长基线GLONASS模糊度固定方法及实验分析

格洛纳斯（Global Navigation Satellite System，GLONASS）采用了频分多址技术，接收机在接收不同卫星信号时会产生频间偏差，阻碍了GLONASS长基线模糊度固定，限制了其定位定轨的精度。提出了一种新的GLONASS模糊度固定方法。该方法基于全球电离层格网产品，根据频间偏差率的变化范围，采用搜索的方法和线性模型去除相位频间偏差对宽窄巷模糊度的影响，实现了GLONASS无电离层组合模糊度固定。利用平均基线长度为763 km的全球卫星导航系统（Global Navigation Satellite System，GNSS）服务站实验网数据对该方法进行分析，结果表明:连续30 d内，模糊度固定成功率最高为95.4%，最低为88.8%，平均为93.45%；模糊度固定后，北（north，N）、东（east，E）、高（up，U）各分量重复性和均方根误差（root mean square er-ror，RMSE）值均得到不同程度的改善，E分量重复性和RMSE值分别改善了20%和14%，改善效果最为明显。

GLONASS Ambiguity Resolution Method Based on Long Baselines and Experimental Analysis

Frequency division multiplexing of GLONASS signals causes interfrequency bias(IFB) in the receiving equipment. IFB significantly prevents GLONASS ambiguity resolution and limits the accuracy and reliability of GLONASS positioning and orbit determination. Therefore, we present a new method for GLONASS ambiguity resolution. Firsly, it weakens the influence of inter-frequency code bias, and widelane ambiguities are calculated directly based on the wide-lane combined observations. Then, according to the range of inter-frequency phase bias rate, a step-by-step search schedule is designed to remove the im-pacts of inter-frequency phase bias on wide-lane and narrow-lane ambiguities. Finally, the ambiguity resolution can be achieved successfully. An IGS experiment network is carried out to verify the validity of this method. Experimental results show that the maximum, minimum and mean success rate of fixed ambiguities within the month were 95.4%, 88.8% and 93.45%, respectively. After ambiguity resolution, the repeatability and root mean square error (RMSE) of N, E, U components were improved; especially for E component, the repeatability and RMSE were improved 20% and 14%, respectively. This proves the validity of this method.