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List of contents in this article:

• 1、What is the main system of the network transport layer communication system? Some system composition
• 5, What is SDH?
• 6, What is a system that does not belong to frequency band transmission

What is a digital communication system and what are its types?

1. Digital communication is a communication method that uses digital signals as carriers to transmit messages, or uses digital signals to digitally modulate carrier waves before transmitting them., can transmit digital signals such as telegrams and digital data, as well as analog signals such as digitally processed voice and images.

2. Digital communication systems can be further subdivided into digital frequency band transmission communication system, digital baseband transmission communication system, and analog signal digital transmission communication system. The basic feature of digital communication is that its messages or signals have "discrete" or "digital" characteristics, so that digital communication has many special problems.

3. The purpose of the basic model communication of the communication system is to deliver messages. Messages include symbols, text, speech, music, pictures, data, images and other forms. Basic point-to-point communication is to pass messages from the sender to the receiver through a certain channel. The basic model description of the communication system is shown in Figure 1.

4. The data communication between computers as terminals belongs to digital communication because the signal itself is in digital form. Multi-way communication using time division or code division in satellite communication is also a digital communication. Digital communication system: source: convert the original information into the original electrical signal.

Illustration of the line connection of monitor equipment

1. The transmission part is the image signal path of the system. Generally speaking, the transmission part refers to the transmission of image signals. However, because some systems need to transmit sound signals in addition to images.

2. The monitoring network cable connection method is as follows: First, make an 8-core network cable. Arrange the 8-core network cables in the order shown in the figure below, and pay special attention to the corresponding green line of "6" and the white line of "3" in the figure.

3. Generally, the tail wire of the surveillance camera has two connectors, namely the power plug and the video output plug (as shown in the figure below); the round 5mm plug is the DC12V power supply plug, which is directly connected to the power adapter to power the camera; the Q9 head is the video output plug of the camera, which is connected to the video cable. The male head.

4. Generally, the power supply of surveillance cameras is 12V and 24V, and there are also 5V. The following is an example of 12V. The power supply has 7 wiring, which are divided into input and output. Input": The input has three wiring columns, which are L, N and ground wires from left to right in the figure above.

digital band-pass transmission system refers to

1. Baseband transmission system: Baseband transmission system refers to a system that transmits digital signals directly to the channel without modulation.It includes digital baseband transmission system and digital baseband transmission system. Digital modulation system: Digital modulation system refers to a system that converts digital signals into analog signals and then transmits them to the channel.

2. Digital transmission system generally refers to the digital signal transmission system used in computer networks, radio and television and other fields. It is mainly used to transmit digital information from one point to another. Digital transmission systems usually need to consider bandwidth, transmission speed, signal distortion and other issues to ensure the accuracy and integrity of information during transmission.

3. Digital communication is a communication method that uses digital signals as a carrier to transmit messages, or uses digital signals to digitally modulate carriers before transmitting them. It can transmit digital signals such as telegrams and digital data, as well as analog signals such as digitally processed voice and images.

4. Simply put, a digital communication system refers to a communication system that uses digital signals to transmit messages.

What are the main systems of the network transmission layer communication system

Network system, communication system and software system are the three major information transmission systems that constitute the information network.

Internet Service Provider (ISP): ISP is an organization or company that provides access to the Internet. They enable individual users and enterprises to connect to the Internet by establishing network infrastructure and providing network access services.

The communication system is roughly composed of three parts: the transmitter (source and transmitting device), the channel, the receiving device (the receiver and receiving device), and the noise source.

What is SDH?

SDH is a technical system composed of information structures that provide corresponding levels for the transmission of digital signals at different rates, including reuse methods and mapping methods, as well as related synchronization methods.

SDH (Synchronous DigiTal Hierarchy, synchronous digital system) is a comprehensive information transmission network that integrates the functions of complex connection, line transmission and exchange and is operated by a unified network management system. It is a synchronous optical network (SONET) proposed by the Bell Institute of Communication Technology in the United States.

SDH is a synchronous digital system. According to the proposed definition of ITU-T, it is a technical system composed of a corresponding level of information structure for the transmission of digital signals at different speeds, including reuse methods and mapping methods, and related synchronization methods. PDH is a quasi-synchronous digital series.

SDH is Synchronous Digital Hierarchy, a synchronous digital system. According to the recommendation of ITU-T, SDH is defined forThe transmission of digital signals at different rates provides a corresponding level of information structure, including reuse methods and mapping methods, as well as a technical system composed of related synchronization methods.

Synchronized digital system. SDH (Synchronous Digital Hierarchy), according to the proposed definition of ITU-T, provides a corresponding level of information structure for the transmission of digital signals at different rates, including multiple use methods and mapping methods, as well as related synchronization. A technical system composed of methods.

Usually SDH/SONET, known as optical synchronous digital transmission network, is one of the foundations of broadband integrated digital network B-ISDN. It is a quasi-synchronous digital series PDH (Plesio) for follow-on applications.A revolution of chronous Digital Hierarchy). The traditional digital communication system is asynchronous (or quasi-synchronous) digital series (PDH).

What is the system that does not belong to frequency band transmission

Digital satellite transmission system belongs to frequency band transmission. According to the relevant information of the query, both the digital microwave transmission system and the digital satellite transmission system belong to the frequency band transmission. Band transmission is a transmission method in which a signal is moduted and transmitted to the terminal and then demoduted.

Baseband transmission, also known as digital transmission, refers to converting the data to be transmitted into digital signals and transmitting it on the channel with a fixed frequency. For example, the signals in the computer network are transmitted in the baseband.

The use of a frequency band transmission system can make full use of the analog channels of the existing public telephone network for data communication. The frequency band transmission method is to convert the data baseband signal represented by "1 and "0", or the positive and negative pulse, into an AC channel signal that is convenient for transmission on the communication line through the modulator.

Devices with modulation and demodulation functions are called modems, that is, Modems. The frequency band transmission is relatively complex and the transmission distance is relatively long. If the modem is equipped through the city call system, the transmission distance is not limited. The PLC network generally has a limited range, so the PLC network mostly uses baseband transmission.