Jin Xiaozhen, Hua Yu
National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China.
Key Laboratory of Precise Positioning and Timing Technology, Chinese Academy of Sciences, Xi'an 710600, China.
Sensors (Basel). 2025 Jan 3;25(1):241. doi: 10.3390/s25010241.
Telephone time service is a wired time service that transmits time signals through a telephone network, with the advantages of simple receiving equipment and wide coverage. But the performance of time service is not high, usually several milliseconds. The time delay measurement of the telephone network is an important factor limiting the improvement in timing performance. The existing telephone service systems measure time delay based on sending characters. The time fluctuation of modulating and demodulating characters and the low accuracy of detecting characters affect the uncertainty of time delay measurement. This article proposes a time delay measurement method based on sending PN codes. It utilizes the good autocorrelation properties of PN codes to improve detection accuracy and then improve the uncertainty of delay measurement. This article studies and designs the modulation, demodulation, and capture of PN codes. Simulation has verified that this method has strong anti-noise performance. Time delay tests have proved that this method can improve the uncertainty of delay measurement by an order of magnitude in different telephone network environments.
电话授时服务是一种通过电话网络传输时间信号的有线授时服务，具有接收设备简单、覆盖范围广的优点。但授时性能不高，通常为几毫秒。电话网络的时延测量是限制定时性能提升的一个重要因素。现有的电话服务系统基于发送字符来测量时延。调制解调字符的时间波动以及字符检测的低精度影响了时延测量的不确定性。本文提出一种基于发送PN码的时延测量方法。它利用PN码良好的自相关特性来提高检测精度，进而提高时延测量的不确定性。本文研究并设计了PN码的调制、解调及捕获。仿真验证了该方法具有较强的抗噪声性能。时延测试证明，该方法在不同电话网络环境下可将时延测量的不确定性提高一个数量级。
