Telecommunications is an important pillar of the information society. No matter in human social and economic activities, or in all aspects of people's daily life, it is inseparable from telecommunications, an efficient and reliable means.
What is "telecommunications"? The definition of ITU is: "Communication using wired electricity, radio, light or other electromagnetic systems." According to this definition, the sender uses any electromagnetic system, including wired telecommunication system, wireless telecommunication system, optical communication system and other electromagnetic systems, and adopts any forms of expression, including symbols, characters, sounds, images and various visible, audible or usable signals composed of these forms. The process of sending information to one or more recipients is called telecommunications. It includes not only traditional telecommunication media such as telegraph and telephone, but also modern telecommunication media such as optical fiber communication, data communication and satellite communication, including both the above-mentioned two-way information transmission media and unidirectional information transmission media such as radio and television.
The history of transmitting information by electricity began with telegrams. Telegraph is a way of transmitting information by symbols, which is also called digital mode. However, after the invention of telephone by 1876, analog mode has occupied an absolute advantage in the field of telecommunications. In 1950s, the appearance of PCM technology brought a ray of light to digital communication. But its real growth and development, and even the unification of the world, mainly rely on the power of electronic computers. Therefore, some people regard "C&C" (the integration of communication and computer) as an important symbol of a new revolution in the history of human information. Today, when we talk about "telecommunications", we have to talk about the wide application of computers in various telecommunications fields. It not only plays a key role in realizing the intelligence of telecommunications, making telecommunications no longer simply "transmit" information, but also increases the functions of information processing and storage.
Telecommunications started with wired communication with metal wires, and by the end of 19, wireless telegrams appeared, which made wireless communication methods rise for a period of time. However, due to some inherent weaknesses of wireless communication, it was difficult to overcome under the technical conditions at that time, so for a long time, except for navigation and disaster relief, it was generally in a "standby" state. Due to the development of technology, not only the wireless mode has made a comeback, but also a brand-new communication mode with optical fiber as the transmission medium has emerged. This not only brings the diversification of telecommunication transmission modes, but also lays a material foundation for the high-speed and personalization of telecommunications.
As can be seen from the above, although the basic concept of telecommunications 100 has not changed for many years, its extension has experienced vicissitudes. The dominant position of telephone has been shaken, and the arrival of information superhighway and internet has brought unprecedented impact to the concept and mode of traditional telecommunications.