Radio engineering and television
The seventh of May is traditionally named Radio Day. It was on this day in 1895 that A- S. Popov, a Russian scientist, reported in the Physics Department of the Russian Physical and Chemical Society on his invention of a sensitive re ceiver which detected and registered electric oscillations In the atmosphere. He demonstrated his radio-receiving set in operation. Popov's invention found practical application in meteorology and communication. Since then, radio communication and radio engineering have made a tremendous progress. A great number of scientists and inventors contributed to this progress. Radio has become such a part of our life that we cannot imagine our existence without it. Now it is hardly possible to name a sphere of science, engineering or national economy where radio equipment is not used.
Today radio engineering is a very vast field, which includes a great number of specialized branches, such as radio communication, television, radiolocation (radar), radioastron-omy, radiotelemetry, automatics, cybernetics, and so on.
The invention of the radio (electronic) valve made possible the transmission of speech, music and vision signals and thus led to broadcasting and television. While radar helps navigation at sea and makes air navigation and flight safe, television helps man to see what goes on hundreds and thousands of kilometres away. Man is already able to cast his electric eye at the bottom of the sea, inside a roaring blast furnace and a live nuclear reactor. Without radio, radiobeacon and radiocompass it would be not safe to travel by air and by sea in foggy and stormy weather. Without radioelectronic equipment space flight would be impossible. Radiolocators installed on sputniks help see from outer space the formation of typhoons or hurricanes, calculate their force and direction, determine spring floods of rivers, etc.
Radio and television are not only the reliable means of communication but also efficient means of educating people, spreading knowledge and ideas and raising the cultural level of the population. Television finds ever wider application in various fields of national economy.
In radioastronomy radiotelescopes are used to investigate the Universe, to obtain data on chemical composition and surface conditions of the Sun and other planets.
Radio engineering technique is widely used in radiotelemetry to indicate or record a measurable quantity at a distance.
At present we produce equipment for powerful broadcasting and television centres and radio-relay stations, electronic computers, radar stations, telecontrol and telemetric systems, etc.
Radiobroadcasting is the technique of use of radio (electromagnetic) waves for wireless transmitting of sound. Radiowaves are produced at the broadcasting station and radiated by the aerial. Radiowaves generated by the radio transmitter and emitted by the aerial propagate in all directions. Radioreceivers receive, transform and amplify the energy of radiowaves into audio signals so that they can reach the loudspeaker, headphones, a relay, recording equipment, etc. Radioreceiver is one of the main elements of broadcasting, communication systems, television, radar and many other fields of engineering. The lower the power of signals received, the higher sensitivity of the receiver should be.
Broadcasting based on digital coding has revealed many advantages over conventional broadcasting. It consists in converting soundwaves into series of digits and their subsequent transmission in the form of monofrequential pulses. A signal is then received and after amplification is sent to the acoustic system for reproduction. Digital coding enhances the quality of broadcasting, makes it possible to reduce considerably the size of new receiver-decoders. In digital broadcasting more than one station can use one and the same wavelength without interference.
Many fundamentally new radioengineering devices have appeared of late, which infinitely extend the range of their application.
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