削弱GNSS多路径效应的半天球格网点建模方法

多路径效应与测站观测环境相关,无法利用差分的方式消除或削弱,是GPS精密数据处理时的主要误差源。为此,本文提出了一种利用半天球格网点模型削弱测站多路径误差影响的新方法MHGM(multi-point hemispherical grid model)。该方法对以测站为球心的半天球进行格网点划分,通过格网点的参数化描述,实现测站处多路径误差建模,可适用于现有各类GPS数据处理的软硬件设备和观测环境。本文算例的测试结果表明,采用新方法建模后双差观测值残差的RMS均值改善率平均在73.9%左右,较传统恒星日滤波方法的改善效果平均可提升26.9%,对于静态观测数据,按实时动态相对定位处理模式可获得平面精度约1.7 mm,高程精度约3.0 mm的定位结果。此外,MHGM模型还可进一步用于对测站周边可能存在的多路径误差源进行方位评估,对从物理意义上消除多路径误差源的影响给出一定的指导性意见。

A method for mitigating GNSS multipath effect based on multi-point hemispherical grid model

Multipath effect is related to the observational environment of stations, and cannot be eliminated or mitigated by differential algorithm. It is a major factor affecting accuracy and reliability in GPS signal processing. This paper proposes a method to mitigate the multipath effect—MHGM (Multi-point Hemispherical Grid Model). The method divides the hemisphere centered on each station into a grid, and estimates the multipath error at the station based on parametrization of the grid points, which can be applied to different kinds of hardware and software system of GPS data processing and observation environment. The experimental results in this paper show that, MHGM multipath error modeling based on data from observations made improvements in the mean RMS of double-differenced observation residuals averaging about 71.3%, an average increase of 26.9% compared with the traditional sidereal filtering method, the positioning results of 1.7 mm in level and 3.0 mm in altitude are obtained for static observation using real-time kinematic relative positioning mode. MHGM proposed in this paper also can used to assess orientation of error sources around the station, giving guidance which may assist in the physical elimination of sources of multipath error.