An Approach to Speed up Single-Frequency PPP Convergence with Quad-Constellation GNSS and GIM.
An Approach to Speed up Single-Frequency PPP Convergence with Quad-Constellation GNSS and GIM.
复制标题
利用四星座 GNSS 和 GIM 加速单频 PPP 收敛的方法
DOI：
10.3390/s17061302
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发表时间：
2017-06-06
期刊：
影响因子：
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通讯作者：
Kuang C
中科院分区：
文献类型：
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作者：
Cai C;Gong Y;Gao Y;Kuang C
单频精密单点定位（PPP）技术因其精度高、成本低而受到越来越多的关注。然而，为了达到几厘米的定位精度水平，需要很长的收敛时间，通常是几个小时。本研究提出了一种结合四星座全球导航卫星系统（GNSS）和全球电离层地图（GIM）数据来加速单频PPP收敛的方法。在这种提出的方法中，GPS、GLONASS、北斗和伽利略观测结果直接用于未组合的观测模型中，因此电离层和硬件延迟（IHD）可以作为单个未知参数一起估计。然后将从 GIM 产品和多 GNSS 差分码偏差 (DCB) 产品获取的 IHD 值用作观测模型中 IHD 参数的伪可观测量值。还为伪可观量提出了时变权重方案，以在收敛期间逐渐减少其对位置解的贡献。为了评估所提出的方法，对连续 7 天来自 12 个多重全球导航卫星系统实验 (MGEX) 站的数据集进行了处理和分析。数值结果表明，与仅使用 GPS 的单频 PPP 相比，采用四星座 GNSS 和 GIM 数据的单频 PPP 在东、北和上方向的收敛时间分别减少了 56%、47%、41%。
The single-frequency precise point positioning (PPP) technique has attracted increasing attention due to its high accuracy and low cost. However, a very long convergence time, normally a few hours, is required in order to achieve a positioning accuracy level of a few centimeters. In this study, an approach is proposed to accelerate the single-frequency PPP convergence by combining quad-constellation global navigation satellite system (GNSS) and global ionospheric map (GIM) data. In this proposed approach, the GPS, GLONASS, BeiDou, and Galileo observations are directly used in an uncombined observation model and as a result the ionospheric and hardware delay (IHD) can be estimated together as a single unknown parameter. The IHD values acquired from the GIM product and the multi-GNSS differential code bias (DCB) product are then utilized as pseudo-observables of the IHD parameter in the observation model. A time varying weight scheme has also been proposed for the pseudo-observables to gradually decrease its contribution to the position solutions during the convergence period. To evaluate the proposed approach, datasets from twelve Multi-GNSS Experiment (MGEX) stations on seven consecutive days are processed and analyzed. The numerical results indicate that the single-frequency PPP with quad-constellation GNSS and GIM data are able to reduce the convergence time by 56%, 47%, 41% in the east, north, and up directions compared to the GPS-only single-frequency PPP.