Time Synchronization of White Rabbit Network Based on Kalman Filter

White Rabbit (WR) is a high-precision fiber time-frequency synchronization technology based on Synchronous Ethernet (SyncE), PTPv2 and Digital Dual Mixer Time Difference (DDMTD). The use of a DDMTD phase detector enhances the accuracy of time synchronization to less than nanoseconds. However, the DDMTD requires additional hardware support. Additionally, the large jitter of the master-slave clock will lead to the reduced accuracy of the phase difference measurement, which affects the convergence speed of synchronization. Based on the analysis of the basic principle of WR technology, this paper studies the factors affecting WR time synchronization in detail, and establishes the master-slave clock offset and frequency deviation noise model. Based on this, the Kalman filter algorithm is used to estimate the clock offset and frequency deviation. Kalman filter is designed and verified by simulation. Experimental results show that the application of Kalman filtering in WR network can reduce the hardware complexity and ensure the time synchronization accuracy of ns level.