Rail network an important part of the system clock (composite clock system)
rail network an important part of the system clock (composite clock system)
Subway clock system is one important part of the rail transport system, its main role is as the control center dispatchers, station attendant, departmental staff and passengers to provide a unified standard time information for subway systems and other communications systems ( ) time signal to provide a unified signal, AFC, ISCS, ACS systems.
Set the clock system to ensure accurate timing subway, improve operational quality of service has played an important role.
1.2 Clock system features
high accuracy
地铁时钟系统中的一级母钟和二级母钟均采用高稳定、高精度的晶体振荡器，以确保系统高稳定性、高精度。
系统能够接收来自GPS/北斗卫星的标准时间信号，经母钟处理后发送至系统的各个部分，从而实现整个时钟系统长期无累积误差运行。
High reliability
地铁时钟系统的控制中心一级母钟和车站/车辆段二级母钟的关键部件都采用热备份，当主单元出现故障时，能够自动切换到备用单元，保证了系统的高可靠性。同时时钟系统还采取了“节点功能逐级延续”的运行方式，具备降级使用功能，当前级节点设备出现故障时，本级节点设备仍能正常工作；同级节点发生故障互不影响。
系统采用分布式结构、闭环控制、掉电保护、故障自诊断、故障隔离技术、软硬件冗余措施、保护接地、严格筛选元器件、抗电气干扰及电磁干扰、提高了系统的可靠性。
Scalability
系统采用分布式结构方式，充分考虑了地铁的工程的扩建(延长线)。时钟系统的扩展可以通过保持软件不变，硬件只需少量增加控制单元的方法实现。
Easy compatibility
系统由标准化的软件及硬件组成，用户可按照自己的需要灵活配置。系统软件能够适应计算机技术的急速发展，采用目前最流行的语言编译，运行在主流的操作系统平台上。为保证系统持久可靠地运行，设计时充分考虑到地铁/轻轨各种强电设备对时钟系统的电磁干扰，各项指标均须符合IEC61000系列的要求，并取得第三方设备检测机构签发的标明各项电磁性能合格的检验报告。
Ease of maintenance
系统设计时在关键设备的关键部位设置了用于维护和检测的测试点；整个时钟系统采取了故障隔离、故障自诊断技术和自动报警措施；标准化高集成元器件的选用、具有互换性板卡的模块化设计（相同规格的设备、接口板都具有互换性）；一级母钟、二级母钟的控制板均支持热拔插技术，使得系统维护极为简便快捷。
Easy adaptability
传输通道可以采用SDH、ATM、OTN、PCM等多种方式实现。
Comprehensive monitoring
时钟系统的一级母钟以及二级母钟均可实现点对点监控、发现故障自动报警。一级母钟的主备母钟既可自检测也能互相检测，以及时发现系统故障，并进行主备母钟自动转换。
二级母钟可以通过切换按键显示备用二级母钟以及所带子钟的工作状态。
维护管理终端除了监控各个子钟运行情况外，还可以监控到控制中心一级母钟、各车站、车辆段二级母钟接口板的工作状态，并可控制一级母钟的主备母钟自由切换。
1.3 Clock basic functions described
subway construction system clock and a clock master station, depot two secondary master clock provided by the control center, the following basic functions:
1.3.1 Synchronization proofreading
synchronization proofreading under normal circumstances: when a master device receives an external clock GPS / Beidou automatic correction standard time signal (standard time signal reception can be public information transmission network system, such as Shanghai subway system) to keep pace. While generating accurate time code synchronization, a transmission channel to each station, two master clock transmitted through the depot, unified calibration secondary master clock;
Secondary master clock system receives a master clock signal issued by the standard time code, synchronized with the master clock at any time, and produces an output time of the drive signal for driving all the sub-site clock, and to the station back to the center apparatus work information subsystem.
Proofreading synchronization abnormal conditions: a master clock when not receiving GPS / Beidou standard time signal (or a transmission channel GPS / Beidou receiving unit fails), capable of generating a master clock to synchronize itself accurately with high accuracy oscillator time code, and the depot station to each secondary master clock synchronization proofing.
In the case of secondary master clock interrupt transmission channel, it is possible to work independently, with its own precision oscillator generates a drive signal for driving the time information of the station clocks, clocks so that the area can be uniform normal time display.
Transmission channel or other recovery in a case where synchronization Proofing: secondary master clock or slave clock time after receiving back a master clock signal should have automatic correction function.
1.3.2 Time display
master clock display: "year, month, day, week (Chinese characters), hours, minutes, seconds, milliseconds," full time stamp information;
Clocks display:
Ø 日历数字式子钟：“年、月、日、星期（中文字）、时、分、秒”；
Ø 数字子钟：“时：分：秒”；
Ø 模拟式子钟“时：分”。
1.3.3 standard time signal to another system
master clock synchronous multiplexing apparatus is provided with an output interface time code, it is possible to provide millisecond standard time signal to each of the other systems in the entire second time.
