Zhang Qiuzhao, Yang Wei, Zhang Shubi, Liu Xin
School of Environment Science and Spatial Informatics, China University of Mining and Technology, NO. 1 Daxue Road, Xuzhou 221000, China.
Sensors (Basel). 2018 Jan 12;18(1):198. doi: 10.3390/s18010198.
Global Navigation Satellite System (GNSS) carrier phase measurement for short baseline meets the requirements of deformation monitoring of large structures. However, the carrier phase multipath effect is the main error source with double difference (DD) processing. There are lots of methods to deal with the multipath errors of Global Position System (GPS) carrier phase data. The BeiDou navigation satellite System (BDS) multipath mitigation is still a research hotspot because the unique constellation design of BDS makes it different to mitigate multipath effects compared to GPS. Multipath error periodically repeats for its strong correlation to geometry of satellites, reflective surface and antenna which is also repetitive. We analyzed the characteristics of orbital periods of BDS satellites which are consistent with multipath repeat periods of corresponding satellites. The results show that the orbital periods and multipath periods for BDS geostationary earth orbit (GEO) and inclined geosynchronous orbit (IGSO) satellites are about one day but the periods of MEO satellites are about seven days. The Kalman filter (KF) and Rauch-Tung-Striebel Smoother (RTSS) was introduced to extract the multipath models from single difference (SD) residuals with traditional sidereal filter (SF). Wavelet filter and Empirical mode decomposition (EMD) were also used to mitigate multipath effects. The experimental results show that the three filters methods all have obvious effect on improvement of baseline accuracy and the performance of KT-RTSS method is slightly better than that of wavelet filter and EMD filter. The baseline vector accuracy on east, north and up (E, N, U) components with KF-RTSS method were improved by 62.8%, 63.6%, 62.5% on day of year 280 and 57.3%, 53.4%, 55.9% on day of year 281, respectively.
用于短基线的全球导航卫星系统（GNSS）载波相位测量满足大型结构变形监测的要求。然而，载波相位多路径效应是双差（DD）处理中的主要误差源。有许多方法可用于处理全球定位系统（GPS）载波相位数据的多路径误差。北斗导航卫星系统（BDS）的多路径抑制仍是一个研究热点，因为BDS独特的星座设计使其在抑制多路径效应方面与GPS有所不同。多路径误差会周期性重复，因为它与卫星几何形状、反射面和天线密切相关，而这些也具有重复性。我们分析了BDS卫星的轨道周期特征，这些特征与相应卫星的多路径重复周期一致。结果表明，BDS地球静止轨道（GEO）和倾斜地球同步轨道（IGSO）卫星的轨道周期和多路径周期约为一天，而中地球轨道（MEO）卫星的周期约为七天。引入卡尔曼滤波器（KF）和劳赫 - 通 - 施里贝尔平滑器（RTSS），与传统恒星滤波器（SF）一起从单差（SD）残差中提取多路径模型。小波滤波器和经验模态分解（EMD）也被用于减轻多路径效应。实验结果表明，这三种滤波方法对提高基线精度均有明显效果，且KF - RTSS方法的性能略优于小波滤波器和EMD滤波器。采用KF - RTSS方法时，在一年中的第280天，基线向量在东、北、上（E、N、U）分量的精度分别提高了62.8%、63.6%、62.5%；在一年中的第281天，分别提高了57.3%、53.4%、55.9%。
