The wall washer series are professionally used in outdoor parks, building exterior walls, amusement parks and other places. Add color and effect to the original ordinary buildings, waterproof lamp body design, no fear of rain. Especially when used around the exterior walls of hotels and buildings in tourist areas, it can give people a very good experience. When used on the stage, it can bring beautiful color effects to the stage.In addition to the color control effect, this product also has a point control function, which can produce more vivid dynamic effects, which is a good choice.
Wall Wash Lights ,Led Wall Washer Light,Led Wall Washer,Wall Washers Guangzhou Cheng Wen Photoelectric Technology Co., Ltd. , https://www.leddisplaycw.com
Time information (year, month, hour, minute, second) of various communication equipments or computer equipments on the communication network is limited to a sufficiently small range (for example, 100 ms) based on UTC (Coordinated Universal Time). This synchronization process is called time synchronization.
In general, the most widely used time synchronization is a computer on the Internet. The computer clock is used to record event time information such as E-MAIL information, file creation and access time, database processing time, and the like. The clock is also used to control the operation of the backup, automatically build a compiler for the design to check if the file has changed and other applications. If the computer clock is inaccurate, many of these applications will not work properly. Time-sensitive computer systems, such as financial industry servers, EDI, large distributed commercial databases, aerospace control computers, etc., also require highly accurate time information. The time display system of the transportation industry, such as the subway timetable display system and airport schedule display system, may affect the travel of passengers if the deviation is large.
CDMA base stations need UTC information. Relying on the GPS satellite time synchronization CDMA system, the time synchronization between the base stations is based on the common CDMA time scale, and the time standard is synchronized with the UTC time by receiving the GPS timing. The BTS needs absolute time to acquire the CDMA signal sent from the MS. In soft handover, a mail order mismatch may occur in the selector due to the BS message path queue delay. To prevent this mismatch, all BTSs and BSCs must be synchronized in time.
The time synchronization function is also used in phone billing because of the presence of multiple operators and the existence of time-divided rates. The loss of bills caused by inconsistent billing between networks can be reduced or even eliminated by adopting time synchronization. For example, when telecom and Unicom communicate with each other, they are billed through the gateway office. If the billing starting point at the telecommunication side is 20:58 (before half time), and the billing starting point at Unicom is 21:01 (after half time), then There will be errors in the bills for telecommunications and Unicom billing. The usual practice is to discard the bills and the losses will be borne by the operators of both parties. If the absolute time (TOD) provided by BITS can be received on the exchanges of both parties, the billing error of both parties can be controlled in the order of milliseconds, thereby fundamentally avoiding the difference in bills. Even if only one of the exchanges can receive the TOD, the party can take the arbitral position in the billing decision and eliminate the loss for oneself. Therefore, the TOD solution is a synchronous new technology that operators pay close attention to.
NMS alarms and logs also need to accurately record the exact time of events and alarms for fault and performance analysis. For example, the alarm time generated by the NMS may not be the exact time when the switch actually generated an alarm. In addition, when the network management center adopts multi-point logging, if the nodes of the network are not synchronized in time, log records will be confused. If you need this information to quickly and accurately locate the fault, accurate time is essential.
Second, UTC time reference acquisition
The standard time scale adopted by most countries in the world is based on the astronomical time at which the Earth rotates and the coordinated universal time-of-day UTC based on the atomic oscillations of the atom. UTC time is spread through many channels, including wireless and satellite navigation systems, telephone modems and portable timers.
The time reference of the satellite navigation system is given by the ground time reference source of each country. Therefore, using the GPS GLONASS BDS receiver can easily obtain the UTC time.
In order to achieve the dissemination of time information and ensure the propagation accuracy, a distributed network time protocol is needed. These protocols ensure that the time synchronization network element device correctly reads the server's time, transmits the readings to one or more customers, and adjusts each customer's time as needed. These protocols include Network Time Protocol (NTP), Digital Time Synchronization Protocol (DTSS), and so on.
