IEEE1588对时同频算法

IEEE1588 synchronization algorithm

为了提高IEEE1588对时精度,满足1μs以内对时精度的要求,需要在对从钟偏移量调整的基础上进行从钟频率调整以实现与主钟同频同相。现有的时钟同频算法仅根据相邻2次SYNC报文的收、发时间戳计算时钟频率差实现主、从钟同频。在IEEE1588V2透明时钟对时模式下,由于没有考虑到SYNC报文Correction域的影响,该算法无法收敛。提出了对该算法的改进,加入SYNC报文Correction域和时钟偏移量的修正,该算法可以快速收敛,快速实现从钟与主钟同频。通过实际测试系统,验证了改进后算法的可行性和准确性。

In order to improve the synchronization accuracy of IEEE1588 for meeting the requirement of better than 1μs,based on the adjustment of slave clock offset,the frequency and phase of slave clock are adjusted as those of the master clock.The existing synchronization algorithms only use the receiving /transmitting timestamps of two adjacent SYNC messages to calculate the frequency difference between master and slave clocks for synchronization.As the influence of correction field in SYNC message is not considered in the transparent clock mode of IEEE1588 version2.0,the algorithm becomes nonconvergent.An improved algorithm is proposed,which converges quickly by modifying the Correction field of SYNC message and clock offset.Its feasibility and precision are verified by the test system.