The most comprehensive wireless bridge knowledge in history, just save this article!

Many friends asked about the knowledge related to wireless bridges. Today I have compiled an article about wireless bridge knowledge for everyone. The content comes from the Internet. The editor has sorted and edited it. I hope it will be helpful to everyone.

Wireless bridge knowledge guide:

• What is a wireless network?
• What is a wireless bridge?
• What does wireless bridge 2.4G and 5.8G mean?
• How wireless bridges work;
• How to choose a wireless bridge;
• Installation requirements for wireless bridges;
• How to set up a wireless bridge.

1. What wireless network?

Wireless network, as the name implies, is a way to build a network without relying on network cables. It is mainly achieved by using wireless communication technology. There are two main ways: wireless network achieved through mobile communication network (such as 4G, 3G or GPRS) and wireless local area network (WiFi).

2. What is a wireless bridge?

As the name implies, a wireless bridge is a wireless network bridge. It uses wireless transmission to build a communication bridge between two or more networks. In addition to the basic features of a wired bridge, a wireless bridge works in the 2.4G or 5.8G frequency band that is exempt from the application of a wireless license, making it easier to deploy than other wired network devices.

To understand a wireless bridge from 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, and 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 in the 5.8GHz frequency band.

[[232596]]

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. In short, the propagation performance is good, and it is not a big deal if the propagation path is slightly blocked. In addition, 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 the signals emitted by other devices, resulting in a decrease in transmission quality. In addition, 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 channels, and large transmission bandwidth. The transmission bandwidth starts at 433Mbps and can easily reach more than 1Gbps. It is suitable for use in scenarios with high data transmission requirements.

The disadvantages are high frequency, short signal wavelength, poor penetration, and no obstruction during transmission. The cost of 5.8G equipment is higher than 2.4G and 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 must have the ability to send and receive wireless signals.

4. Working principle of wireless bridge

The working principle of a wireless bridge is that the bridge uses the air as a medium to transmit signals. In simple terms, the bridge at one end converts the signal in the network cable into a radio electromagnetic wave signal and transmits it directionally into the air. The bridge at the other end does the opposite, it receives the radio electromagnetic wave signal in the air and converts it into a wired signal.

Wireless electromagnetic wave signals can be transmitted using air as the transmission medium, which can solve many problems that make wired deployment construction difficult: for example, obstacles such as highways, rivers, and mountain streams, or hardened roads, which make wired deployment construction difficult.

Wireless bridge networking has obvious advantages. It can achieve point-to-point or point-to-multipoint network connection at a distance of up to 50 kilometers, with a data transmission speed of up to 108Mbps. It effectively solves the problem of network connectivity in the interval. As long as it is within the wireless signal coverage area, the client can easily access the network and integrate the system without 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, unmanned monitoring station data backhaul, etc.

5. How to choose a suitable bridge

A wireless bridge is a wireless monitoring transmission device commonly used in the field of wireless monitoring. Although it is a wireless device like a wireless AP and a wireless router, it is not used to build WiFi coverage, but to transmit video data wirelessly. Like switches in wired monitoring, wireless bridges are important transmission devices in wireless monitoring and are widely used in the two fields of outdoor monitoring video transmission and elevator monitoring video transmission.

There are numerous types of wireless bridges on the market. How do you choose a bridge that suits your needs? We will answer your questions from the following aspects.

①Transmission distance

The transmission distances required for wireless monitoring projects are not the same. There are also many types of transmission distances for wireless bridges, some of which are 1 to 3 kilometers, some are 3 to 5 kilometers, some are 5 to 10 kilometers, and some are more than 20 kilometers. It must be determined based on the transmission distance of the monitoring. The maximum transmission distance of the bridge should be greater than the monitoring transmission distance as much as possible, because rain, fog, snow and other weather conditions in the actual application environment will cause the transmission performance of the bridge to decline, and sufficient performance margin should be reserved for engineering construction.

②Transmission bandwidth

There are many transmission rates for wireless bridges, such as 150Mbps, 3000Mbps, 450Mbps, 600Mbps, 900Mbps, etc. The rate can be selected according to the wireless monitoring requirements. 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 point-to-point transmission bandwidth can be measured to be 200Mbps, which can easily carry 25 200W cameras.

③ Operating frequency

There are two mainstream working frequencies of wireless bridges, 2.4G and 5.8G, and the characteristics of the two bridges are different. Generally speaking, 2.4G wireless bridges are the current mainstream frequency band, with good compatibility and diffraction ability, but poor anti-interference ability, especially in urban areas, which are easily interfered by wireless signals emitted by other WiFi devices. 5.8G channels are relatively pure, with better anti-interference ability and long transmission distance, but poor diffraction ability.

In urban areas, busy streets, long-distance transmission, large camera bit streams, and 2.4G interference, choose a 5.8G wireless bridge. For other situations such as short transmission distances, remote areas, and less co-frequency interference, use a 2.4G wireless bridge.

④Antenna

Antennas are important components of wireless bridges, used to transmit and receive wireless signals. Without antennas, wireless bridges cannot communicate. There are many types of antennas, including omnidirectional antennas and directional antennas. Omnidirectional antennas are used for short-distance coverage and transmission, while directional antennas should be used for long-distance bridging. The greater the antenna gain, the better the performance of the wireless bridge.

