1. What wireless network Wireless Bridge,Wifi Wireless Bridge,Gigabit Wifi Bridge,Long Range Wifi Bridge Shenzhen MovingComm Technology Co., Ltd. , https://www.szmovingcomm.com
After 20 years of research, design, manufacture, and users' joint efforts in recent years, joint research has been fruitful. In the 'West-East Gas Transmission', 'South-to-North Water Diversion', 'Three Gorges Water Control Project', Million-kilowatt nuclear power unit, one-million-ton ethylene renovation project, supercritical and ultra-supercritical thermal power unit, oil and gas pipeline transportation, coal chemical industry, large-scale ships, and municipal wastewater In areas such as processing and major engineering equipment and nuclear power, petrochemicals, metallurgy, and power stations, in addition to a small number of high-parameter safety valves and regulating valves that need to be imported, localization of valves has been realized, which has changed the situation in which key valves of major equipment are permanently controlled by foreign countries. . And strive to achieve as much as possible in the short term major projects and key valves to achieve localization, or part of the realization of localization, so that China's valve manufacturing industry in the forefront of the world.
Starting from scratch, accelerating the pace of localization of valves The domesticization of Chinese valves has always been a long way to go. At the beginning, China advocated the localization of valves. It was not plain sailing and met with resistance at all levels. It was more controversial. After the experts of the older generation valve industry and some scientific research departments of the nuclear industry have tackled problems and coordinated efforts, domestically-made ones and resolutely domestically-made ones will try their best to wipe the ball in the localization to save foreign exchange for the country.
The localization of China’s valves was nothing at all, starting from scratch, and starting from localization in nuclear power plants and nuclear chemicals, as well as petrochemical equipment, in the 1980s, the first 600,000 nuclear power units related to engineering key projects were captured, and later When Qinshan Nuclear Power Station was engaged, Ningbo Valve Factory, as a pilot enterprise for the localization of valves for nuclear engineering fittings, contributed to the localization of valves. After the reform and opening up, China increased the localization of valves. With the continuous improvement of the manufacturing technology of the valve industry, many companies used the advanced resin sand molding line to produce casting blanks. The chemical composition of the castings was analyzed by a direct reading spectrometer. Cobalt 60 gamma ray is used to detect defects in castings; forging uses advanced technology such as tire die forging and multi-directional die forging. After entering the 21st century, the pace of localization of the valve has accelerated, and there have been achievements in the localization of major projects.
After issuing the "Several Opinions on Accelerating the Revitalization of the Equipment Manufacturing Industry", the State Council led the equipment manufacturing industry to revitalize in an all-round way. For this reason, the National Development and Reform Commission, the China National Machinery Industry Federation, and the China Association of National Associations and other national authorities have long proposed the plan to gradually realize the nationalization of major equipment and valves during the 'Tenth Five-Year' and 'Eleventh Five-Year' periods, which proposed the realization of millions of kilowatts. The key valves of nuclear power plants and the localization of valves for large-scale ethylene equipments of one million tons were introduced into key technologies and self-developed, and many concessions were given to regulations and policies. As a result, related valve companies seized the opportunity to take the initiative to make the country Localization of valves. Consensus was formed up and down, and localization of valves made gratifying progress.
Significant progress has been made in the localization of nuclear power valves. Key valves of nuclear power plants are important equipment for nuclear power plants. For a long time, they have mainly depended on imports. Foreign countries have always imposed a technical blockade on China in order to earn high profits, which has also become a bottleneck restricting the localization of nuclear power in China. one. The development of domestic nuclear valves started in the early 60s. After decades of efforts, China has formed a large-scale nuclear valve design, experiment, manufacturing, and testing capabilities, and provided a large number of nuclear-level valves for Qinshan Nuclear Power Station Phase I and Phase II construction. It has made important contributions.
Wireless network, as the name suggests, is a way to build a network without relying on network cables, which is mainly achieved by using wireless communication technology. There are two main ways of wireless network (such as 4G, 3G or GPRS) and wireless local area network (WiFi) through mobile communication networks.
2, What wireless bridge
Wireless bridge, as the name suggests, is the bridge of wireless network, which uses wireless transmission to achieve a communication bridge between two or more networks. In addition to having the basic characteristics of a wired bridge, a wireless bridge works in the 2.4G or 5.8G wireless license-free frequency band, making it easier to deploy than other wired network equipment.