Third, the dissemination of UTC time
UTC transmission time information, usually wireless transmission (high-frequency or low-frequency radio signals), wired transmission (DCN, PSTN, DDN, etc.), In general, the telecommunications network uses wired transmission to solve the UTC time spread.
With the development of computer networks, the Network Time Protocol (NTP) protocol has become a member of the TCP/IP protocol family. Currently, the time server (NTP) installed on the internet with NTP software provides a time service benchmark to its client computers. The primary time server (NTP) almost always obtains UTC absolute time information from the GPS receiver (using the RS-232 interface). The low-level time server (NTP) obtains UTC time from the upper server through the TCP/IP-based DCN network. All client computers that require time acquire the UTC time information from the specified time server (such as the Shanghai Ruicheng K801 NTP network time server, reference: http://) by installing the NTP client program to calibrate its own current Time information.
In 1998, the Internet's NTP protocol had more than 230 primary time servers (NTPs) that were synchronized via wireless, satellite, and modem, and far more than 100,000 secondary servers and clients. In addition, there are thousands of private networks in government, communities and institutions. They act as a sub-tree or subnet in the synchronization network, where the primary server acts as the root and the secondary servers and clients are growing.
The NTP protocol is used to provide TOD, which is suitable for users with DCN networks. The investment is the lowest, and the accuracy meets the requirements of billing, e-commerce, and network management.
Fourth, time synchronization network program
Inter-office time synchronization
The inter-office time synchronization network structure includes a stratum 1 (secondary time server), a stratum 2 (secondary time server), a stratum 15, and a stratum 15 time server (NTP).
The superior and inferior time servers (NTP) prefer to use the DCN network. Normally, there are fixed routes with fewer transfer times between the upper and lower level time servers (NTP), and the transmission distance is not particularly long. Therefore, this method has the lowest investment and performance. Good, easy to install, and maintenance-free features fully meet the basic requirements of second-order accuracy for telecom users and businesses (tracking can achieve accuracy well above 100ms). If you do not have a DCN network, you can also set up a dedicated time synchronization DCN network to send NTP packets, such as DDN private line, PSTN dedicated line (need to use MODEM) or E1 private line. As long as the transmission channel between the servers works stably, it is enough to make the NTP of all levels have millisecond accuracy.
2. Intra-office time synchronization
The computer installed with the client NTP software obtains the UTC time reference from the network time server (NTP) through the LAN of the local area network to calculate the local UTC time information; the client computer can acquire the synchronization information by installing a software program based on NTP or SNTP.
It can be seen that any computer user who can be in the same building as the time server (NTP) is the most efficient way to obtain TOD time through the TCP/IP LAN. Therefore, this method has the advantages of low investment, easy software installation, and high accuracy. , It is the easiest to promote in large quantities.
Computers that cannot be on the LAN LAN can only transmit UTC information through the physical interfaces (such as IRIG-B, RS-232, etc.) of the accessible user equipment.
Therefore, the current NTP protocol is the best choice, which is sufficient to meet the accuracy requirements of most network management centers and communication devices (workstations, servers, maintenance terminals, and switches) on communications networks for alarm, log, billing, and file recording services. There will be no impact on the load of the original data network (generally not exceeding 2% of the total load), and it is convenient to install, use or upgrade.
The time server (NTP) adopts the standard NTP protocol. The interface it provides is also standard. Other synchronized time servers (NTPs) and users do not need to use the same operating system and software as the primary time server (NTP). Provide the standard NTP interface to use the NTP service provided by SYNLOCK. Huawei provides other levels of time server (NTP) software and hardware to provide time server (NTP) software for other WINDOWS-based network management centers or SUN workstations.
The communication network between the time server (NTP) and the synchronization device can use the existing private network, and can also be constructed through various communication networks such as PSTN and DDN.
First, the meaning of time synchronization