1.3.4 clock system management
clock management system has the following functions in the system management terminal clock by setting the control center:
Monitoring and display
监控终端能够检测地铁时钟系统主要设备的运行状态，对系统的工作状态、故障状态进行显示，并能够对全系统时钟进行点对点的控制，其主要监控及显示的内容包括：
Ø standard operation state signal receiving means;
Ø operating state of the signal processing unit;
Ø master clock, secondary master clock, the working status of each sub-clock;
Ø operating state of the transmission channel;
Ø system-wide clock control system (speed up, slow down, reset, proof, when the recovery and the like);
Ø common troubleshooting information, and lists helpful information.
Fault Management
监控终端应能对故障状态及故障产生的时间进行存储记录和打印。系统出现故障时，监控终端能够发出声音报警，并可在监控终端主界面上显示主要故障内容及设备位置。声音报警信号能通过手动操作去除。同时故障信息能够通过10/100M以太网传输到集中网管，便于地铁通信系统的集中管理。
Security Management
Ø User management: users to create, login authentication and automatic logout & operations such as user management functions;
Ø network monitoring: to see the information, any data can not be modified;
Ø network maintenance: can modify the general maintenance of the required data to the database but can not be modified;
Ø Network Management: Can modify any data in the database;
Ø NMS record: were all to sign, operators content real-time monitoring, recording and storage, monitoring process with documented way. The files can be viewed, printed, can not be deleted.
2. The system clock composition
2.1 Total FIG.
2.2 Overall Structure
subway time system consists of a master clock control center, a network management device, each station, depot secondary master clock, clocks and so on.
2.2 System clock function described
master clock control center receives GPS / Beidou standard time signal, while generating accurate time code synchronization, through the transmission system to each station, two master clock transfer depot, two calibration unified level master clock. A master clock while the center of each drive control clocks.
各车站、车辆段的二级母钟，接收一级母钟的校时信号用于驱动本站所有的子钟正常工作。
子钟接收二级母钟发出的标准时间码驱动信号，进行时间信息显示。
The system clock is provided independent monitoring terminal via the operating-state data channel clock line real-time monitoring system, the implementation of fault location, alarm, and by 10 / 100M network interface device centralized network transmit alarm information to the communication terminal for centralized management.
2.3 clock distribution system equipment
2.3.1 Control Center
clock system should be installed in the control center of the following devices:
Ø mounting a master clock, and an output interface devices and other equipment in the control center communication device chamber;
Ø installing digital calendar clocks in dispatching hall;
Ø installing digital calendar clocks in office operations;
Ø In the equipment room and other related office space, etc. to install digital slave clocks;
Installation Ø network management device and the printing device through the network output chamber.
2.3.2 Station
-time systems should be installed at each station about equipment:
Ø mounting secondary master clock, and an output interface devices and other devices at the station communication equipment room;
Ø management space station (car control room, Master room, communications room, ticket room, shift change room and station staff room, etc.) installed in the digital slave clocks;
Ø installation of digital clocks in the call center Station Hall public areas;
Ø station platform level due to the passenger information system (PIS) display time information, so that no separate clocks.
2.2.3 Depot
-time systems should be installed at the depot equipment:
Ø mounting secondary master clock, and an output interface devices and other equipment in the communications room depot;
Ø installing digital calendar clocks in the signal tower control room and library parking train inspection operation duty room;
Ø device space management (communications, signal equipment room) mounted digital slave clocks.
Ø in the management space (duty room and room management, etc.) to install digital slave clocks.
2.4 Equipment
2.4.1 master clock
master clock control center installed in the communications room, the internal configuration shown in Figure 1. Master clock mainly includes the following modules:
Ø main and backup GPS standard time signal receiver;
Ø master, standby master clock;
Ø branching output interface box;
Ø NTP server module;
Ø power module
1, a block diagram of a master clock
2.4.1.2 The main function of a master clock
一级母钟接收来自GPS/北斗卫星发出的标准时间信号经解码和比对后校准自身精度，输出时间信号。标准时间信号经传输网络发送至各个车站/车辆段的二级母钟。一级母钟各模块功能介绍如下：
GPS standard time signal receiver: GPS standard time signal acquisition and accurately accumulated error protection system operating time. Receiver uses RS-422 interface communication with a master clock. Standby GPS standard time signal receiver with self-switching function.
Branching output interface box: a master clock to achieve the main and standby master clock and transmission subsystem and the branching output interface conversion, and the standard time signal may be provided to monitor its operational status is secondary master clock of each station, other NTP server and a communication system standard time signal output interface.