From the function to understand the wireless bridge, it can be used to connect two or more independent network segments, these independent network segments are usually located in different buildings, hundreds of meters to tens of kilometers apart, can be widely used in the interconnection between different buildings.
At the same time, according to different protocols, wireless Bridges can be divided into 802.11b, 802.11g and 802.11n in the 2.4GHz band and 802.11a and 802.11n wireless Bridges in the 5.8GHz band.
3, the meaning of wireless bridge 2.4G and 5.8G
2.4G Bridge:
The advantages are low frequency, large wavelength and strong diffraction ability. Simply put, the propagation performance is good, and the propagation path is slightly shielded. Then there is the relatively low cost.
The disadvantage is that there are many devices using the 2.4G band, and the electromagnetic wave signal emitted by the bridge is easily interfered with the signal emitted by other devices, resulting in a decrease in transmission quality. Moreover, it is limited by the transmission bandwidth of the 2.4GHz band itself, which generally does not exceed 300Mbps
5.8G Bridge:
The advantages are high frequency, relatively pure channel, and large transmission bandwidth. The transmission bandwidth starts at 433Mbps and can easily reach more than 1Gbps. It is suitable for scenarios that require high data transmission.
The disadvantage is that the frequency is high, the signal wavelength is short, the penetration is poor, and there can be no shelter during the propagation. The cost of 5.8G equipment is higher than 2.4G, and it is still in the popularization stage.
Wireless bridge transmission system is usually composed of two or more wireless devices, due to the two-way transmission of data, each device needs to have the ability to send and receive wireless signals.
4, the working principle of wireless bridge
The working principle of the wireless bridge is that the bridge uses the air as a medium to transmit signals, which is simply that one end of the bridge converts the signal in the network cable into a wireless electromagnetic wave signal and transmits it to the air in a directional manner. The bridge at the other end does the opposite, picking up radio electromagnetic signals in the air and converting them into wired signals.
The wireless electromagnetic wave signal can be transmitted by air as the transmission medium, which can solve many problems of difficult construction of wired deployment: such as highways, rivers, mountain streams, or road hardening, and wired deployment and construction difficulties.
Wireless bridge networking has obvious advantages, and can achieve point-to-point or point-to-multipoint network connections at distances of up to 50 kilometers, and data transmission speeds of up to 108Mbps. Effectively solve the problem of network connectivity in the interval, as long as the wireless signal coverage area, the client can easily access the network, the fusion system, without any wiring, the wireless terminal can achieve zero configuration access, so it is very easy to carry out network maintenance and expansion.
Bridges are generally used in the following scenarios: wireless data acquisition, monitoring data transmission (outdoor and elevator), outdoor wireless coverage, outdoor remote wireless bridging, private ISP wireless broadband, unmanned monitoring station data return, etc.
5. How to choose the right bridge
Wireless bridge is a wireless monitoring and transmission equipment commonly used in the field of wireless monitoring, although it is a wireless device like wireless AP and Wireless Router, but it does not need to build wifi coverage, but is used to wireless transmission of video data. Like the switch in wired monitoring, the wireless bridge is an important transmission equipment in wireless monitoring, which is widely used in the two major fields of outdoor surveillance video transmission and elevator surveillance video transmission.
There are many kinds of wireless Bridges on the market, so how to choose a bridge that suits your needs? We will answer your questions from the following aspects.
â‘ Transmission distance
Wireless monitoring projects need to transmit the distance is not the same, wireless bridge transmission distance there are many kinds, some transmission 1~3 km, some transmission 3~5 km, some transmission 5~10 km, some transmission more than 20 km, must be determined according to the monitoring of the transmission distance, as far as possible the maximum transmission distance of the bridge is greater than the monitoring transmission distance, Because rain, fog, snow and other weather in the actual application environment will cause the transmission performance of the bridge to decline, the project construction should reserve sufficient performance margin.
â‘¡ Transmission bandwidth
There are many kinds of transmission rates of wireless bridge, such as 150Mbps, 3000Mbps, 450Mbps, 600Mbps, 900Mbps, etc., which rate to choose can be determined according to wireless monitoring requirements. What users actually need to consider is the transmission performance of the bridge over a specific distance, rather than the theoretical bandwidth data. For example, the theoretical transmission bandwidth of the IP-COM AP625 bridge is 433Mbps, and the actual point-to-point transmission bandwidth can reach 200Mbps at a distance of 2 kilometers, with 25 200W cameras without pressure.
