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.