BeiDou Time Synchronization for Rail Transit Operation Network

Atomic frequency standard of BeiDou system is a frequency source with excellent frequency stability and accuracy. Rail transit is a complex system with high safety requirement. Time synchronization can be in Rail transit operation system in order to realize the positioning navigation, time keeping dissemination and communication. Only achieved time synchronization of all signal equipment of train operation control system, can communication delay between onboard and ground equipment be minimized. Furthermore, the accuracy of train positioning can also be improved and the number of accidents caused by positioning faults will decrease. In this paper, a new rail transit time synchronization network has been proposed. With application of BeiDou timing and satellite communication technology, synchronization accuracy can be improved to nano-second-level. And it is also considered when space-based satellite fails to provide high-quality time signals, which can be solved by train-to-train communication and ground-to-train communication. This research is valuable for forming a large-scale, full-coverage rail transit time synchronization network and achieve unified management of national rail lines.