Zhu Feng, Zhang Huijun, Huang Luxi, Li Xiaohui, Feng Ping
National Time Service Center, Chinese Academy of Science, Xi'an 710600, China.
Technology and Engineering Center for Space Utilization, University of Chinese Academy of Science, Beijing 100039, China.
Sensors (Basel). 2020 Oct 25;20(21):6063. doi: 10.3390/s20216063.
The receiver delay has a significant impact on global navigation satellite system (GNSS) time measurement. This article comprehensively analyzes the difficulty, composition, principle, and calculation of GNSS receiver delay. A universal method, based on clock-steering characterization, is proposed to absolutely calibrate all types of receivers. We use a hardware simulator to design several experiments to test the performance of GNSS receiver delay for different receiver types, radio frequency (RF) signals, operation status and time-to-phase (TtP). At first, through the receivers of Novatel and Septentrio, the channel delay of Septentrio is 2 ns far lower than 65 ns for Novatel, and for the inter-frequency bias of GLONASS L1, Septentrio tends to increase within 10 ns compared with decreasing of Novatel within 5 ns. Secondly, a representative receiver of UniNav-BDS (BeiDou) is chosen to test the influence of Ttp which may be ignored by users. Under continuous operation, the receiver delay shows a monotone reduction of 10 ns as TtP increased by 10 ns. However, under on-off operation, the receiver delay represents periodic variation. Through a zero-baseline comparison, we verifies the relation between receiver delay and TtP. At last, the article analyzes instrument errors and measurement errors in the experiment, and the combined uncertainty of absolute calibration is calculated with 1.36 ns.
接收机延迟对全球导航卫星系统（GNSS）时间测量有重大影响。本文全面分析了GNSS接收机延迟的难点、组成、原理和计算方法。提出了一种基于时钟控制特性的通用方法，用于对所有类型的接收机进行绝对校准。我们使用硬件模拟器设计了几个实验，以测试不同接收机类型、射频（RF）信号、运行状态和时间到相位（TtP）情况下GNSS接收机延迟的性能。首先，通过诺瓦泰（Novatel）和Septentrio的接收机，Septentrio的通道延迟为2 ns，远低于诺瓦泰的65 ns，对于格洛纳斯（GLONASS）L1的频率间偏差，Septentrio倾向于在10 ns内增加，而诺瓦泰则在5 ns内减小。其次，选择一款具有代表性的宇达电通-北斗（UniNav-BDS）接收机来测试用户可能忽略的Ttp的影响。在连续运行下，随着TtP增加10 ns，接收机延迟呈现出10 ns的单调减小。然而，在开关操作下，接收机延迟呈现周期性变化。通过零基线比较，我们验证了接收机延迟与TtP之间的关系。最后，本文分析了实验中的仪器误差和测量误差，并计算出绝对校准的合成不确定度为1.36 ns。
