The primary master clock is located in the control center, including an external time signal receiver (GPS), rubidium clock, clock signal processing, generation, and distribution unit. It is composed of two master clocks, the main and backup, and can be automatically and manually switched between the main and backup clocks, serving as backup for each other.

　　The external clock signal receiving device is composed of GPS and rubidium clock signal interface units, which can receive GPS and rubidium clock calibration signals (and reserve other connections). The two channels are backup to each other and can be automatically switched; The frequency accuracy of the GPS clock source is greater than 10-10, and the frequency accuracy of the backup rubidium clock is greater than 10-9. The central primary master clock receives external standard time signals. The network management equipment of the clock system is located in the communication network management center of the control center, used for monitoring the clock subsystem of this project. The central primary master clock adopts a 19 inch standard cabinet with a height of 2200mm.

　　The slave clock is usually set up in the control center dispatch hall and related management rooms, as well as in the management rooms of the rolling stock depot.

　　The signal transmission between the master clock and the slave clock can use RS422 interface or Ethernet interface. This project adopts Ethernet interface. The power supply of the slave clock can be centralized or taken from nearby sources. It is recommended to use nearby sources to avoid excessive voltage drop caused by long distances, which may affect the normal operation of the slave clock equipment.

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