北斗导航卫星星上参考基准研究

Pseudo-range / carrier-phase observation and satellite laser ranging are two main tracking methods on navigation satellites, which basic onboard reference points correspond to radio antenna phase center and optical (laser) phase center, respectively. In this study, two types of observation information will be fully utilized, and the characters and effects of the two types of phase centers will be analyzed completely, and in this process the emphasis lies in the analysis of the locations and variations of phase centers and their relative positions to satellite mass center. The major concerned include: the differences between two types of phase centers, the estimation scheme of their relative corrections; the estimation on the locations of two types of phase centers by means of “onboard-local-tie” combined solution, so as to achieve the goal of improving the estimation accuracy and keeping the internal consistency. The final objective is to provide a set of self-consistent parameterized phase-center correction models on BeiDou navigation satellites. The precise determination of onboard reference points will be helpful to improve the level of orbit determination and positioning of BeiDou satellites, and contribute to better navigation function of BeiDou system.

伪距/载波相位观测和卫星激光测距是导航卫星最主要的两种观测手段，其星上参考基准点分别对应于星上天线相位中心和光学相位中心。本项目将充分利用两种观测信息，完整分析北斗导航卫星两类相位中心的性质与影响，重点分析两类相位中心位置、变化及其与卫星质心的相对关系。主要研究两类相位中心的差异、改正值的估算方案；通过星上约束的方式联合解算两类相位中心的位置，以提高解算精度，并使其具有一致性；最终提出一套自洽的北斗导航系统卫星参数化相位中心改正模型。北斗导航卫星星上参考基准点的精确确定，将提高系统定轨定位精度，提升北斗系统的导航功能。

作为导航卫星最主要也是最精确的两种观测手段，无线电波段的伪距/载波相位无线电观测和光学波段的卫星激光测距在星上参考基准点分别对应于星上天线相位中心和光学相位中心。二者的测定精度和自洽性对卫星导航系统定轨定位有着重要意义。本项目的研究仔细分析了导航卫星相位中心改正模型，对SLR和无线电轨道系统差进行了分析，确认了太阳光压模型对轨道精度的影响，提出了轨道精度变化的可能解释，对北斗区域网轨道的特点进行了揭示和分析，仔细研究了北斗卫星SLR相位中心改正，讨论了SLR精密定轨精度，并进一步完善了我们的精密定轨及轨道精度评估平台，利用星载全球卫星导航系统观测数据对多颗低轨卫星实现了高精度轨道确定以及包括SLR检核在内的详细的轨道精度评估。本项目的研究表明，对导航卫星星上参考基准点特性的研究将有助于提高卫星导航系统定轨精度及整体性能。