Multipath mitigation technique under strong multipath environment using multiple antennas
Multipath mitigation technique under strong multipath environment using multiple antennas
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DOI：
10.6125/17-0130-928
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发表时间：
2017-03
期刊：
影响因子：
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通讯作者：
N. Kubo;K. Kobayashi;Lt Hsu;O. Amai
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文献类型：
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作者：
N. Kubo;K. Kobayashi;Lt Hsu;O. Amai
多路径是城市环境中高精度全球导航卫星系统（GNSS）静态和动态差分定位的主要误差来源。本文介绍了一种独特的方法来减轻强多径误差：一种新的多径缓解技术，确保天线运动的漫游车移动平台的情况下，该平台正在缓慢移动或停止。已知当漫游器天线静止时，标准GNSS接收器易受多径干扰。这是因为当天线不移动时，由于直接信号和反射信号之间的载波相位关系变化缓慢，所以可以容易地接收稳定和强的多径信号。相反，当车辆移动时，直接信号和反射信号之间的接收载波相位关系迅速变化，这意味着强反射信号将被平均或消失。我们试图利用这一特点，以减轻强多径误差。进行了三个实验来评估所提出的技术。第一个测试结果说明了在静态条件下接收强镜面反射的情况。所提出的保持天线运动的技术可以将多径误差从超过15 m减小到1-2 m。在第二个测试中，通过比较两个紧密设置的天线，结果代表了汽车中多径缓解的情况：一个是天线固定在车顶上的地方;另一个是当汽车停止时故意手动摇动天线的地方。后一种情况可以减少当车辆在交叉口交通信号处停止时发生的显著的多径误差。最后，我们将5个贴片天线放置在汽车顶部，并通过为此目的开发的天线切换装置将这些天线连接到漫游车接收机。设备可以根据设置的切换周期进行天线切换。这使得天线看起来在移动，而汽车是停止或移动非常缓慢。设备本身很容易生产，成本低。数据是在静态条件下在建筑物附近获得的。在水平位置误差方面，使用我们所提出的方法的结果明显优于普通单天线的结果。最大水平误差减小约70%。
Multipath is a major source of error in high precision Global Navigation Satellite System (GNSS) static and kinematic differential positioning in urban environments. This paper describes a unique approach to mitigate strong multipath error: a new multipath mitigation technique ensuring that antenna motion for a rover-moving platform is maintained in the case that the platform is moving slowly or is stopped. It is known that standard GNSS receivers are vulnerable to multipath interference when the rover antenna is static. This is because stable and strong multipath signals can be easily received when the antenna is not moving, as the carrier phase relationship between the direct signal and the reflected signal changes slowly. Conversely, when a vehicle is moving, the received carrier phase relationship between the direct signal and the reflected signal changes rapidly, meaning that the strong reflected signal will be averaged or disappear. We attempt to use this characteristic to mitigate strong multipath errors. Three experiments were conducted to evaluate the proposed technique. The first test results illustrate the case of receiving strong specular reflection in a static condition. The proposed technique of maintaining antenna motion can reduce multipath errors from over 15 m to 1-2 m. In the second test, results represent the case of multipath mitigation in a car by comparing two closely set antennas: one is where the antenna is fixed on the roof of the car; the other is where the antenna is intentionally shaken manually while the car is stopping. The latter case can reduce significant multipath errors that occur while a vehicle is stopping at an intersection traffic signal. Finally, we set 5 patch antennas on top of a car and connect these antennas to rover receiver through the antenna switching devise developed for this purpose. The equipment can switch the antenna according to the set of switching period. This enables the antenna looks moving while the car is stopped or moving very slowly. The equipment itself is very easy to produce and low-cost. The data was obtained near the building in the static condition. Looking at the horizontal position errors, the results using our proposed method were clearly better than the results of normal single antenna. The maximum horizontal errors were reduced about 70 %.