NTP和PTP协议的时间同步误差分析

Error Analysis of Time Synchronization in NTP and PTP

目前,NTP和PTP两种网络时间协议在电力系统中已经广泛应用,其同步原理及具体实现已有比较全面的分析,但针对两种同步协议的误差来源和数学模型则鲜见报道。为了进一步提高两种协议的时间同步精度,在梳理NTP和PTP的时间同步原理基础上,对同步过程中的误差来源进行了逐项建模,给出了误差的数学模型,最后利用现有设备进行了同步实验。实验结果表明,随着同步间隔的减小,本地时钟频率偏差引起的同步误差减小,同步精度因而提高;PTP由于使用了硬件时间戳,消除了网络协议栈的误差,同步精度远远高于NTP,达到了亚微秒量级。

Currently, the two network time protocol of NTP and PTP has been widely used in electric power system. Their synchronization principle and the concrete realization has been more comprehensive analysis, but for the error sources and mathematical models of the two synchronization protocols rarely reported. In order to further improve the accuracy of the time synchronization of the two protocols, model- ing synchronization error sources itemized, and mathematical model errors, and finally the use of existing equipment for the synchronous experiments, based on the organized of NTP and PTP time synchronization principle. Experimental results show that with the decrease of the synchronization interval, the local clock frequency synchronization error deviation caused by reduced thus improving the synchronization accuracy. And PTP due to the use of hardware timestamps, tion accuracy is much higher than NTP, reached eliminating the network protocol stack error, synchroniza- the sub-microsecond range.