其接口形式采用标准的RS-422和RS-485接口。
NTP server: receiving a control center master clock time signal or GPS emitted through the computer network system, using TCP / IP or UDP protocol Network Time Protocol, server time, a client within the synchronous network and associated computer systems.
Power control box: double backup mode to provide a 12V DC power to the master clock, and an output interface splitter box.
2.4.1.3 performance of a master clock
Ø accuracy: the standard time signal deviation: ≤1 ms;
Ø Load: secondary master clock: 100;
子钟：200个；
标准时间信号：20路（只发不收）；
Ø maximum driving distance: 1219 m;
Ø Stability: standby signal processing unit arranged in dual mode systems, having self and mutual check function, and the master can be implemented automatically or manually switch between backup unit;
Ø Reliability: a hot backup, a master clock of the master, standby master clock can be switched manually and automatically;
主母钟故障立即自动切换到备母钟，全面接替主母钟工作；
当主母钟故障解除立即自动由备母钟切换回主母钟工作；
满足25年×365天×24小时连续不间断工作。
2.4.2 secondary master clock
secondary master clock provided in the respective stations and depot communications room, secondary master clock configuration diagram shown in Figure 2, mainly includes the following modules:
Ø master clock time signal receiving means;
Ø main and backup secondary master clock;
Ø branching output interface box;
Ø power module;
FIG 2 secondary master clock internal configuration of FIG.
2.4.2.1 secondary master clock main functions
of each of the two stations and depot master clock under normal conditions, a standard time signal received via the transmission system sends the master clock, eliminating accumulated error, synchronized with a master clock, this station and / depot all clocks standard time signal transmission, while the respective sub-time clock within their respective regions, and the operation state code transmitted back to the master clock.
当一级母钟或传输通道出现故障时，二级母钟自动报警并用自身晶振发送时间信号给子钟。
2.4.2.2 performance of the secondary master clock
Ø Accuracy: deviation secondary master clock and master clock output time: ≦ 20 msec.
Ø Load capacity: clocks: 200;
Standard time signal: channel 10 (only send received)
Ø clocks drive maximum distance: 1219 m;
Stability Ø: hot backup mode;
Ø Reliability: the interfaces partial failure does not affect the normal work of the whole system;
能够保持365天×24小时连续不间断工作。
2.4.3 slave clock
clocks the received standard time signal from a master clock or the secondary master clock display uniform time. Clocks can be classified as follows:
Ø 根据工作模式分为：数字式子钟和指针式（模拟式）；
Ø 根据观结构上分为：单面和双面类型；
Ø 根据显示方式分为：日历数字式子钟和时分（秒）指针式子钟；
Ø 根据安装方式分为：壁挂式子钟和嵌入式子钟。
2.4.3.1 analog clocks internal structure
2.4.3.2 internal configuration diagram of the digital clocks
2.4.3.3 illustrations of various clocks
2.4.3.4 clocks distribution
performance 2.4.3.5 of clocks
Ø Accuracy: and a master clock or two master clock time offset: ≤10 ms;
Ø Reliability: the integrated circuit built-in clock and a rechargeable battery, power failure can continue to maintain real time,
来电后子钟能自动刷新和显示正确时间。
2.4.3.6 manufacturing process requires clocks
Ø clock cases: a metal material, the surface after pickling, phosphate treatment and galvanizing treatment spray, uniformly colored, solid, not color.
Ø mounting parts: rust meet the requirements surface treatment, surface coating is smooth, uniform color; surface electrostatic spraying before pickling, phosphate treatment and galvanizing treatment, the outer surface reaches stage 2 GB, the inner surface of grade 4 GB, spraying matt surface, a uniform color; surface roughness of not more than 1 mm in each square meter area, the surface knuckle no wrinkles, cracks, burrs, weld marks, etc., surrounded by the slit is consistent, the door open and flexible, without jamming. Before fitting, the inner surface of the closure structure is also necessary to spray or rust treatment process in line with SSPC quality standards.
Other Ø: a shock, dust, moisture, rain and other functions to ensure that no deformation of the transport storage, installation and use, without damaging, protection IP≥65.
2.4.4 Network management terminal clock system
main function 2.4.4.1 network management terminal
clock terminal monitoring and management system that is monitoring computer, includes a self-diagnostic function, system performance management, configuration management, fault management, security management. It is through a standard RS-232 interface is connected with a master clock, with centralized maintenance functions and self-diagnostic function.
系统出现故障时能够发出声光报警，指示故障部位。同时，故障信息能够传输到集中告警终端，以便与地铁通信系统的集中管理。
Which enables remote network alarm, timely and relevant information will be transferred to the device manager is not the fault site communication tool.
