Weighting of Multi-GNSS Observations in Real-Time Precise Point Positioning
Weighting of Multi-GNSS Observations in Real-Time Precise Point Positioning
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DOI：
10.3390/rs10010084
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发表时间：
2018-01-01
期刊：
影响因子：
5
通讯作者：
Sosnica, Krzysztof
中科院分区：
文献类型：
--
作者：
Kazmierski, Kamil;Hadas, Tomasz;Sosnica, Krzysztof
全球导航卫星系统（GNSS）的组合可以提高估计坐标的准确度和精度，以及精密单点定位（PPP）解决方案的收敛时间。关键条件是正确的功能模型和观测值的适当加权，为此应考虑到多重全球导航卫星系统信号的不同特点。在后处理应用中，可以通过分析后拟合残差来获得最佳的随机模型，但是对于实时应用，必须预先定义随机模型。针对GPS + GLONASS + Galileo + BeiDou组合，提出了五种不同的加权方案，其中两种方案没有系统内差异，三种方案基于信号噪声和/或卫星轨道质量。我们只执行GPS和五个多GNSS解决方案，代表每个加权方案。我们分析了坐标的形式误差，坐标的重复性，和解决方案的收敛时间。我们发现，不适当的或相等的权重可能会改善正式的错误，但降低坐标的可重复性相比，只有GPS的解决方案。基于卫星轨道质量的系统内加权允许将形式误差减少40%，将水平和垂直分量的收敛时间分别缩短40%和47%，以及将坐标重复性提高6%。
The combination of Global Navigation Satellite Systems (GNSS) may improve the accuracy and precision of estimated coordinates, as well as the convergence time of Precise Point Positioning (PPP) solutions. The key conditions are the correct functional model and the proper weighting of observations, for which different characteristics of multi-GNSS signals should be taken into account. In post-processing applications, the optimum stochastic model can be obtained through the analysis of post-fit residuals, but for real-time applications the stochastic model has to be defined in advanced. We propose five different weighting schemes for the GPS + GLONASS + Galileo + BeiDou combination, including two schemes with no intra-system differences, and three schemes that are based on signal noise and/or quality of satellite orbits. We perform GPS-only and five multi-GNSS solutions representing each weighting scheme. We analyze formal errors of coordinates, coordinate repeatability, and solution convergence time. We found that improper or equal weighting may improve formal errors but decreases coordinate repeatability when compared to the GPS-only solution. Intra-system weighting based on satellite orbit quality allows for a reduction of formal errors by 40%, for shortening convergence time by 40% and 47% for horizontal and vertical components, respectively, as well as for improving coordinate repeatability by 6%.