Land mobile GNSS availability and multipath evaluation tool
Land mobile GNSS availability and multipath evaluation tool
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DOI：
10.1109/tvt.2005.853461
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发表时间：
2005-09-01
影响因子：
6.8
通讯作者：
Heddebaut, M
中科院分区：
文献类型：
--
作者：
Marais, J;Berbineau, M;Heddebaut, M
全球导航卫星系统在陆地运输系统中的应用已经得到广泛部署，而且肯定会继续增长，特别是在智能运输系统的框架内。然而，这种系统最著名的缺点之一是在密集的城市地区以及某些特定的嵌入式铁路环境中缺乏卫星可见性。这在很大程度上限制了全球导航卫星系统在扩展安全相关应用方面的使用。在本文中，提出了一种新的工具来预测从陆地运输用户的角度来看，卫星星座的可用性。该工具知道陆地车辆的轨迹，预测将接收的卫星数量，并产生能够限定GNSS定位结果的安全标准。该工具的第一个版本已经投入使用，它将提供陆地环境知识的图像处理方法与预测天空中卫星位置的卫星跟踪程序的输出相结合。这使我们能够确定，使用一个简单的光学方法，在接收天线的附近环境的视线或阻挡接收到的卫星的数量。在铁路和公路环境中获得的结果表明，GNSS接收机在定位过程中经常使用通过多径接收的卫星信号。因此，表征了城市峡谷配置中的卫星信号的传播特性，以确定由反射射线接收的信号何时被接收器使用或不被使用。定义了与卫星仰角相关的准则，以提高预测工具的整体性能。与真实的测量比较的评论。模拟和测量是非常相似的。
Applications of global navigation satellite system (GNSS) in land transportation systems are already extensively deployed and will certainly continue to grow especially in the framework of intelligent transport systems. However, one of the best-known drawbacks of such a system is the lack of satellite visibility in dense urban areas as well as in some specific embedded railway environments. This restricts considerably GNSS use for extended safety related applications. In this paper, a new tool is proposed to predict the availability of a satellite constellation from the point of view of the land transportation user. Knowing the trajectory of a land vehicle, the tool predicts the number of satellites that will be received and produces a safety criterion able to qualify the GNSS localization result. A first version of the tool, already in operation, merges an image processing approach providing the knowledge of the land environment, and the output of a satellite tracking program predicting satellite positions in the sky. This allows us to determine, using a simple optical approach, the number of satellites received in line-of-sight or blocked, with regard to the nearby environment of the receiving antenna. Results obtained in railway as well as in road environments show that satellite signals received by multipath are often used by GNSS receivers in the localization process. Thus, propagation characteristics of the satellite signals in an urban canyon configuration were characterized to determine when a signal received by reflected ray is used by the receiver or not. A criterion related to the satellite elevation is defined to improve the overall performance of the predictive tool. Comparisons with real measurements are commented on. Both simulations and measurements are very similar.