What are the advantages and disadvantages of wired transmission media and wireless transmission medi

1. Wired medium: twisted pair, coaxial cable.

and optical fibers. Wireless transmission medium: microwave, infrared.

Lasers or satellites. 2. The cable medium twisted pair is low and the transmission speed is low; Compared with anti-interference and **, coaxial cable is between twisted pair and optical fiber; Optical fibers have the advantages of low optical signal attenuation, high bandwidth and strong anti-interference ability. The wireless transmission medium is electromagnetic waves that are transmitted through the atmosphere.

3. The maintenance of the wired communication link needs to be checked along the line, and when the fault occurs, it is generally difficult to find out the fault point in time, and the wireless data transmission mode only needs to maintain the data transmission module, and the cause can be quickly found out when the fault occurs, and the normal operation of the line can be restored.

The cable is stable and fast. High security, wired, cabling cost is higher than wireless. The wireless speed should be slower, sometimes the distance or the information such as the partition wall is unstable, and it is easy to be interfered with other interference, but it is convenient to be wireless. Poor security. No cabling costs.

Wired transmission. Advantages, stable and fast. Disadvantages, construction troublesome, relatively safer than wireless.

Wireless transmission. Advantages, convenience, disadvantages, data is not secure, unstable, and the relative wired speed is slower. The above is just a brief introduction.

Wired, not limited by distance, weather and other external factors are small, wiring is inconvenient. Wireless transmission, the range of general equipment is small, and the influence of external factors is large, which is trouble-free.

In the computer network, wireless transmission can break through the limitations of the wired network, use space electromagnetic waves to achieve communication between sites, and can provide mobile communication for the majority of users. The most commonly used wireless transmission media are: radio waves, microwaves, and infrared.

Electromagnetic waves can be used in free space to send and receive signals for communication, which is wireless transmission. The Earth's atmosphere provides the physical channel for most of the wireless transmission, which is often referred to as the wireless transmission medium. Wireless transmissions use a wide range of frequency bands, and several bands have been used for communication.

Ultraviolet light and higher wavelengths cannot yet be used for communication.

There are three types of wireless transmission media:

1. Radio waves

Radio waves refer to electromagnetic waves in the radio frequency band that propagate in free space, including air and vacuum.

Radio technology is the technology that transmits sound or other signals through radio waves.

The principle of radio technology is that a change in the intensity of the current in a conductor produces radio waves. Using this phenomenon, information can be loaded on top of radio waves by modulation. When an electric wave travels through space to the receiving end, the electromagnetic field caused by the radio wave.

The change, in turn, creates an electric current in the conductor. The purpose of information transmission is achieved by extracting the information from the current change through demodulation.

2. Microwave

Microwave refers to electromagnetic waves with a frequency of 300MHz-300GHz, which is the abbreviation of a finite frequency band in radio waves, that is, electromagnetic waves with a wavelength between 1 meter (excluding 1 meter) and 1 millimeter, which are decimeter waves, centimeter waves, and millimeter waves.

Collectively referred to as . The frequency of microwaves is higher than that of ordinary radio waves, and it is also commonly referred to as "ultra-high frequency electromagnetic waves".

3. Infrared

Infrared is one of the many invisible rays of the sun's rays, discovered by the German scientist Hoxel in 1800, also known as infrared thermal radiation.

He used the sun's rays with a prism.

Disassembled, thermometers were placed in various different color ribbon positions.

Attempts to measure the heating effect of light of various colors. It turned out that the thermometer on the outside of the red light warmed up the fastest.

Therefore, it is concluded that in the solar spectrum, there must be invisible light on the outside of the red light, which is infrared light. It can also be used as a medium for transmission. The wavelength of infrared rays on the solar spectrum is greater than that of visible light, and the wavelength is.

Infrared can be divided into three parts, namely near-infrared, with wavelengths between; mid-infrared, wavelengths between; Far infrared.

The wavelengths are between.

1.Twisted pair.

One of the oldest but by far the most commonly used transmission medium is the twisted pair (TP), which consists of two copper wires (usually about 1mm in diameter) that are insulated from each other. The two copper wires are twisted together in a spiral so that the interference waves generated by the different wires cancel each other out, significantly reducing the emissions of the wires. Noise cancels out because the noise interferes with both wires in the same way.

