This article will give you a comprehensive understanding of wireless bridge knowledge, such as do you know the difference between 2.4G and 5.8G?
Introduction to wireless bridge knowledge:
1. What is a wireless network
2. What is a wireless bridge
3. Wireless The meaning of 2.4G and 5.8G bridges
4. How wireless bridges work
5. How to choose wireless bridges
6. Wireless bridges Installation requirements
7. How to set up a wireless bridge
1. What is a wireless network?
Wireless network, as the name suggests, can be carried out without relying on network cables. The way the network is established is mainly achieved by using wireless communication technology. There are two main methods: wireless network (such as 4G, 3G or GPRS) and wireless local area network (WiFi) implemented through mobile communication networks.
2. What is a wireless bridge?
As the name suggests, a wireless bridge is a bridge of wireless networks. It uses wireless transmission to build a communication bridge between two or more networks. . In addition to having the basic characteristics of wired bridges, wireless bridges operate in the 2.4G or 5.8G wireless license-free frequency bands, making them more convenient to deploy than other wired network equipment.
Understanding the wireless bridge in terms of its function, 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 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 frequency band and 802.11a and 802.11n wireless bridges in the 5.8GHz frequency band.
3. The meaning of wireless bridge 2.4G and 5.8G
2.4G bridge:
The advantages are low frequency, long wavelength and strong diffraction ability . To put it simply, the propagation performance is good, and it doesn’t matter if the propagation path is slightly blocked. Furthermore, the cost is relatively low.
The disadvantage is that there are many devices using the 2.4G frequency band, and the electromagnetic wave signals emitted by the bridge are easily interfered by signals emitted by other devices, resulting in a decrease in transmission quality. Furthermore, it is limited by the transmission bandwidth of the 2.4GHz frequency 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. Suitable for scenarios with high data transmission requirements.
The disadvantages are high frequency, short signal wavelength, poor penetration, and no obstruction during propagation. The cost of 5.8G equipment is higher than that of 2.4G, and it is still in the popularization stage.
A wireless bridge transmission system usually consists 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. Working principle of wireless bridge
The working principle of wireless bridge is actually that the bridge uses air as the medium to propagate signals. Simply put, one end of the bridge connects the network cable to The signal in the radio is converted into a radio electromagnetic wave signal and directed into the air. The bridge at the other end does the opposite. It receives radio electromagnetic wave signals in the air and converts them into wired signals.
Radio electromagnetic wave signals can propagate using air as the transmission medium, which can solve many difficult problems in wired deployment and construction: such as highways, rivers, and mountain streams being blocked, or road hardening, making wired deployment and construction difficult, etc.
Wireless bridge networking has obvious advantages. It can realize point-to-point or point-to-multipoint network connections over a distance of up to 50 kilometers, with data transmission speeds up to 108Mbps. Effectively solves the problem of inter-area network connectivity. As long as the client is within the wireless signal coverage area, the client can easily access the network. The integrated system does not require any wiring. The wireless terminal can achieve zero-configuration access, so it is very easy to maintain and expand the network. .
Network bridges are generally used in the following scenarios: wireless data collection, monitoring data transmission (outdoors and elevators), outdoor wireless coverage, outdoor long-distance wireless bridging, private ISP wireless broadband, and unattended monitoring stations Data return, etc.
5. How to choose a suitable network bridge
A wireless bridge is a wireless monitoring transmission device commonly used in the field of wireless monitoring. Although it is also wireless like a wireless AP and a wireless router. device, but it is not used to build wifi coverage, but is used to wirelessly transmit video data. Like switches in wired surveillance, wireless bridges are important transmission equipment in wireless surveillance and are widely used in the two fields of outdoor surveillance video transmission and elevator surveillance video transmission.
There are countless types of wireless bridges on the market. How to choose a bridge that suits your needs? We will answer your questions from the following aspects.
①Transmission distance
Wireless monitoring projects require different transmission distances. There are also many types of transmission distances for wireless bridges. Some transmit 1 to 3 kilometers, and some transmit 3~5 kilometers, some transmit 5~10 kilometers, and some transmit more than 20 kilometers. It must be determined according to the transmission distance of the monitoring. As far as possible, the maximum transmission distance of the network bridge is greater than the monitoring transmission distance, because rain, Weather such as fog and snow will cause the transmission performance of the network bridge to decrease, and sufficient performance margin should be reserved for project construction.
