佳的24 h观测弧段三维定轨精度均可达到0.3 m左右。

Impact of Ambiguity Resolution and Arc Length on Regional Precise Orbit Determination

It is difficult for the BeiDou satellite navigation system to establish a global tracking network abroad, therefore regional tracking station observations are an important tool to achieve precise orbit determination (POD). Our investigation demonstrates that ambiguity resolution and reasonable arc length are important factors for improving the accuracy of regional orbit determination. GPS observations from CMONOC were adopted to simulate regional precise orbit determination; under the condition of the same station distribution, the accuracy of POD with ambiguity resolution was better than 30% with floating solution. Furthermore, the 3D RMS of an orbit with ambiguity resolution using seven stations was about 20 cm, better than the results of an ambiguity float solution using 50 stations. In addition, we evaluated the impact of arc length on POD accuracy from the satellite constellation design and the visible coverage of regional tracking stations. This experiment confirmed that when the observation time of regional stations is more than 48 hours, a valid arc length of regional POD, not less than 24 hours, can always be selected for each GPS satellite; the best selection can achieve a 3D accuracy about 0.3 m.