What is Digital TV?

Digital television is also called digital television or digital television. The so-called digital television is to sample, quantify, and then convert the traditional analog television signals into digital television signals represented by binary numbers, and then perform digital processing and transmission of various functions. , Storage and recording, can also be processed, stored and controlled by electronic computers. The use of digital technology not only enables various television equipment to obtain higher performance than the original analog equipment, but also has new functions that cannot be achieved by analog technology, making television technology enter a new era. ^[1]

Digital TV refers to a new TV system that uses digital TV signals or processes and modulates digital TV signals in all links from the studio to transmission, transmission, and reception. All signal transmission in this system is transmitted through a digital stream composed of 0 and 1 digital strings. The transmission rate of digital signals is 19.39Mb / s. The transmission of such a large data stream ensures the high definition of digital television. , Overcome the inherent disadvantages of analog TV. ^[2]

Digital technology is one of the fastest growing technologies in the past 20 years. Generally speaking, the development of the application of digital technology on television is divided into three main stages: ^[3]

From the difference between digital television and analog television, digital television has the following three characteristics: ^[4]

1. According to the signal transmission method, it can be divided into: terrestrial wireless transmission digital television (terrestrial digital television); satellite transmission digital television (satellite digital television); cable transmission digital television (cable digital television). ^[2]

The steps for digitizing an analog television signal are sampling, quantization, and encoding. ^[6]

For a digital TV cable TV network, according to the sequential transmission direction of its digital TV signal stream, it can be divided into three parts: the front-end broadcast room, the mid-end transmission network media, and the end-set-top box users. ^[7]

1.Broadcast and TV programs transmitting digital signals

This is the basic business of digital TV. Different from the past analog TV broadcasting, due to the use of digital compression technology, digital TV can transmit 6-8 times or more of the original TV channels. Therefore, in addition to the original analog broadcasting, In addition to digital broadcasting of TV channels, digital TV has also added a large number of professional paid channels, such as fishing channels, pregnant women's guides, online exams, and beautiful makeup channels. TV programs transmitted by digital TV can support both standard definition formats and high definition formats. ^[8]

1. Sound image:

The TV signal transmitted by analog is susceptible to interference during transmission, the noise will continue to be superimposed, and the image quality is only quite super

The role and significance of the development of cable digital television has exceeded its own scope, it will have a huge impact on the entire society and economy, promote the development of a series of industries, and then have a more profound impact on the entire society. Specifically, the significance of digital cable TV is mainly reflected in the following aspects: ^[9]

1.High-definition digital TV technology

One of the main directions of the current development of digital television technology is high-definition television. High-definition television has high definition, and at the same time, the technical requirements are more stringent and demanding. He has high requirements for the quality of digital signals, reception and transmission technology. The so-called high-definition digital TV is understood from the literal meaning, emphasizing the clarity of the picture and sound, while increasing the resolution from 720 × 576 to 1920 × 1080. People are increasingly demanding the clarity of TV programs, and high-definition words can be seen in TV stores and various video websites. The development prospect of high-definition digital television is very broad. He is a key part of the development trend of digital television technology. ^[10]

2.Internet TV

The Internet has become an indispensable part of modern life, work and entertainment. People search and get more information on the Internet. Network TV is based on the Internet and brings information to the audience. Compared with ordinary TV, Internet TV has richer program content. At the same time, the terminal equipment of Internet TV is a set-top box or a PC. Through these devices, network interaction can be realized. Compared with one-way TV programs, people are more Willing to order your favorite shows at will. This kind of super-interactivity has caused the Internet TV to have a huge impact on traditional TV. In addition, due to the rapid development of network technology, the quality of Internet TV programs is also increasing, and its clarity can meet user requirements, which also makes More users tend to choose Internet TV. Therefore, with the development of network technology and digital television technology. The development trend of its network TV will become more and more obvious. ^[10]

3. Live satellite TV technology

Different from the former two, the satellite live TV technology relays signals of new digital TV programs through satellites. The development of science and technology has promoted satellite technology, and the function of the repeater of communication satellite has been very powerful. The power of the satellite repeater is very large, it can completely realize the transmission of digital television signals from the sender to the receiver. Compared with the above two digital TV technologies, the outstanding feature of satellite live TV technology is that its coverage is very wide, and the transmission of digital signals worldwide can be achieved by satellite TV technology. Not only that, its equipment is also very simple, and users can watch high-quality digital TV programs through antennas. ^[10]

4. Terrestrial wireless digital TV

The common transmission modes for terrestrial wireless digital are: digital MMDS transmission mode, MUDS transmission mode and "mobile TV" mode. Which mode is used depends on the specific analysis of local TV stations. Three transmission modes are suitable for different situations. For example, in a large area, where the residence is not concentrated and the economy is less developed, you should choose: digital MMDS transmission mode, MUDS transmission mode, although "mobile TV" mode can achieve good results, but its cost is high, one-time investment Larger; in areas with high living density and better economic conditions, the use of "mobile TV" is more advantageous. The signal transmission of the terrestrial digital wireless television is transmitted through electromagnetic waves, which saves a lot of links in the middle and reduces the complexity of the equipment. This is different from the cable digital television and satellite television mentioned earlier. In addition, the cost of wireless digital TV is low, because its service range is small, this feature makes the ground wireless digital equipment simple and low construction cost, which has formed its unique advantages. At the same time, the management of terrestrial wireless television is simple, which can realize unmanned monitoring, saving labor costs. The most important thing is that the terrestrial wireless TV technology has a small service range and its distinctive local characteristics. Different regions can broadcast TV programs that conform to local culture according to local conditions, and are more flexible in program production. Therefore, terrestrial wireless digital television also has good development prospects. ^[10]