②Transmission bandwidth
There are many transmission rates for wireless bridges, such as 150Mbps, 3000Mbps, 450Mbps, 600Mbps, 900Mbps, etc. Which rate to choose can be based on the wireless monitoring requirements Come and decide. What users actually need to consider is the transmission performance of the bridge at a specific distance, rather than the theoretical bandwidth data. For example, the theoretical transmission bandwidth of the IP-COM AP625 bridge is 433Mbps. At a distance of 2 kilometers, the measured point-to-point transmission bandwidth can reach 200Mbps, and it can carry 25 200W cameras without any pressure.
③Working frequency
There are two mainstream working frequencies of wireless bridges, 2.4G and 5.8G. The characteristics of the two bridges are different. Generally speaking, 2.4G wireless bridges are the current mainstream frequency band, with good compatibility and good diffraction ability, but poor anti-interference performance. Especially when used in urban areas, they are susceptible to interference from wireless signals emitted by other WiFi devices. The 5.8G channel is relatively pure, has better anti-interference ability, has a long transmission distance, but has poor diffraction ability.
In urban areas, busy cities, long-distance transmission, large camera bit streams, and 2.4G interference, choose a 5.8G wireless bridge. For other applications such as those with shorter transmission distances, relatively remote areas, and less co-channel interference, use 2.4G wireless bridges
④Antenna
The antenna is an important accessory of the wireless bridge. To transmit and receive wireless signals, without an antenna, a wireless bridge cannot communicate. There are many types of antennas, including omnidirectional antennas and directional antennas. Omnidirectional antennas are used for short-range coverage and transmission. Directional antennas should be selected for long-distance bridging. The greater the antenna gain, the better the wireless bridge performance.
⑤Power supply method
The working environment of wireless bridges usually involves some complex outdoor environments, such as forests, ports, tunnels, reservoirs, etc., so power supply is more troublesome. question. Choosing a wireless bridge that supports POE network cable power supply can solve this problem very well. All IP-COM bridges support PoE injector power supply, and the power supply distance can reach 60 meters.
⑥Protection level
Wireless bridges mostly work outdoors in changeable environments, such as rain, snow, high temperatures, etc. The primary requirements are waterproof, dustproof, heat-resistant, and anti-condensation. . For a qualified wireless bridge, these "qualities" are necessary.
⑦Pairing method
Currently, there are three mainstream pairing methods for network bridges: button pairing, dial pairing, and automatic pairing. In terms of the simplicity of engineering applications, especially projects where dozens or hundreds of network bridges are installed at one time, automatic pairing is undoubtedly the best choice. The IP-COM bridge supports automatic pairing when the two bridges 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 surveillance and is widely used in the two fields of outdoor surveillance video transmission and elevator surveillance video transmission. . In addition to selecting a suitable wireless bridge, we also need the bridge equipment to give full play to its performance advantages after installation to assist users in completing their projects. Therefore, we must pay more attention to some installation requirements and precautions of wireless bridges to avoid encountering various problems later.
①Installation height
During the wireless transmission process of the wireless bridge, obstacles such as trees, buildings and large steel buildings will weaken and block the wireless signal. In order to improve wireless transmission performance and prevent signal damage and weak signals, users should try their best to ensure that there are no obstacles in the transmission route of the wireless bridge during installation, so that both ends can see each other's transmission conditions.
Visibility at both ends cannot simply be understood as point-to-point visibility. It means that there can be no obstacles or potential obstacles in the Fresnel zone (radio wave terminology) of the antenna propagation. The main radio frequency energy between 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 to ensure that the communication link works properly.
② Angle and signal debugging
Since the quality of the wireless bridge signal is directly related to the bandwidth and stability of the link, the wireless bridge signal must be debugged after the installation is completed. Further debugging (the signal strength can be adjusted by adjusting the direction and pitch angle of the antennas on both sides). You can check the signal strength status according to the signal status indicator lights of the bridge device (three lights, three have the best signal, two have average, and one has poor signal) or the software.
