GLONASS频间码偏差实时估计方法及其在RTK定位中的应用

GLONASS伪距频间偏差难以利用经验模型消除。在RTK定位解算中，尤其是需顾及大气延迟的中长距离异质基线，IFCB会降低模糊度收敛速度，甚至导致模糊度固定错误。本文基于双差HMW组合和消电离层组合，提出一种站间IFCB实时估计算法，实时获取各频段的非组合站间单差IFCB。试验结果表明，站间IFCB长期稳定，可达数个纳秒；在GPS/GLONASS观测值先验误差比值为3：5的条件下，未改正的IFCB可能导致基线GPS/GLONASS组合RTK定位性能比单GPS差。将本文提出算法应用于RTK定位，能够有效消除IFCB的影响，RTK模糊度浮点解精度、定位收敛速度和固定率都有明显改善，部分基线的RTK定位首次固定时间从9.2 s提高到2.1 s，固定解比率从84.5%提高到97.9%。

A real-time estimating algorithm of GLONASS inter-frequency code bias and its application in RTK

It is difficult to eliminate GLONASS inter frequency code bias(IFCB)by empirical model.In RTK positioning,especially for medium and long-distance heterogeneous baselines that need to take into account atmospheric delay,IFCB will reduce the convergence rate of ambiguity,and even cause incorrect ambiguity solutions.In this paper,a real-time estimation algorithm of inter-station IFCB is proposed.The new algorithm origins from the classical double differenced Hatch-Melbourne-Wübbena(HMW)combination and ionospheric free combination,can obtain precise IFCB after a short period of filtering.The experiment results show that IFCB between stations may up to several nanoseconds and are stable for a long time.As a ratio 3∶5 of the prior error of GPS/GLONASS observations,the uncorrected IFCB may cause the performance of GPS/GLONASS RTK positioning worse than that of single GPS.The proposed algorithm can effectively mitigate the negative influence of IFCB,including the accuracy of ambiguity floating solutions,the convergence speed and fixed rates of RTK positioning results.For some baselines,the time to first fixed of RTK positioning accelerate from 9.2 s to 2.1 s,and the fixed solution ratios enhance from 84.5%to 97.9%.