2.4.4.2 display network management terminal
maintenance management terminal capable of real-time detection equipment operating status main subway system clock of the system working status, fault status display, printing, archiving, and the ability to control the clock on the full range of point to point, the main content monitoring and displays include:
Ø master, standby operation state of the GPS;
Ø master, working condition and working condition of the apparatus the signal processing unit of a master clock;
Ø station / depot secondary master clock, each operating state of the sub clock;
Ø operating state of the transmission channel;
Ø control of the system clock line;
Ø basic troubleshooting principles help;
Ø fault conditions and time of printing and storing records.
Main system clock device power consumption 2.5
Device Name
unit
Stand-alone
Power (W)
A master clock
station
50
Secondary master clock
station
50
Calendar Digital clocks
station
50
Digital slave clocks
station
20
Main and backup GPS standard time signal receiver
station
10
NTP server module
station
20
Network management terminal
station
250
2.6 System Clock Interface
Interface 2.6.1 transmission system
若标准时间信号的来源是公用信息系统传输网，接口可采用网线型RJ45也可采用标准RS422接口；若标准时间信号来源是GPS/北斗卫星信号，采用标准RS422接口。
A master clock:
一级母钟为传输系统提供RS422接口，数量必须保证系统功能及扩展需求。
Secondary master clock:
在各车站/车辆段由传输系统提供1路RS422接口，连接二级母钟，实现控制中心一级母钟与车站/车辆段二级母钟的联机通讯。
2.6.2 Interface with other systems
控制中心一级母钟设20路标准时间码输出接口，能够在整秒时刻给地铁控制中心传输系统、无线系统、广播系统、公务电话系统、专用电话系统、广播系统、乘客信息服务系统、电视监视系统、信号系统、售检票系统、防灾报警系统、设备监控系统、电力监控系统、集中维护系统等系统提供标准时间信号。
2.6.3 Time clock system standard common interface protocol
Ø Output Interface: Standard RS-422 port
Ø Baud rate: 9600bit / s
Data Bit Ø: 8
Start bit Ø: 1
Ø Stop bits: 1
Ø Parity: there
Ø Work: Asynchronous
Ø Data format: (ASCII string of 21 characters)
Ø maximum transmission distance: 1219 m
2.6.4 system clock signal and the system interface protocol
clock system provides a standard time signal is a signal system, according to the requirements of the signal system, the control station and the central master clock / depot secondary master clock are provided in line with channel 1 "NMEA0183" the standard time format interfaces, the interface type RS-422.
2.6.5 Interface connections
at the rear of the control center of a master clock control cabinet with a standard time output interface box 20 provides an interface deck (two lines TX +, TX-) provides the standard time signal to other system devices; 1 deck two lines (TX +, TX-) provides a single standard time signal provided to the NTP server.
Clock system to other systems (transmission systems, wireless systems, radio systems, business telephone systems, dedicated telephone systems, broadcast systems, passenger information service system, video surveillance systems, signal systems, fare collection systems, fire alarm systems, equipment monitoring system , power monitoring system, centralized maintenance system, etc.) provides the standard time, simplex communication mode, using 2-wire communication cable.
时钟系统的一级母钟与二级母钟的信号传输提供40路路标准RS422接口，其中17路作为预留。采用双工通信模式，采用4线通信线缆。
2.7 cable clock system
power supply line: Use RYY3 * 1.0mm² (circular, strong tensile strength, the core 3, the cross-sectional area of 1 mm2) for supplying a clock type cable system equipment.
Signal lines: the master clock and the slave clock can correspond shielded twisted pair UTP are used in LSZH.
3 clock system design requirements
3.1 clock subway system design specifications
3.1.1 system clock technical specifications
detailed in Annex 1: "GB 50490-2009 urban rail transit technical specifications" (PDF) clock system parts.
3.1.2 clock system design specifications
detailed in Annex 2: "GB50157-2003 Design Code metro" (PDF) clock system parts.
3.1.3 Quality Acceptance
see Annex 3: "GB 50382-2006 urban rail transit communication engineering Quality Acceptance" (PDF) clock system parts.
3.2 clock system of lightning and other
mine:
Ø GPS antenna receiver is outdoors, isolation measures should be taken to the mine;
Ø clock power system equipment are varistors, surge acts of;
Overvoltage Ø cable using a gas tube protector; overcurrent protection device capable of using a cable self-healing;
Ø system clock transmission interface chips are used in anti-lightning chip;
The security system clock Ø grounding resistance less than 1 ohm.
Clock design and production:
Ø comply with ISO and IEC standards, and the SMPTE / EBU time code standards.
Ø mechanical structure easy installation and maintenance, ease of expansion, has sufficient mechanical strength and hardness
Ø installation complete accessories
Ø assembled apparatus has shock resistance, to ensure that no deformation, no damage.