Detailed installation steps of outdoor wireless AP
③Lightning rod requirements
When installing the wireless bridge in the wild, if there are no tall buildings or lightning rod protection nearby, lightning protection measures need to be considered. Lightning rods are usually used. Generally, when installing in urban areas or with lightning rod protection around, it is not necessary to set up separate lightning rods.
It can be seen from the characteristics of lightning rods that lightning rods induce lightning. When lightning rods are struck by lightning, they will discharge on the ground path. Therefore, the lightning rod and the protected equipment need to be insulated and isolated, otherwise the lightning rod will have a lightning strike effect on other equipment when it discharges. Because lightning rods are more likely to cause lightning discharges than ordinary equipment due to their tip discharge characteristics, if the lightning rod cannot be insulated from the protected equipment, it will increase the probability of lightning strikes on other equipment. Therefore, the lightning rod grounding needs to be separated from the equipment grounding, and one grounding cannot be used exclusively.
④Power supply requirements
The normal power supply input voltage of the PoE power supply module of the network bridge is 100V~240V and the output voltage is 24V-48V. Lower or higher voltage will affect the normal operation of the equipment. work or cause abnormal damage to the PoE power supply module. In view of the unstable and high voltage of outdoor power supply, it is necessary to design a PoE power supply solution that adapts to the working voltage (such as regulated power supply, UPS power supply).
Since the network bridge is a precision electronic device with high power supply requirements and is susceptible to the impact and influence of other power supply equipment, the power supply of the network bridge should be consistent with other high-power equipment such as oil pumping units, The oil transfer pumps etc. are powered separately. When taking power at the same location, a UPS, regulated power supply or isolation transformer should be installed to filter out the impact and interference on the power supply when high-power motors are working.
When using a PoE module to power the bridge through a network cable, it is recommended that the distance should not exceed 60 meters. If this distance is exceeded, it is recommended to move the transmission line near the bridge to meet the recommended power supply distance requirements.
⑤Equipment grounding requirements
Wireless bridges should be grounded. Failure to ground the equipment will lead to abnormal operation, damage and other problems. The grounding resistance of the equipment should be less than 4 ohms and cannot be in contact with lightning rods. , strong current lines and other special grounding. If PoE power supply ground wire is used, it also needs to be grounded. Users can use a Category 5e (or above) shielded network cable with a ground wire combined with a PoE adapter for grounding, which can conveniently and effectively prevent static electricity and lightning strike hazards. The grounding wire and grounding point should be made waterproof in accordance with waterproofing requirements using waterproof tape and waterproof cement to prevent the grounding wire and grounding point from being oxidized and rusted due to long-term exposure to the air, which affects the grounding effect.
7. How to set up wireless bridges
There are four common wireless bridge transmission modes, which are point-to-point, point-to-multipoint, relay, and reflection. The first one here is Monitoring combined with pictures briefly introduces the characteristics of these four wireless transmission modes.
①Point-to-point transmission
Point-to-point transmission mode is the simplest transmission mode, which is what we often call PTP. It is transmitted by a single device and then received by a single device, one-to-one. Transmitting and receiving are simple and straightforward. The point-to-point transmission mode of wireless bridges is often used in situations where the transmission distance is long or the monitoring points are widely distributed, making point-to-multipoint transmission impossible.
②Point-to-multipoint transmission
The point-to-multipoint transmission mode is developed based on the point-to-point transmission mode. It often appears as one receiving end to multiple transmitting ends. It is often used The transmission distance is short, there are many monitoring points and the distribution is dense.
③Relay transmission
The relay transmission mode is because there are unavoidable obstacles blocking the microwave signal between the transmitter and the receiver, so a relay device is added in the middle. Allow the microwave signal to be smoothly transmitted to the receiving end through the relay equipment. This mode requires additional relay equipment and increases equipment costs, so it is generally not used when it is unnecessary.
④Reflective transmission
Reflective transmission uses objects other than the transmission equipment for microwave transmission and transmission. For example, the transmitter and the receiver cannot see through each other, but they are right in the middle. If you have a larger building or a mountain with smooth rock walls, you can adjust the angle of the device to reflect microwave signals through the building or mountain for wireless communication.