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 a more troublesome problem. Choosing a wireless bridge that supports POE network cable power supply can solve this problem 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 a changeable environment, such as rain, snow, high temperature, etc. The primary requirements are waterproof, dustproof, heat-resistant, and condensation-resistant. These "qualities" are necessary for a qualified wireless bridge.

⑦Pairing method

At present, there are three mainstream pairing methods for bridges: key pairing, dial pairing, and automatic pairing. In terms of the simplicity of engineering application, especially for projects that install dozens or hundreds of bridges at one time, automatic pairing is undoubtedly the best choice. IP-COM bridges support automatic pairing when two bridges are powered on in the factory state, which greatly reduces the workload.

6. Wireless bridge installation requirements

Wireless bridges are important transmission equipment in wireless monitoring and are widely used in the two fields of outdoor monitoring video transmission and elevator monitoring 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 the project. Therefore, we should pay more attention to some installation requirements and precautions of wireless bridges to avoid various problems later.

①Installation height

When wireless bridges are transmitting wirelessly, obstacles such as trees, buildings, and large reinforced concrete structures will weaken and block wireless signals. To improve wireless transmission performance and prevent signal damage and weak signals, users should try to ensure that there are no obstacles blocking the transmission route of the wireless bridge during installation, so that both ends can see each other.

Visibility at both ends cannot be simply understood as point-to-point visibility. It means that there should be no obstacles or potential obstacles in the Fresnel zone (a radio wave term) where the antenna propagates. The main RF energy between antennas is transmitted in this area, so the transmitting antenna must be high enough above the obstacles to maintain a line of sight between it and the receiving antenna to ensure the normal operation of the communication link.

②Angle 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 further debugged after installation (the signal strength can be adjusted by adjusting the direction of the antennas on both sides, the pitch angle, etc.). You can check the signal strength status according to the signal status indicator of the bridge device (three lights, three signals are excellent, two are general, and one is poor) or the software. Detailed installation steps for outdoor wireless AP

③Lightning rod requirements

When the wireless bridge is installed outdoors, if there are no tall buildings or lightning rods nearby, lightning protection measures need to be considered. Usually, lightning rods are used. Generally, when it is installed in urban areas or there are lightning rods around it, a separate lightning rod does not need to be installed.

From the characteristics of lightning rods, it can be seen that lightning rods attract lightning. When struck by lightning, lightning rods will discharge on the grounding 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. Since lightning rods are more likely to cause lightning discharge than general equipment due to their high-performance discharge characteristics, if the lightning rod cannot be insulated and isolated from the protected equipment, the probability of lightning strikes on other equipment will increase. Therefore, the lightning rod grounding needs to be separated from the equipment grounding and cannot share the same grounding.

④Power supply requirements

The normal input voltage of the PoE power supply module of the bridge is 100V~240V and the output voltage is 24V-48V. Voltages lower or higher than this will affect the normal operation of the equipment or cause abnormal damage to the PoE power supply module. In view of unstable and high voltage in the field, it is necessary to design a PoE power supply solution that adapts to the working voltage (such as a voltage stabilizer, UPS power supply).

Since the network bridge is a precision electronic device with high power requirements and is easily impacted and affected by other power supply equipment, the power supply of the network bridge should be separated from other high-power equipment such as oil pumps and oil pumps. When power is taken from the same location, UPS, voltage stabilizer or isolation transformer should be installed to filter out the impact and interference of high-power motors on the power supply during operation.

When using a PoE module to power a bridge through a network cable, the recommended distance is no more than 60 meters. If the distance exceeds this, it is recommended to move the power transmission line closer to the bridge to meet the recommended power supply distance requirements.

⑤ Equipment grounding requirements

Wireless bridges should be grounded for use. Failure to ground the equipment will cause problems such as abnormal operation and damage. The equipment grounding resistance should be less than 4 ohms, and it cannot be grounded together with lightning rods, strong power lines, etc. If a PoE power ground wire is used, it also needs to be grounded. Users can combine Category 5e (or above) shielded network cables with ground wires with PoE adapters for grounding to conveniently and effectively prevent static electricity and lightning hazards. The grounding wire and grounding point should be waterproofed with waterproof tape and waterproof putty in accordance with waterproof requirements to prevent the grounding wire and grounding point from being exposed to the air for a long time, which may cause oxidation, rust, and other problems that affect the grounding effect.

7. How to set up a wireless bridge

There are four common wireless bridge transmission modes, namely point-to-point, point-to-multipoint, relay, and reflection. Here, ***Monitor combines pictures to briefly introduce 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 transmission and reception are simple and direct. 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, and point-to-multipoint transmission is not possible.

②Point-to-multipoint transmission

The point-to-multipoint transmission mode is developed based on the point-to-point transmission mode. It is often manifested as one receiving end to multiple transmitting ends. It is often used in situations where the transmission distance is short, there are many monitoring points, and the distribution is dense.

③Relay transmission

The relay transmission mode is due to the fact that there are unavoidable obstacles blocking the microwave signal between the transmitting end and the receiving end, so a transit device is added in the middle to allow the microwave signal to be smoothly transmitted to the receiving end through the transit device. This mode requires adding transit equipment and increases equipment cost investment, so it is generally not used when it is not necessary.

④Reflection transmission

Reflection transmission is the use of objects other than the transmission equipment to transmit microwaves. For example, the transmitting and receiving ends cannot have line of sight, but there happens to be a large building or a mountain with smooth rock walls in the middle. In this way, wireless communication can be achieved by adjusting the angle of the equipment and reflecting the microwave signal through the building or mountain.