Generating GPS satellite fractional cycle bias for ambiguity-fixed precise point positioning
Generating GPS satellite fractional cycle bias for ambiguity-fixed precise point positioning
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DOI：
10.1007/s10291-015-0483-z
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发表时间：
2016-10
期刊：
影响因子：
4.9
通讯作者：
Pan Li;Xiaohong Zhang;X. Ren;Xiang Zuo;Yuming Pan
中科院分区：
文献类型：
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作者：
Pan Li;Xiaohong Zhang;X. Ren;Xiang Zuo;Yuming Pan
随着精密单点定位(PPP)的发展，武汉大学大地测量与地球科学学院(SGG)目前正在常规生产GPS卫星分数周期偏差(FCB)产品，供全球PPP用户进行模糊度固定的PPP解算。我们简要介绍了购买力平价的理论背景，并提出了计算FCB产品的策略和模型。详细描述了两步(宽车道和窄车道)FCB估计方案的实际实现。利用GPS在静止、动态和低轨卫星上的测量数据，对FCB估计的质量和PPP模糊度解算(AR)的有效性进行了评估。与CNES FCBs的比较表明，我们的FCBs与CNES的FCBs具有良好的一致性。对于宽通道FCB，两种产品的差值几乎都在±0.05个周期内。窄巷胎心导联87.8%的差值位于±0.075周期之间，97.4%的差值位于±0.05周期之间。实验结果表明，与传统的模糊浮动PPP相比，固定模糊PPP的静态PPP的平均位置均方根值可以从(3.6，1.4，3.6)厘米提高到(2.0，1.0，2.7)厘米。东、北、上分量的平均精度提高分别达到44.4%、28.6%和25.0%。在观测时间为80分钟的运动学、模糊度固定的PPP测试中，在所有三个坐标分量的一西格玛水平上，位置精度均优于5厘米。与模糊度漂移、运动学PPP相比，模糊度固定PPP的定位偏差在东、北、上分别改善了约78.2、20.8和65.1%。当AR应用于相同的数据集时，Leo PPP测试的RMS在径向、切向和法向分别提高了Grace-A和Grace-B约23.0、37.0和43.0%。这些结果表明，SGG FCB产品可以高质量地生产出来，供世界各地的用户进行模糊度固定的PPP解决方案。
With the development of precise point positioning (PPP), the School of Geodesy and Geomatics (SGG) at Wuhan University is now routinely producing GPS satellite fractional cycle bias (FCB) products with open access for worldwide PPP users to conduct ambiguity-fixed PPP solution. We provide a brief theoretical background of PPP and present the strategies and models to compute the FCB products. The practical realization of the two-step (wide-lane and narrow-lane) FCB estimation scheme is described in detail. With GPS measurements taken in various situations, i.e., static, dynamic, and on low earth orbit (LEO) satellites, the quality of FCB estimation and the effectiveness of PPP ambiguity resolution (AR) are evaluated. The comparison with CNES FCBs indicated that our FCBs had a good consistency with the CNES ones. For wide-lane FCB, almost all the differences of the two products were within ±0.05 cycles. For narrow-lane FCB, 87.8 % of the differences were located between ±0.05 cycles, and 97.4 % of them were located between ±0.075 cycles. The experimental results showed that, compared with conventional ambiguity-float PPP, the averaged position RMS of static PPP can be improved from (3.6, 1.4, 3.6) to (2.0, 1.0, 2.7) centimeters for ambiguity-fixed PPP. The average accuracy improvement in the east, north, and up components reached 44.4, 28.6, and 25.0 %, respectively. A kinematic, ambiguity-fixed PPP test with observation of 80 min achieved a position accuracy of better than 5 cm at the one-sigma level in all three coordinate components. Compared with the results of ambiguity-float, kinematic PPP, the positioning biases of ambiguity-fixed PPP were improved by about 78.2, 20.8, and 65.1 % in east, north, and up. The RMS of LEO PPP test was improved by about 23.0, 37.0, and 43.0 % for GRACE-A and GRACE-B in radial, tangential, and normal directions when AR was applied to the same data set. These results demonstrated that the SGG FCB products can be produced with high quality for users anywhere around the world to carry out ambiguity-fixed PPP solutions.