Ambiguity resolution in precise point positioning with hourly data
Ambiguity resolution in precise point positioning with hourly data
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DOI：
10.1007/s10291-009-0119-2
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发表时间：
2009-09-01
期刊：
影响因子：
4.9
通讯作者：
Liu, J.
中科院分区：
文献类型：
--
作者：
Geng, Jianghui;Teferle, F. N.;Liu, J.
精密单点定位（PPP）已成为全球定位系统（GPS）测量数据科学分析的有力工具。直到最近，由于接收机和卫星相关的未校准硬件延迟（UHD），PPP中单个台站的模糊度求解一直被认为是困难的。然而，最近的研究表明，如果这些UHD可以提前准确地确定在一个网络中的站，然后在一个单一的站模糊度的解决方案成为可能。在该研究中，采用Ge等人J Geod 82（7）：389-399，2007提出的方法，其中在区域网络上的每次全通过内仅确定一对卫星之间的一个单差窄巷UHD。本研究使用EUREF（欧洲参考框架）永久网络（EPN）确定2007年第245天至第251天的UHD。然后利用EPN内的12个国际GNSS服务站和EPN外的15个国际GNSS服务站进行每小时PPP的模糊度解算。结果表明，EPN内各测站每小时的平均定位精度分别从东、北、上分量的（3.8，1.5，2.8）cm提高到（0.5，0.5，1.4）cm。对于EPN以外的台站，其中一些距离最近的EPN台站超过2,000 km，当将基于EPN的UHD应用于这些台站时，东、北、上方向的平均定位精度仍然分别达到（0.6，0.6，2.0）cm。这些结果表明，在一个单一的站模糊度的解决方案可以显着提高每小时PPP的定位精度。特别是，UHD甚至可以应用于距离UHD确定网络数千公里的站点，这可能比当前基于网络的GPS增强系统具有很大的优势。因此，全球定位系统区域网络运营商和基于公私伙伴关系的在线服务提供商将这些超高度估计数作为一种额外产品提供是可行和有益的。
Precise point positioning (PPP) has become a powerful tool for the scientific analysis of Global Positioning System (GPS) measurements. Until recently, ambiguity resolution at a single station in PPP has been considered difficult, due to the receiver- and satellite-dependent uncalibrated hardware delays (UHD). However, recent studies show that if these UHD can be determined accurately in advance within a network of stations, then ambiguity resolution at a single station becomes possible. In this study, the method proposed by Ge et al. J Geod 82(7):389-399, 2007 is adopted with a refinement in which only one single-difference narrow-lane UHD between a pair of satellites is determined within each full pass over a regional network. This study uses the EUREF (European Reference Frame) Permanent Network (EPN) to determine the UHD from Day 245 to 251 in 2007. Then 12 International GNSS Service stations inside the EPN and 15 outside the EPN are used to conduct ambiguity resolution in hourly PPP. It is found that the mean positioning accuracy in all hourly solutions for the stations inside the EPN is improved from (3.8, 1.5, 2.8) centimeters to (0.5, 0.5, 1.4) centimeters for the East, North and Up components, respectively. For the stations outside the EPN, some of which are over 2,000 km away from the nearest EPN stations, the mean positioning accuracy in the East, North and Up directions still achieves (0.6, 0.6, 2.0) centimeters, respectively, when the EPN-based UHD are applied to these stations. These results demonstrate that ambiguity resolution at a single station can significantly improve the positioning accuracy in hourly PPP. Particularly, UHD can be even applied to a station which is up to thousands of kilometers from the UHD-determination network, potentially showing a great advantage over current network-based GPS augmentation systems. Therefore, it is feasible and beneficial for the operators of GPS regional networks and providers of PPP-based online services to provide these UHD estimates as an additional product.