Construction scheme of standardized examination room clock system (examination room clock synchronization system)

Time:2020-11-16

Construction scheme of standardized examination room clock system (examination room clock synchronization system)

Construction scheme of standardized examination room clock system (examination room clock synchronization system)

Beijing Zhun electronic technology official micro enterprise — ahjzsz

[Abstract] the clock system is a large standard timing system. With the popularity of the network, many campuses have built their own campus private networks, and the network equipment and servers used are also increasing. These devices have their own clocks and can be adjusted. However, it is impossible to guarantee that the clocks of all devices and hosts in the network are synchronized, because these clocks will produce errors of seconds or even minutes every day. After long-term operation, the time difference will be more and more big. This kind of deviation has little influence on a single machine, but it may cause unexpected problems in the application of network environment.

1. Overview

With the increasing popularity of campus network, many campus network devices can be adjusted. However, it is impossible to guarantee that the clocks of all devices and hosts in the network are synchronized, because these clocks will produce errors of seconds or even minutes every day. After long-term operation, the time difference will be more and more big. This kind of deviation has little influence on a single machine, but it may cause unexpected problems in the application of network environment. For example, in the distributed computing environment, due to the clock inconsistency of each host, the record time of the same operation in different hosts will be inconsistent, which will lead to the service failure. With the continuous development of various network applications, the requirement of clock is higher and higher, otherwise it will cause many problems.

The campus is composed of classrooms, offices, libraries and other places. The clock information of each place is inconsistent, and the work of teachers and students can not achieve the highest efficiency. In ordinary work, it may have little influence. However, due to the inconsistency of clocks in key examinations, students can’t test out the real level, and the teaching performance of the classroom can’t be evaluated, which has a great impact.

2. System equipment composition

The network clock system consists of satellite signal receiving antenna, NTP satellite clock server (NTP network master clock), network switch, NTP network slave clock, transmission channel (network cable), management software, etc. The system structure is shown in Figure 1.

 

Standard clock

2.1 satellite signal receiving antenna

Satellite signal receiving antenna is composed of satellite mushroom head and antenna with appropriate length, which can provide satellite real-time synchronization signal to satellite clock server (network master clock).

2.2 satellite clock server (network master clock)

The satellite network master clock in the clock system is a dual machine backup device, one of which is the main source of the system time signal, and the other is used as the equipment backup of the whole clock system in case of emergency failure. The LCD display screen of satellite master clock can display the time information of year, month, day, hour, minute and second and the current number of GPS Beidou satellites. The clock system consists of two high stability satellite network master clocks, satellite receiving antenna, antenna bracket, client software, etc;

The multi-channel network port of satellite network master clock can provide standard time signal to digital NTP network slave clock of classroom and office, as well as server monitoring host of campus broadcast system, security system, smart classroom system, intelligent library system, fire alarm system, campus card system, campus information management system and other subsystems.

2.3 NTP network slave clock

Network slave clock (i.e. time synchronization display screen) is installed in classrooms or offices, libraries, corridors, security monitoring rooms and other important places that need to display time.

The network slave clock is digital. It can display time, hour, minute, second, year, month, day, week, hour, minute and second. It can be ordered according to the actual needs of the site. The network slave clock will automatically send the time synchronization signal request, and the satellite clock server (network master clock) will automatically respond and realize the time synchronization after receiving the slave clock request.

The network slave clock adopts frosted PC panel, anti glare and no glare; the ultra-thin metal shell design, electrostatic spraying; the Chinese characters self luminous and integrated with the number.

2.4 transmission channel

The transmission channel between satellite network master clock and NTP network slave clock can be managed by class 5 and 6 network cables, and all equipment adopts standard RJ45 network port.

2.5 management software

The management software can be installed on a high performance computer to monitor the running state of the clock system in real time through the network transmission channel.

The management software can check the operation status of any network slave clock in the clock system, and carry out necessary operations (proofreading, stop, reset, time tracking, time setting, etc.) of any network slave clock in the clock system. When the system fails, it can accurately record the fault time and fault location, and can easily view and maintain, and provide accurate data.

3. System function

The basic functions of the clock system are as follows:

3.1 synchronous proofreading

Through the satellite signal receiving antenna, the system continuously receives the time code and related code sent by GPS / Beidou satellite, analyzes the received data, and judges whether these data are true and reliable. If the data is reliable, it will be adopted by the satellite network master clock. If the data is not reliable, it will give up and continue receiving next time.

Network slave clock is an independent display unit, which can run independently without satellite network master clock. At the same time, it can actively request the standard time information of satellite network master clock, and the network master clock can check the real time. In order to ensure that the received information is true and reliable, the network master clock strictly analyzes and judges the received request information to eliminate interference information.

3.2 time display and adjustment

The time of digital network slave clock adopts the optional mode of “hour, hour, minute, second, month, day and week”. When the time is adjusted, the network slave clock sends out the calibration request, and the satellite network master clock immediately sends out the accurate time information to adjust the slave clock time after receiving the request.

3.3 providing time signals for other systems

Satellite network master clock is equipped with 4-way NTP network interface (RJ45), and each network port has independent MAC address, which is physically isolated from each other and does not affect the work of each other. It can always be prepared to provide time synchronization signal for campus network and other subsystems. The main systems include: broadcasting system, security system, smart classroom system, smart library system, fire alarm system, campus card system, campus information management system, campus computer server, etc.

3.4 system monitoring function

The computer system for management and monitoring of clock system is set in the control center, which has the function of self diagnosis, and can be used for fault management, performance management, configuration management, safety management, etc.

