GB/T 45308-2025 Railway applications―Rolling stock―Technical requirements for network time synchronization English, Anglais, Englisch, Inglés, えいご
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ICS 45.060
CCS S 30
National Standards of the People's Republic of China
GB/T 45308-2025
Railway applications – Rolling stock - Technical requirements for network time synchronization
轨道交通 机车车辆 网络时间同步技术要求
(English Translation)
Issue date: 2025-02-28 Implementation date: 2025-09-01
Issued by the State Administration for Market Regulation
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Abbreviations
5 Technical requirements
6 Performance test
Bibliography
Railway applications – Rolling stock - Technical requirements for network time synchronization
1 Scope
This document specifies the technical requirements and performance tests for network time synchronization of rail transit rolling stock.
This document applies to rail transit rolling stock train communication network (TCN) equipment.
2 Normative references
The contents of the following documents constitute the essential provisions of this document through normative references in the text. Among them, for the referenced document with a date, only the version corresponding to that date is applicable to this document; The latest version of the undated referenced document (including all amendments) is applicable to this document.
GB/T 17737.1 Coaxial communication cables - Part 1: General Specification General Principles, Definitions and Requirements
GB/T 24338.4 Rail transit-Electromagnetic compatibility - Part 3-2: Rolling Stock Equipment
GB/T 25119 Electronic device of rail transit rolling stock
GB/T 28029.1-2020 Rail transit electronic equipment - Train communication network (TCN) - Part 1: Basic structure
GB/T 28029.9-2020 Rail transit electronic equipment - Train communication network (TCN) - Part 3-1: Multifunction Vehicle Bus (MVB)
GB/T 28029.12-2020 Rail transit electronic equipment - Train communication network (TCN) - Part 3-4: Ethernet Marshalling (ECN)
GB/T 37943-2019 Test Method of BeiDou Satellite Timing Terminal
TB/T 1484.3-2017 Rolling stock cables - Part 3: Communication cable
JJF (Communications) 018-2021 Specification for calibration of time synthesis tester
3 Terms and definitions
The terms and definitions defined in GB/T 28029.1-2020 and the following are applicable to this document.
3.1
time reference
BeiDou time is used as the initial time reference and atomic time is used as the standard time based on the time unit (s)
3.2
time accuracy
degree of consistency between the local clock and the time reference measured over a certain time interval
Note: Expressed as the absolute value of the time deviation.
3.3
local time accuracy
in the state of punctuality, the consistency between the local clock and the time reference measured within a specified time interval
Note: Expressed as the absolute value of the time deviation.
3.4
correct time accuracy
in the timing state, the degree of consistency between the timing clock and the timed clock
Note: Expressed as the absolute value of the time deviation.
3.5
time stability
degree of change in time accuracy due to the intrinsic factors of the clock or environmental influence within 1s
Note: Expressed as standard deviation of time deviation.
3.6
clock device
device capable of issuing or receiving time synchronization protocol messages on a network
3.7
clock source
device capable of receiving a time reference signal and providing time information
3.8
external clock source
device that can receive BeiDou time reference signal and provide time information
Note: Such as on-board signal devices, Chinese locomotive remote monitoring and diagnosis systems, on-board information wireless transmission equipment and independent timing equipment, etc.
3.9
master clock
device that transmits a time synchronization protocol message to a slave clock
3.10
slave clock
device for time synchronization using a time reference of a master clock
3.11
operational clock
system running clock of the time synchronization device
Note: Also called software clock.
3.12
local clock
own clock of the time synchronization device
Note: Also called hardware clock.
3.13
clock domain
logical combination of devices that can accomplish time synchronization according to the same communication transmission specification
3.14
time synchronization
operation process of causing two or more clocks to have the same reading at a certain time
4 Abbreviations
The following abbreviations apply to this document.
BDS: BeiDou Navigation Satellite System
CCU: Central Control Unit
CMD: Chinese locomotive remote Monitoring and Diagnosis system
MVB: Multifunction Vehicle Bus
TBN: Train Backbone Node
TRDP: Train Real Time Data Protocol
WTD: Wireless Transmission Device
1PPS: 1 Pulse Per Second