â‘¢ Operating frequency
There are two main operating frequencies of wireless Bridges, 2.4G and 5.8G, and the characteristics of the two Bridges are different. In general, 2.4G wireless bridge is the current mainstream frequency band, good compatibility, good diffraction ability, but the anti-interference is relatively poor, especially in the urban area is vulnerable to wireless signal interference transmitted by other WiFi devices. The 5.8G channel is relatively pure, the anti-interference ability is better, the transmission distance is long, but the diffraction ability is poor.
Urban, downtown, long-distance transmission, camera stream is large, 2.4G interference is more, choose 5.8G wireless bridge. Others such as the transmission distance is relatively close, relatively remote, and the same frequency interference is less, etc. 2.4G wireless bridge is used
â‘£ antenna
Antenna is an important part of wireless bridge, used to transmit and receive wireless signals, no antenna, wireless bridge can not achieve communication. There are many types of antennas, including omnidirectional antennas and directional antennas. Omnidirectional antenna is used for short-range coverage and transmission, and directional antenna should be selected for long-distance bridge. The larger the gain of antenna, the better the performance of wireless bridge.
⑤ Power supply mode
The working environment of the wireless bridge usually involves some complex outdoor environments, such as forests, ports, tunnels, reservoirs and other places, so the power supply is a more troublesome problem. Choosing a wireless bridge that supports POE cable power supply can solve this problem well. IP-COM bridge all support PoE injector power supply, power supply distance up to 60 meters.
â‘¥ Protection level
The wireless bridge works outdoors, the environment is changeable, such as rain, rain and snow, high temperature, etc., the first requirement is waterproof, dustproof, heat resistance, and condensation resistance. For a qualified wireless bridge, these "qualities" are a must.
⑦ Pairing method
At present, there are three mainstream bridge pairing methods: key pairing, dip code pairing, automatic pairing. In terms of the simplicity of engineering applications, especially for projects that install dozens or hundreds of network Bridges at a time, automatic pairing is undoubtedly the best choice. IP-COM network bridge supports the automatic pairing of two network Bridges when they are powered on in the factory state, greatly reducing the workload.
6, wireless bridge installation requirements
Wireless bridge is an important transmission equipment in wireless monitoring, which is widely used in outdoor surveillance video transmission and elevator surveillance video transmission. In addition to selecting the right wireless bridge, we also need the bridge equipment to give full play to its performance advantages after installation to assist users in the project. Therefore, for some installation requirements and precautions of wireless bridge, we should pay more attention to avoid various problems in the later stage.
â‘ Installation height
In the process of wireless transmission, obstacles such as trees, buildings and large reinforced buildings will weaken and block wireless signals. In order to improve the wireless transmission performance and prevent signal damage and weak signal, the user should try to ensure that there are no obstacles in the transmission route of the wireless bridge during installation, and meet the transmission conditions that the two ends can see each other.
Both ends can not be simply understood as point-to-point visibility, which means that there can be no obstacles or potential obstacles in the Fresnel zone (radio wave terminology) in which the antenna is propagated. The main RF energy between the antennas is transmitted in this area, so the transmitting antenna must be high enough above the obstacle to maintain a line of sight path between it and the receiving antenna in order for the communication link to work properly.
â‘¡ Angle and signal debugging
Since the quality of the wireless bridge signal is directly related to the bandwidth and stability of the link, it is necessary to further debug the wireless bridge signal after the installation is completed (the signal strength can be adjusted by adjusting the direction of the antenna on both sides, the pitch Angle, etc.). The signal strength can be checked according to the signal status indicator of the bridge device (three lights, three signals are best, two are average, and one is poor) or the software. Detailed installation procedure for outdoor wireless aps
â‘¢ Requirements for lightning rod
When the wireless bridge is installed in the field, if there are no tall buildings or lightning rod protection nearby, lightning protection measures need to be considered, usually using lightning rod, generally installed in the urban area or surrounded by lightning rod protection, can not be set separately.