Twisted pair cables can reach a bandwidth of several Mbps.

2.Coaxial cable.

Coaxial cable consists of a copper core and a layer of insulation on the outer bread, which is a densely woven mesh cylindrical conductor and covered with a protective plastic jacket.

3.Power line.

Power lines send electrical energy to homes and can also be used for data communication. I won't go into detail here.

4.Optical fiber. Optical fiber is mainly used for long-distance transmission and high-speed LAN of the network backbone.

1. The wired transmission medium mainly includes twisted pair, coaxial cable and optical fiber.

2. Wireless transmission medium is divided into radio wave, microwave, infrared, laser, etc.

Commonly used transmission media are divided into two categories: wired transmission media and wireless transmission media. Different transmission media have different characteristics, and their different characteristics have a great impact on the quality and speed of data communication in the network.

It is divided into wired transmission medium and wireless transmission pure plum medium.

1. Wired transmission medium:

1. Twisted pair.

Advantages and disadvantages: low cost, high density, space saving, easy installation, high speed, general anti-interference, short connection distance.

2. Coaxial cable.

Advantages and disadvantages: good anti-interference, complex access.

3. Optical fiber. Advantages and disadvantages: large communication capacity, small transmission loss, good anti-interference, good confidentiality, small size and light weight, need special equipment connection.

2. Non-wireless transmission medium:

1. Short-wave communication.

Advantages and disadvantages: The communication quality is worse than that of Wang, and the rate is low.

2. Microwave communication is divided into ground microwave relay communication and satellite communication.

Ground microwave relay communication.

Advantages and disadvantages: large channel capacity, high transmission quality, low investment, direct sight between adjacent sites, susceptible to weather influence, poor confidentiality.

Satellite communications. Advantages and disadvantages: long communication distance, large communication capacity, and large propagation delay of 270ms.

1. Wired transmission.

Advantages: Generally less interference, reliability, and strong confidentiality.

Disadvantages: large construction costs. The maintenance of the wired communication link needs to be checked along the way, and it is often difficult to find the point of failure when it occurs. After the user sets up the Tongyin Boxin network, due to the needs of the system, new equipment is usually added, and the use of wired transmission may need to be rewired.

2. Wireless transmission.

Advantages: 1. Low comprehensive cost and more stable performance. It only requires a one-time investment, no need to dig trenches and bury pipes, especially suitable for outdoor distances and occasions that have been renovated. In many cases, users are often limited by geography and the content of their work.

For example, special geographical environments such as mountains, ports and open areas bring great inconvenience to the wiring engineering of wired networks and wired transmission, and the construction period of using wired will be very long, or even impossible to achieve at all.

At this time, the use of wireless monitoring can get rid of the shackles of cables, and has the advantages of short installation cycle, convenient maintenance, strong expansion ability, and rapid recovery of costs.

2. Flexible networking, good scalability, plug and play. Managers can quickly add new wireless monitoring points to the existing network, without laying a network or adding equipment for the new transmission of the wheel, and easily realize remote wireless monitoring.

3. Low maintenance cost. Wireless monitoring and maintenance is maintained by the network provider, and the front-end equipment is a plug-and-play, maintenance-free system.

4. The wireless monitoring system is a combination of monitoring and wireless transmission technology, which can transmit the on-site information of different locations to the wireless monitoring center in real time through wireless communication means, and automatically form a first-class database for future retrieval.

At the wireless monitoring point, the camera is usually used to collect the scene situation in real time, and the camera is connected by a wireless transmission device, and the data signal is sent to the monitoring center by radio waves.

Disadvantages: due to the use of microwave transmission, the frequency band is above 1GHz, the transmission environment is an open space, if used in large cities, radio waves are more complex, relatively easy to external electromagnetic interference.

The microwave signal is transmitted in a straight line, and there can be no mountains and buildings in the middle; If there is an obstacle, it needs to be solved by adding a relay, and the KU band is more seriously affected by the weather, especially in rainy and snowy weather, there will be a more serious rain decay phenomenon.