Multipath effect is one of the main errors in precise global navigation satellite system (GNSS) positioning. Although there are many GNSS multipath mitigation models available, each model has some limitations. We discuss the problem of mitigating low-frequency multipath in a specific site from the coordinate domain. At present, sidereal filtering is one of the most commonly used methods, in which the repetition period of multipath has to be estimated before multipath mitigation. However, in such a method, the maneuver of the satellite orbit and the long ephemeris update interval will cause inaccurate estimation of the repetition period. We propose a variation of the sidereal filtering method based on window matching. In that method, the window of coordinate time series formed by the current epoch and several previous epochs is used as the query window, and the matched window is searched in the time series of the previous day. The degree of similarity between windows is evaluated by similarity measures. Based on the coordinate point pairs in the matching window, multipath mitigation of the current epoch is performed by an affine transformation. The effects of different similarity measures in window matching are explored, and an early and late matching algorithm is proposed to solve the ambiguous problem of multiple matching sequences in integer-valued similarity metrics. Two sets of short baseline data were collected by different types of receivers in harsh environments to validate the method. The results show the feasibility and effectiveness of the proposed method for site-specific real-time multipath mitigation.

中文翻译：

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基于坐标时间序列窗口匹配的站点特定实时GPS多径缓解

多径效应是精确的全球导航卫星系统（GNSS）定位的主要错误之一。尽管有许多GNSS多径缓解模型可用，但每种模型都有一些局限性。我们讨论了从坐标域缓解特定站点中的低频多径问题。目前，恒星滤波是最常用的方法之一，其中必须在缓解多径之前估算多径的重复周期。然而，在这种方法中，卫星轨道的操纵和较长的星历更新间隔将导致重复周期的估计不准确。我们提出了一种基于窗口匹配的恒星滤波方法的变体。用这种方法 将当前纪元和前几个纪元形成的坐标时间序列窗口用作查询窗口，并在前一天的时间序列中搜索匹配的窗口。窗口之间的相似度通过相似性度量进行评估。基于匹配窗口中的坐标点对，通过仿射变换执行当前历元的多径缓解。探讨了不同相似性度量在窗口匹配中的作用，提出了一种早期和晚期匹配算法来解决整数值相似性度量中多个匹配序列的歧义问题。在恶劣环境下，不同类型的接收器收集了两组短基线数据以验证该方法。