s7123a观测实验测角归算结果讨论

A Discussion on the Angular Positioning Reduction of the Experiment s7123a

讨论了2007年1月23日我国VLBI网4天线对某卫星跟踪观测实验（s7123a）的测角归算结果。分析指出，相比于仅仅解算卫星横向位置参数，解算三维位置改正的方式在原理上更为可取。通过s7123a跟踪数据不同组合情况下测角计算结果的比对和原理性分析，指出四站跟踪测角计算时，只有当距离约束与时延观测误差相当时才会对解有显著影响，而对于三站跟踪，虽然解的形式误差可能会很小，但解会受到卫星径向距离误差和时延系统误差的影响，不属于无偏估计。本文对于探月工程中的卫星VLBI测轨有参考意义。

This paper discusses the angular measurement reduction results of the tracking data by the four Chinese VLBI antennas to a satellite on January 23 of 2007. Analysis shows that compared with solely solving the corrections to the translational position parameters of satellite, it is more reasonable to solve all the three dimensional corrections. Through comparisons of the reduction results of various subset tracking data of s7123a as well as through theoretical analysis, it shows that the angular measurement reduction results of the tracking data from the four antennas could be affected significantly if only the constraint of the radial distance is on a comparable level to the delay errors in magnitude, while for the three tracking antennas, the formal error of unknowns could be very small, however, the solution could be biased due to the uncertainty in the radial distance of satellite and the systematic errors of delay observations. The discussion in this paper is valuable to the .VLBI tracking of satellite in the Chinese Lunar Exploration Project for reference.