中文摘要：

利用码和载波相位观测值半和线性组合可以消除电离层一阶误差的特性,讨论了基于UofC消电离层组合的GPS/GLONASS精密单点定位的数学模型。UofC模型对两个频率上的模糊度参数分别进行估计,为进一步获得模糊度参数的整数解提供了便利。利用IGS跟踪站的GPS/GLONASS观测数据对UofC模型和传统的在两个频率码观测值间进行消电离层组合的模型进行了比较,统计结果表明,UofC模型与传统模型相比在平面位置定位精度上略有提高,但总体上差别不大。

英文摘要：

Based on the fact that the half-sum linear combination of code and phase observations may remove the first-order ionospheric error, a mathematic model of the combined GPS and GLONASS precise point positioning （PPP） using UofC ionosphere-free combination is developed. The UofC PPP model estimates individually ambiguity parameters on two fre- quencies, which facilitate further obtaining integer solutions of ambiguities. The positioning results obtained from the UofC model and the traditional model in which code observations on two frequencies are used to form ionosphere-free combinations are compared using GPS/ GLONASS observation data from IGS tracking stations. The statistical results indicate that the UofC model performs slightly better in terms of the horizontal position accuracy. But the difference about the three-dimensional positioning accuracy is insignificant.