Faculty of Civil and Geodetic Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia.
Sensors (Basel). 2023 Mar 6;23(5):2861. doi: 10.3390/s23052861.
Low-cost dual-frequency global navigation satellite system (GNSS) receivers have recently been tested in various positioning applications. Considering that these sensors can now provide high positioning accuracy at a lower cost, they can be considered an alternative to high-quality geodetic GNSS devices. The main objectives of this work were to analyze the differences between geodetic and low-cost calibrated antennas on the quality of observations from low-cost GNSS receivers and to evaluate the performance of low-cost GNSS devices in urban areas. In this study, a simple RTK2B V1 board u-blox ZED-F9P (Thalwil, Switzerland) was tested in combination with a low-cost calibrated and geodetic antenna in open-sky and adverse conditions in urban areas, while a high-quality geodetic GNSS device was used as a reference for comparison. The results of the observation quality check show that low-cost GNSS instruments have a lower carrier-to-noise ratio (C/N) than geodetic instruments, especially in the urban areas where the difference is larger and in favor of the geodetic GNSS instruments. The root-mean-square error (RMSE) of the multipath error in the open sky is twice as high for low-cost as for geodetic instruments, while this difference is up to four times greater in urban areas. The use of a geodetic GNSS antenna does not show a significant improvement in the C/N and multipath of low-cost GNSS receivers. However, the ambiguity fix ratio is larger when geodetic antennas are used, with a difference of 1.5% and 18.4% for the open-sky and urban conditions, respectively. It should be noted that float solutions may become more evident when low-cost equipment is used, especially for short sessions and in urban areas with more multipath. In relative positioning mode, low-cost GNSS devices were able to provide horizontal accuracy lower than 10 mm in urban areas in 85% of sessions, while the vertical and spatial accuracy was lower than 15 mm in 82.5% and 77.5% of the sessions, respectively. In the open sky, low-cost GNSS receivers achieve a horizontal, vertical, and spatial accuracy of 5 mm for all sessions considered. In RTK mode, positioning accuracy varies between 10-30 mm in the open-sky and urban areas, while better performance is demonstrated for the former.
低成本双频全球导航卫星系统（GNSS）接收器最近已在各种定位应用中进行了测试。考虑到这些传感器现在可以以更低的成本提供高精度定位，它们可以被视为高质量大地型 GNSS 设备的替代品。本工作的主要目的是分析大地型和低成本校准天线在低成本 GNSS 接收器观测质量上的差异，并评估低成本 GNSS 设备在城市地区的性能。在这项研究中，一个简单的 RTK2B V1 板 u-blox ZED-F9P（瑞士 Thalwil）与一个低成本校准天线和一个大地型天线在开放天空和城市地区不利条件下进行了测试，而一个高质量大地型 GNSS 设备被用作比较的参考。观测质量检查的结果表明，低成本 GNSS 仪器的载波噪声比（C/N）低于大地型仪器，尤其是在城市地区，这种差异更大，对大地型 GNSS 仪器有利。在开放天空中，低成本仪器的多路径误差的均方根误差（RMSE）比大地型仪器高两倍，而在城市地区，这种差异高达四倍。在低成本 GNSS 接收器中，使用大地型 GNSS 天线并不能显著提高 C/N 和多路径。然而，当使用大地型天线时，模糊度固定的比例更大，在开放天空和城市条件下分别有 1.5%和 18.4%的差异。需要注意的是，当使用低成本设备时，浮动解可能会更加明显，特别是在短时间内和多路径较多的城市地区。在相对定位模式下，低成本 GNSS 设备在 85%的城市地区测量中能够提供水平精度低于 10 毫米，而垂直和空间精度在 82.5%和 77.5%的测量中分别低于 15 毫米。在开放天空中，低成本 GNSS 接收器在所有考虑的测量中均能达到 5 毫米的水平、垂直和空间精度。在 RTK 模式下，在开放天空和城市地区的定位精度在 10-30 毫米之间变化，而前者的性能更好。