It can be seen from the characteristics of the lightning rod that the lightning rod is a lightning source, and the lightning rod will discharge in the grounding path when it is hit by lightning. Therefore, the lightning rod and the protected equipment need to be insulated, otherwise the lightning rod will have a lightning effect on other equipment when discharging. Due to the tip discharge characteristics of the lightning rod, it is easier to cause lightning discharge than the general equipment, so if the lightning rod cannot be isolated from the protected equipment, it will increase the probability of lightning strikes of other equipment. Therefore, the lightning rod grounding must be separate from the device grounding and cannot share the same grounding.
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â‘£ Power supply requirements
The normal input voltage of the PoE power module of the bridge ranges from 100V to 240V and the output voltage ranges from 24V to 48V. If the voltage is lower than or higher than this voltage, the normal operation of the device is affected or the PoE power module is damaged. In view of the unstable and high voltage field power supply, it is necessary to design a PoE power supply solution (such as regulated power supply and UPS power supply) that ADAPTS to the working voltage.
Because the bridge is a precision electronic equipment, it has high requirements for power supply, and is vulnerable to the impact and influence of other power supply equipment, so the power supply of the bridge should be separated from other high-power equipment such as pumping units, oil pumps, etc. When taking power at the same location, UPS, regulated power supply or isolation transformer should be installed to filter out the influence and interference on the power supply when the high-power motor is working.
When the PoE module is used to power the bridge through the network cable, the recommended distance is not more than 60 meters. When this distance is exceeded, it is recommended to move the transmission line near the bridge to meet the recommended power supply distance.
⑤ Device grounding requirements
The wireless bridge should be grounded. If the device is not grounded, the device may run abnormally or be damaged. The grounding resistance of the device should be less than 4 ohms, and the grounding cannot be shared with the lightning rod or strong current line. If PoE power is used, the ground cable also needs to be grounded. Users can ground a Class 5 (or higher) shielded network cable with a ground cable and a PoE adapter to effectively prevent static electricity and lightning strikes. The ground cable and ground point should be waterproof using waterproof tape and waterproof cement according to the waterproof requirements to prevent the ground point from being exposed to the air for a long time, which may cause oxidation or rust.
7, wireless bridge erection method
There are four common wireless bridge transmission modes, the distribution is point-to-point, point-to-multipoint, relay, reflection, here the first monitoring combined with pictures for you to briefly introduce the characteristics of these four wireless transmission modes.
â‘ point-to-point transmission
Point-to-point transmission mode is the simplest transmission mode, that is, we often say PTP, to a single device transmission, and then received by a single device, one-to-one transmission and reception is simple and direct. Point-to-point transmission mode of wireless bridge is often used in the case that the transmission distance is long, or the monitoring point is widely distributed, and point-to-multipoint transmission cannot be achieved.
â‘¡ Point-to-multipoint transmission
The point-to-multipoint transmission mode is developed based on the point-to-point transmission mode, which is often represented as a receiving end to multiple transmitting ends, and is often used for the situation where the transmission distance is relatively close, there are more monitoring points and the distribution is dense.
â‘¢ Relay transmission
The relay transmission mode is because the transmitting end and the receiving end can not avoid the barrier blocking the microwave signal, so the transfer equipment is added in the middle, so that the microwave signal is smoothly transmitted to the receiving end through the transfer equipment, this mode is due to increase the transfer equipment and increase the equipment cost investment, so it is generally not used when unnecessary.
â‘£ Reflection transmission
Reflection transmission is microwave transmission with the help of objects outside the transmission device, such as the transmitting end and the receiving end can not be seen, but there is a large building or a mountain with smooth rock walls in the middle, so that you can adjust the Angle of the equipment, through the building or mountain to reflect microwave signals for wireless communication.
The valve industry plays an important role in the development of the national economy as an important part of preparing for manufacturing. As there is still a gap between China's domestic valve manufacturing industry and the international advanced level, many high-parameter, high-temperature, high-pressure, high-pound critical valves have always depended on imports. In order to promote the localization of valves, the State Council issued the "on the acceleration of the rejuvenation. After several opinions of the equipment manufacturing industry, the relevant national departments have successively made a series of major deployments according to the requirements of the country for major equipment localization, and are led by the National Development and Reform Commission. Together with China National Machinery Industry Association and the China General Machinery Industry Association, Deployed and formulated the valve localization program for major equipment in related fields, and coordinated with related departments several times, and now the localization of valves has formed a consensus in the domestic valve industry.