The management computer in the center can detect the operation status information of the slave clock equipment, display the detected fault status, reflect the status of each module in the system in real time and in detail, and can control the whole system clock point-to-point (reset, stop, proofreading, time tracking, etc.).

When the system fails, it can send out sound and light alarm, indicate the fault position, transmit the fault alarm synchronously, provide it to the staff in the duty room, and record and print the fault.

3.5 system scalability

When the system is expanded, the network master clock in the center can be expanded in real time through the expansion equipment to facilitate the addition of network slave clocks at each station.

3.6 distributed control

The system adopts distributed control function, that is, distributed system. The central network master clock and network slave clock are connected with each other through five types and six types of shielded network cables. They are relatively independent in the whole system, and the failure of any part will not affect the operation of the whole system.

4. System configuration principle

The campus consists of classrooms, offices, libraries, weak current security control room and other places.

The installation mode and size of the clock can be determined according to the installation position. We recommend the size, display content and installation location of satellite network master clock and each slave clock. Refer to the recommended configuration table:

Machine room / main control room Hr-901gb master clock: uses um220-iii-l (Hexin satellite communication) GPS + Beidou dual in one satellite time service module as time source, outputs 4-channel NTP network ports for time synchronization of all sub clocks and computer network, local area network timing accuracy of 1-10ms, LCD display real-time display of Beidou satellite number, GPS satellite number and current time information, output 4-channel serial port physical interface, built-in time-keeping module When the satellite is lost, the module still provides accurate timing service (the time keeping accuracy is up to 0.3s/d), 1U standard rack type design, client software, 30m antenna and bracket, antenna arrester, screw and other accessories;

classroom Hr-xs100 digital network slave clock: single display content: hour, minute, second (red 5-inch digital tube); external dimension: 77 * 18 * 5cm; interface: NTP network port and network master clock automatic synchronous timing; power supply 220; travel time accuracy: 0.01s/day; environmental requirements: – 20 ℃ ~ + 65 ℃; MTBF: ≥ 90000 hours; 1. High brightness digital tube, long life; 2. Frosted PC panel, anti glare, no glare; 3 Ultra thin metal shell design, electrostatic spray;

office Hr-xs200 calendar digital network slave clock: single side display content: month, day, week (red 2.3 inch digital tube) hour minute second (red 5 inch digital tube); overall dimension: 77 * 29 * 5cm; interface: NTP network port and network master clock automatic synchronous time calibration; power supply 220; travel time accuracy: 0.01s/day; environmental requirements: – 20 ℃ – + 65 ℃; MTBF: ≥ 90000 hours; 1. High brightness digital tube, long Life; 2. Frosted PC panel, anti glare, no glare; 3. Ultra thin metal shell design, electrostatic spray;

 

library Hr-xs200 calendar digital network slave clock: single side display content: month, day, week (red 2.3 inch digital tube) hour minute second (red 5 inch digital tube); overall dimension: 77 * 29 * 5cm; interface: NTP network port and network master clock automatic synchronous time calibration; power supply 220; travel time accuracy: 0.01s/day; environmental requirements: – 20 ℃ – + 65 ℃; MTBF: ≥ 90000 hours; 1. High brightness digital tube, long Life; 2. Frosted PC panel, anti glare, no glare; 3. Ultra thin metal shell design, electrostatic spray;

Computer room control room Hr-xs200 calendar digital network slave clock: single side display content: month, day, week (red 2.3 inch digital tube) hour minute second (red 5 inch digital tube); overall dimension: 77 * 29 * 5cm; interface: NTP network port and network master clock automatic synchronous time calibration; power supply 220; travel time accuracy: 0.01s/day; environmental requirements: – 20 ℃ – + 65 ℃; MTBF: ≥ 90000 hours; 1. High brightness digital tube, long Life; 2. Frosted PC panel, anti glare, no glare; 3. Ultra thin metal shell design, electrostatic spray;

Other offices Hr-xs200 calendar digital network slave clock: single side display content: month, day, week (red 2.3 inch digital tube) hour minute second (red 5 inch digital tube); overall dimension: 77 * 29 * 5cm; interface: NTP network port and network master clock automatic synchronous time calibration; power supply 220; travel time accuracy: 0.01s/day; environmental requirements: – 20 ℃ – + 65 ℃; MTBF: ≥ 90000 hours; 1. High brightness digital tube, long Life; 2. Frosted PC panel, anti glare, no glare; 3. Ultra thin metal shell design, electrostatic spray;

5. System summary

The clock system not only facilitates the accurate timing of enterprises and institutions, but also greatly improves their work efficiency. The improvement of efficiency means the improvement of social public services. The strong attention of enterprises and institutions to time is the witness of their service and efficiency consciousness.

With the establishment of big data in various units, the number of network equipment and servers is increasing. When network administrators view the logs of many network devices, they often find that the time is different. Even if the time is set manually, there will be time errors due to time zone or daylight saving time. After the restart of some layer-2 switches, the clock will return to the initial value and the time needs to be reset. For the core network equipment and important application server, they sometimes need to work together, so the unified accuracy and reliability of time is particularly important.

At the same time, the clock system has the industry-leading environmental protection performance, leading the trend of urban green office. With the accelerating pace of modern people’s life and the popularization of network, the demand for time accuracy is also higher and higher, especially the current airports, railways (subway and railway stations), hospitals, schools, government agencies, enterprises and institutions just meet their needs and solve real problems for them.