Modern communication technology can be said to be developing towards a more direct and effective communication mode. For example, in the past, the way of sending letters by three people was replaced by e-mail, and finally it was replaced by a phone that people in two distant places could talk more directly and quickly; From this point of view, it is easy to predict that the further development of telephone is videophone, which can provide more practical and authentic calls. This evolutionary form is also applicable to the field of broadcasting. Pure auditory broadcasting will inevitably be replaced by TV with visual effects, and with the development of color TV sets, black and white TV sets are gradually scrapped. Similarly, color TV sets will be replaced by high-definition TVs that can provide more realistic and lifelike visual pictures. Our goal is to build a broadband telecommunication system and introduce the basic technology of broadband in detail. Therefore, in figure 1, five key points are given: optical communication technology, synchronous digital transmission system, broadband digital integrated service network and asynchronous transmission mode, high-speed data transmission and broadband video communication service, which are the core parts of broadband telecommunication system. In short, backstage and broadband telecom will check.

The first thing to check is the basic technology of telecommunication network, such as signal transmission, conversion, transmission, encapsulation, integrated service digital network, broadband integrated service digital network and so on. Finally, the key technologies of broadband communication system are discussed, such as optical communication transmission medium, broadband transmission, asynchronous transmission mode, high-speed data network and broadband video technology.

From the example of the evolution of videophone and HDTV, we can draw a conclusion that the future communication technology will be carried out through broadband telecommunications around video signals. This joint service consists of various high-speed and broadband services in the form of video, such as videophone, video conference, video monitoring, cable TV signal distribution and HDTV signal distribution.