Unified, harmonized standards significance clock system for digital management of the school and school departments, major examination room.
First, the school needs a standardized exam clock
"National Education Examination standardized test sites specification" clearly stipulates that the examination of domestic demand set the clock, without affecting the normal examination conducted for the candidates to provide a time reference. According to the Ministry of Education plans to be in the country on a unified platform, standard GMT information is based on the full realization of the National Education Examination online inspection, two-way audio integrated command and examination affairs management. Currently various provinces and autonomous regions have gradually started construction under the unified arrangements and technical specifications of the Ministry of Education requirements.
In practical applications, the campus network devices and servers are increasing, there is no guarantee that time is synchronized clocks because they will have a few seconds every day, even a few minutes error, long run time difference will become increasingly large, this misalignments in the microcontroller impact is not big, but in the application under the network environment may lead to unexpected problems. For example, a distributed computing environment. Since each host time inconsistency will result in the same operation a few inconsistencies in the way different time host, it will cause the server can not be normal. For example, the campus network, there are a lot of network equipment, servers and host them carrying the campus billing, maintenance, management and other functions, accuracy, time requirement is relatively high. It is necessary to build a school network clock system to ensure the transfer of information between network devices to ensure high degree of unity in time.
Second, the composite clock system design school guidelines
School composite clock time synchronization system design must follow the following points:
1, earnestly implement the state has promulgated and implemented the relevant "norms", "Standard", the design does not deviate from the track and standardization, in order to ensure that the design of the level and quality.
2, the system design should be based on "reliable, practical, advanced and economy" principle.
3, under the premise of efforts to meet the functional requirements of the project cost and reduce maintenance costs.
4, the system is simple to operate, reliable, easy to maintain and extend the software has the ability to improve.
5, the system meet the site conditions and the environment
Third, the school exam school automatically synchronized clock constitution
Real clock that is standardized examination school composite clock time synchronization system, in fact, a simple configuration master clock (time server) and the number table clock (digital display clock), the master clock is typically 1U standard rack or standard 4U time server, clocks that display minutes and seconds, day of week, temperature and humidity clock. Mainly bus control (RS232 / 485, etc.) and network control (NTP) based. Regardless bus or network functions to achieve a unified time information, computers, servers, clocks, 10,000 network devices are based on the time master clock signal is sent as a reference.
Fourth, schools composite clock system master clock selection
Master clock is a reference clock time synchronizing means source school system, the system clock essential equipment. Standard time signal received master clock standard GPS Compass when satellites are lost, may switch to an internal or external time source oscillator as a standard reference clocks continue to other equipment under the normal timing. In practice, only the master clock to the LAN, set ip in the web management page, clocks and other computer equipment at the time of grant ip points to the need to grant master clock time.
The choice of the master clock, is carried out primarily determined based timing mode. School system clock synchronization devices in the choice of the master clock to a network time service-oriented way, we need to consider the following:
a. time source master clock (GPS / Compass / NTP / IRIG-B / PTP / CDMA, etc.)
When the interface is granted b master clock (NTP).;
. C determines the number of output interface (in practice to isolate the physical LAN into optional 10M / 100M / 1000M);
. D length of the antenna (antenna particularity material, we generally subject to a fixed size, according to the actual situation, 30m / 50m / 70m / 80m / 100m / 150m / 200m, etc.);
e Annex selection: arrester, OCXO, rubidium, dual power, the reference time source or the like.
As shown in FIG topology we standardize the construction of schools examination system clock is selected ntp dual-mode network time server and simultaneously receives gps Compass, i.e. input 1 ntp province or city EDB as an external reference time source, output 4 ntp when network ports are to meet the entire campus network physical isolation 4 million units on the network equipment grant, including the suspension of the examination room classroom clocks, clocks monitoring system of computers, servers, office, teaching equipment and network cameras.
Some actual school and put into two NTP master clock that is actually a network server to achieve redundancy, the purpose of technical reserves. ntp network time server synchronization are supported Xi'an heartbeat detection, two master clock or an actual NTP network server contains multiple network interfaces, both of which can be set to the same IP, connected at the same time, when for some reason a when the fault can not normally granted, heartbeat detection may be immediately detected, a seamless switch to another one, so that the reliability of the timing when the timing system is very high.
Five schools composite clock system clocks selection
Usually the master clock and slave clock with them from using the timing can be divided into two categories namely ntp network clocks and 485 clocks, from the appearance of slave clocks can be divided into digital and Analog clocks, each school can choose according to actual needs. In addition to the need to pay attention to the following points when purchasing:
. A determined display the contents of the sub clock (year, month, day, hour, minute, second, week, temperature, humidity);
. B clocks determined size (actual size or diameter is determined according to digital);
. C determine the color of the LED (red-based standard, recommended to choose the visual appearance red);
d. Single-sided clocks to determine the (school corridor, recommended to choose double-sided, other locations depends on the situation).
- Conclusion
At present, Xi'an synchronous clock electronic production of standardized examination system at colleges and universities across the country have been put into use, its excellent product quality and customer service has won enthusiastic praise, hope that in the coming days to be able to synchronize more schools, examination provide clock synchronization service.
