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Time Sync System Application for RAIL TRANSPORTATION

To ensure a safe and punctual operation of the urban rail transportation lines, a close cooperation between each department and system will be a must. Thus, setting a time synchronization system in the rail automation systems will be a guarantee for serving passengers and unifying time of whole rail transportation lines’ system standard time.

1.What can a time sync system do in the rail transportation?
1.1The time sync system can provide a unified time for the whole rail transportation lines. The unified time is normally displayed on digital clocks or analog clocks which are set in each station, to provide time info (including year, month, date, hour, minute, second and week/temperature etc) for passengers and rail transportation staffs.
1.2The time sync system can synchronize time of other automation systems, such as communication subsystems, ATS systems, SCADA systems, FAS systems, AFC systems etc. To guarantee a standard synchronized time for rail transit traffic command, train movements and system management.

2.System introduction

This Rail transportation time sync system consists of  central primary clock system, time monitoring system(optional), secondary master clock system, slave clock system and transmission channels. 

2.1 Central primary clock system

The central primary clock system are redundant TSS2000C ( which are manufactured by COVE TECHNOLOGY, having passed the cape laboratory type test, have the test report) receiving GPS time source and external time source via dual IRIG-B inputs as a back-up time standard. Central primary clock synchronize time to the control center, each station’s secondary master clocks and other related systems via serial ports or Ethernet ports.  

The central primary clock system provides fault alarm function, is able to transmit the fault information to the network monitoring system.

2.2 Time monitoring system (Optional)

The time monitoring system is a TMU001(which is manufactured by COVE TECHNOLOGY). It can real-time monitor the whole clock system operation status, failure management to provide fault information to network management system, performance management, configuration management and security management, statistics report and so on.

2.3 Secondary master clock system 
The secondary master clock systems are deployed in each station or parking lot where the slave clocks (digital clock or analog clock) need a time standard for their operation.
Through a standard interface, secondary master clock receives standard time signal from the central primary clock via a transmission system, shows the time information and calibrate internal time precision; At the same time, standard time signal can be sent to the affiliated slave clocks, to ensure the slave clocks display a unified time.
In addition, the secondary master clock also provides monitoring and fault alarm function, itself and its subordinate slave clock’s running status information and fault information can be sent back to central primary clock. 

System Structure

2.4Slave clock system 
Slave clocks are usually deployed at the station platforms, station halls and office etc., including digital clock and analog clock. The slave clocks receive time signal from secondary master clock via standard input interfaces, and display a unified time information.
When the external time signal is lost, slave clock keeps running time by its built-in oscillator for a period. When the signal’s recovered, it automatically calibrate it’s time to the standard one and display the correct time.
2.5Transmission channels
Common used transmission channels including serial ports (RS-232, RS422 and RS485), RJ45 Ethernet ports and Optical fiber ports.  In current urban rail transportation, the serial ports are mostly used.

Products apply for this solution include:

CT-DZ600A Satellite Synchronous Clock (NTP Time Server)

CT-GPS2003S NTP Time Server

CT-TSS2000C Grandmaster Clock

CT-DDT200/210 Series Digital Wall Clock