时间频率学报

针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题，提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台，在MAC层实现了硬件时间戳获取，避免了由于协议栈软件处理延时产生的不确定性；针对PTP时钟晶振老化导致的时间同步偏差及网络延迟抖动问题，采用迭代方法优化了本地时钟频率调节算法，提高了频率校正精度。经实际测试，主从时钟偏差的RMS(root mean square)优于20 ns，提升了时钟同步精度。

To address the issue of reduced clock synchronization accuracy caused by obtaining software timestamps at the application layer in PTP(precise time protocol) protocol, this paper proposes a PTP synchronization optimization scheme based on hardware timestamp acquisition at the MAC(media access control) layer. A PTP clock application platform was designed with STM32F407 microprocessor as the core,implementing hardware timestamp acquisition at the MAC layer to eliminate uncertainties introduced by software protocol stack processing delays. For the problems of time synchronization deviation caused by PTP clock oscillator aging and network delay jitter, an iterative method was adopted to optimize the local clock frequency adjustment algorithm, improving frequency correction accuracy. Actual test results demonstrate that the root mean square(RMS) deviation of the master-slave clock achieves better than 20 nanoseconds,significantly enhancing clock synchronization precision.