顾及频率间偏差的GPS/GLONASS卫星钟差实时估计

GPS/GLONASS卫星钟差联合估计过程中，由于GLONASS系统采用频分多址技术区分卫星信号，因而会产生频率间偏差（IFB）^1]。本文在GPS/GLONASS卫星定轨过程中的IFB参数特性分析的基础上，引入IFB参数，实现顾及频率间偏差的GPS/GLONASS卫星钟差实时估计。同时，为解决实时估计中待估参数过多导致的实时性较弱等问题，基于非差伪距观测值和历元间差分相位观测值改进实时估计数学模型，实现多系统卫星钟差的联合快速估计。结果表明：GPS/GLONASS联合估计时需引入IFB参数并优化其估计策略，采用MGEX和iGMAS跟踪站的实测数据进行实时钟差解算，快速估计方法可实现1.6 s逐历元快速、高精度估计，与GBM提供的最终精密卫星钟差相比，GPS卫星钟差实时精度约为0.210 ns，GLONASS卫星约为0.298 ns。

Real-time GPS/GLONASS satellite clock estimation with GLONASS inter-frequency biases

GLONASS system generates inter-frequency bias (IFB) using frequency division multiple access technology to distinguish satellite signals in the process of GPS/GLONASS satellite clock estimation. Base on the analysis of IFB parameter characteristics in the orbit determination process, the IFB is considered on the real-time GPS/GLONASS satellite clock estimation. At the same time, in order to solve the problem of weak real-time caused by excessive parameters in this estimation process, the mathematical model is improved based on the non-difference pseudo-range observation value and the difference phase observation between the epochs. The results show that the clock estimation needs to consider the IFB and optimize its estimation strategy. The real-time clock is calculated by the MGEX and iGMAS tracking stations data and only costs 1.6 s of an epoch. Compared with the final precision satellite clock provided by GBM, the accuracy of GPS satellite clock is about 0.210 ns, and the GLONASS is about 0.298 ns.