Definition and implementation of a new service for precise GNSS positioning
Definition and implementation of a new service for precise GNSS positioning
复制标题
DOI：
--
复制
发表时间：
2017-09
期刊：
影响因子：
--
通讯作者：
Paulo Sérgio De Oliveira Junior
中科院分区：
文献类型：
--
作者：
Paulo Sérgio De Oliveira Junior
PPP（Precise Point Positioning，精密单点定位）是一种基于SSR（State Space Representation，状态空间表示）概念的GNSS（Global Navigation Satellite Systems，全球导航卫星系统）方法。由于最近大气模型的改进，实时PPP（RT-PPP）也可以得到改进。这项工作的主要目标是研究RT-PPP和优化的基础设施的成本和效益，以实现使用大气校正的方法。因此，使用了法国现有的一个密集而规则的全球导航卫星系统网络-Orpheon网络的不同配置。该网络有大约160个站点，由Geodata-Diffusion（Hexagon Geosystems）拥有。最初，“浮动PPP-RTK”进行了评估，它对应于RT-PPP与网络校正带来的改进，虽然模糊度保持浮动。此外，网络校正应用于改善“PPP-RTK”，其中模糊度被固定到其整数值。对于浮动PPP-RTK，RTKLib 2.4.3（beta）包的修改版本用于应用网络校正。通过无电离层组合和对流层天顶延迟估计消除了电离层一阶效应。通过引入先验约束对流层参数来进行校正。基于OFC（最优拟合系数）的自适应建模已经被开发来描述对流层的行为，使用Orpheon站的对流层延迟的估计。此解决方案允许服务器和用户之间的单向通信。在收敛时间达到10厘米精度的增益进行了统计量化。通过使用稀疏网络配置减少参考站的数量（高达75%）来评估网络拓扑。在第二步中，使用PPP-Wizard 1.3软件和CNES（国家空间研究中心）的卫星轨道、时钟和相位偏差实时产品实现PPP-RTK。RT-IPPP（RT-IPPP）是通过估计对流层和电离层延迟来实现的。引入电离层和对流层改正作为PPP-RTK中的先验参数约束。为了产生电离层校正，实施了反距离加权（IDW）算法。由于来自（密集或稀疏）网络的外部SSR校正而在水平定位中实现的改进是有希望的，并且可能对主要依赖于水平定位的应用有用。
PPP (Precise Point Positioning) is a GNSS (Global Navigation Satellite Systems) method, based on SSR (State Space Representation) concept. Thanks to recent improvements in atmospheric models, Real-time PPP (RT-PPP) can also be improved. The main objective of this work is to study the RT-PPP and the optimized infrastructure in terms of costs and benefits to realize the method using atmospheric corrections. Therefore, different configurations of a dense and regular GNSS network existing in France, the Orpheon network, are used. This network has about 160 sites and is owned by Geodata-Diffusion (Hexagon Geosystems). Initially, ‘float PPP-RTK’ was evaluated, it corresponds to RT-PPP with improvements resulting from network corrections, although with ambiguities kept float. Further on, network corrections are applied to improve “PPP-RTK” where ambiguities are fixed to their integer values. For the float PPP-RTK, a modified version of the RTKLib 2.4.3 (beta) package is used to apply network corrections. First-order ionospheric effects were eliminated by the iono-free combination and zenith tropospheric delay estimated. The corrections were applied by introducing a priori constrained tropospheric parameters. Adaptive modeling based on OFCs (Optimal Fitting Coefficients) has been developed to describe the behavior of the troposphere, using estimates of tropospheric delays for Orpheon stations. This solution allows one-way communication between the server and the user. The gains achieved in convergence time to 10 centimeters accuracy were statistically quantified. Network topology was assessed by reducing the number of reference stations (up to 75%) using a sparse network configuration. In the second step, PPP-RTK is realized using the PPP-Wizard 1.3 software and CNES (Centre National d'Etudes Spatiales) real-time products for orbits, clocks and phase biases of satellites. The RT-IPPP (RT-Integer PPP) is performed with estimation of tropospheric and ionospheric delays. Ionospheric and tropospheric corrections are introduced as a priori parameters constrained in PPP-RTK. To generate ionospheric corrections, it was implemented an Inverse Distance Weighting (IDW) algorithm. Improvements achieved in horizontal positioning due to external SSR corrections from a (dense or sparse) network are promising and may be useful for applications that depend primarily on horizontal positioning.