Time-shared bidirectional repeatered system for scalable sensor network with absolute time synchronization

摘要

This paper describes a new approach to realize a bidirectional repeater suitable for sensor networks with absolute time synchronization, and discuss propagation delay measurements of an experimental bidirectional repeatered system. A time-shared quasi-bidirectional linear repeater, that enables to the direction of signal flow to be changed. It uses a unidirectional EDFA, an optical router module composed of magneto-optic components and a delay fiber. The repeater has realized identical propagation delay for both directions of signal flows and attained multipath interference free amplification of optical packet signals for absolute time synchronization and sensing. A 50.078 km bidirectional repeatered line varied its propagation delays by 1.2 ns for both directions of signal flow with laboratory temperature change. Nevertheless, the experimental setup has not detected the propagation delay difference between both directions of signal flows that exceeded +/- 30 ps. This means that highly accurate absolute time synchronization will be feasible using bidirectional transmission system equipped with the time-shared quasi-bidirectional linear repeaters.