After the mid-19th century, with the invention of the telegraph and telephone, and the discovery of electromagnetic waves, the field of human communication has produced a fundamental change in the realization of the use of metal wires to transmit information, and even through electromagnetic waves to wireless communication, so that the myth of the "smooth ear", "clairvoyance" became a reality. Clairvoyance" in mythology became a reality. From then on, human information transfer can be detached from the conventional visual and auditory methods, with the use of electrical signals as a new carrier, with this brought a series of iron technology innovation, the beginning of a new era of human communication.
In 1837, the American Samuel Morales (Samuel Morales), who was a member of the American Academy of Arts and Sciences (AASA), developed a new technology called the "electric signal. Morse (Samuel Morse) successfully developed the world's first electromagnetic telegraph. He used his own design of the code, can be converted into a string of information or long or short electrical impulses to the destination, and then converted to the original information. 1844 May 24, Morse in the Capitol, the Federal Supreme Court Chamber of the "Morse code" sent the first telegram in the history of mankind, thus realizing the long-distance Telegraph communication.
In 1864, the British physicist Maxwell (J.c. Maxwel) established a set of electromagnetic theories, predicted the existence of electromagnetic waves, explaining that electromagnetic waves and light have the same nature, both are propagated at the speed of light.
In 1875, a young Scottish man, Alexander. A.G. Bell invented the world's first telephone. A.G. Bell patented the invention in 1876, and the first long-distance telephone experiment between Boston and New York, 300 kilometers apart, was successful in 1878, leading to the establishment of the famous Bell Telephone Company.
In 1888, the young German physicist Heinrich Hertz (H.R. Hertz), who had been a member of the German Academy of Physics for many years, developed a new technology called "the telephone. Hertz (H.R. Hertz) conducted a series of experiments with the electric wave ring, discovered the existence of electromagnetic waves, he used the experiment to prove Maxwell's electromagnetic theory. This experiment stirred the entire scientific community, becoming an important milestone in the history of modern science and technology, leading to the birth of radio and the development of electronic technology.
The discovery of electromagnetic waves had a huge impact. In less than 6 years, Russia's Popov, Italy's Marconi invented the wireless telegraph, the realization of the radio dissemination of information, other radio technology also sprung up. 1904 British electrical engineer Fleming invented the diode. 1906 U.S. physicist Fessenden successfully researched the radio broadcasting. 1907 U.S. physicist DeForest invented the vacuum triode, U.S. electrical engineers. In 1907, American physicist DeForest invented the vacuum transistor, and American electrical engineer Armstrong invented the super-aberrant receiver by applying electronic devices. 1920 American radio expert Conrad established the world's first commercial radio station in Pittsburgh, and since then the broadcasting business has flourished all over the world, and the radio has become a convenient way for people to learn about the current news. 1924, the first short-wave communication line was established between Nauen and Buenos Aires, and the first short-wave communication line between Nauen and Buenos Aires was set up. Buenos Aires between the establishment of the first short-wave communication line in 1924 in Nauen and Buenos Aires, in 1933, the French Clavell established between the United Kingdom and France and the first commercial microwave radio lines, promoting the further development of radio technology.
The discovery of electromagnetic waves also led to the rapid development of image dissemination technology. 1922, 16-year-old American high school student Philo Farnsworth designed the first image dissemination technology. Farnsworth designed the first television facsimile schematic, applied for a patent for the invention in 1929, was ruled to be the first person to invent the television set. 1928 Westinghouse Zwolgin invented the photoelectric picture tube, and with the cooperation of the engineering Van Wass, to achieve the electronic scanning method of television sending and transmission. 1935 United States, the United States of America, New York, the Empire State Building to set up a television station, the following year successfully In 1938, Zwolgin made the first TV camera that meets the practical requirements. After people continue to explore and improve, in 1945 in the three-color principle of operation on the basis of the United States Radio Corporation made the world's first all-tube color television. Until 1946, the American Ross. Weimar invented a high-sensitivity camera tube, the same year the Japanese Professor Hachimoto solved the problem of home television reception antenna, from which a number of countries have established ultra-short-wave relay stations, television rapidly spread.
Image fax is also an important communication. Since 1925, the United States Radio Corporation developed the first practical facsimile machine, facsimile technology continues to innovate. 1972, the technology is mainly used in the news, publishing, meteorology and broadcasting industry; 1972 to 1980, facsimile technology has been completed from the analog to digital, from the mechanical scanning to the electronic scanning, from the low-speed to high-speed transformation, in addition to replacing the telegraph and for the transmission of meteorological maps, Press releases, photographs, satellite cloud charts, but also in the medical, library management, intelligence consulting, financial data, e-postal and other aspects of the application; after 1980, fax technology to the transition to integrated processing terminal equipment, in addition to undertake communication tasks, it also has the ability to image processing and data processing, to become a comprehensive processing terminal. Electrostatic copiers, magnetic tape recorders, radar, lasers and so on are important inventions in the history of information technology.