Characterization of 1 Gbps fiber optics transceiver for high accuracy synchronization over Ethernet

摘要

Large experiments for studying high energy physics phenomena are requiring accurate time synchronization. The wide area occupied by such kind of facilities challenges the achievable accuracy using traditional time distribution systems. At CERN, the White Rabbit (WR) project extended the Precision Time Protocol (PTP) in order to provide sub-nanosecond accuracy with standard deviation less than 50 ps. As a matter of fact, the WR systems relies also on the frequency syntonization of the L1 frontend to limit the local clock synchronization uncertainty. In particular, this work is focused only on the contribution related to the jitter of the Network Layer 1 (L1) (1 Gbps fiber optic transceiver) to the overall uncertainty. An experimental setup is proposed and the real implementation of the WR system is tested. The results show that under steady conditions the impact of the fiber optic transceiver on the overall jitter transfer is restricted to less than 0.3 ps RMS, practically negligible with respect to other uncertainty contributions of the whole system.