Telecommunications, according to PEARS Encyclopedia, is generally applied to the sending of messages by telegraph, telephone, radio, television or radar. The first submarines telegraph cable between England and France was laid in 1850. Following Hertz’s investigations into electric waves, Marconi’s invention led to Britain being linked with Europe by wireless telegraphy in 1899. The electro- magnetic telephone was invented by Alexander Graham Bell in 1876.
Now satellite communication has become common. It is the system of transmitting telephone and television signals over long distances. Satellites orbiting the earth at a height of 35,700 km. above the Atlantic, Pacific and Indian Oceans provide a global coverage. They take exactly 24 hours to complete one orbit and so appear to stay in the same place. Telstar launched in the summer of 1969 took only 2.5 hours and was, therefore, within the range of the earth stations on each side of the Atlantic for very short periods. The global satellite system Intelsat (International Telecommunication Satellite Organization) was founded in 1964 to establish a worldwide system on a commercial basis. The first generation of Intelsat satellites to be launched from Florida was Early Bird, which went into service in June 1965. Further series have since been introduced. For example, in 1981 Intelsat had five satellites covering the Atlantic, Indian and Pacific Oceans. Post is now sent by satellite through Intel post, which began operating in 1980 and links New York City, Washington D.C., Toronto, Amsterdam, Bonn and London.
Television is the transmission of images of moving objects by radio. In a television system, all the details in a scene have to be transmitted separately and simultaneously and reassembled at such a speed that the eye cannot observe the building process. In 1926, the first practical demonstration of the television took place, when J.L. Baird (1888-1946) transmitted the radio moving pictures of living human voices over a short distance. In 1928, he produced the first television picture in colour, the high definition colour television picture in 1938 and in 1941, the large scale screen colour television receiver. Unfortunately, he always refused to accept that electronic transmission -a-pictures was essential rather than mechanical methods, so none of his inventions are now present in modern television sets. The BBC began televised programmes in 1930, the I.T.I. (Independent Television Authority) in 1955. The first television exchange across the Atlantic was made in July 1955 using the Telstar.
Radar is an abbreviation of Radio Detection and Ranging and it was S.M. Tucker of the US Navy who first used the term, (1940). The radar station sees an object because the invisible radio waves sent out from the transmitter are reflected from it and return to the receiver, which is able to detect them. Thus, radar is the use of radio signals that man broadcasts. It has proved of great service as an aid to aerial and marine navigation and in meteorology and astronomy. Radar astronomy investigates the Solar System with echoes of the signals sent out from the Earth.
Mobile telephones, Radio Paging, Electronic Mail, VSAT Services (Very Small Aperture Terminal), Electronic Data Interchange (EDI), Voice Mail and Video Conferencing have become very common today.
India is now undergoing a sea-change in the field of telecommunications. The national telex service is available between 70 cities sending and receiving printed messages direct from one subscriber to another. Our overseas communications service provides telegraph service to all and telephone, telex and radio photo services to almost every country in the world. According to the International Telecommunication Union, one per cent increase in telephone density will lead to three percent increase in the GDP (Gross Domestic Product). In the world, there are eight telephones per 100 people. In India there are 8 telephones for 1000 people. According to Shri N. Vittal, former Chairman Telecom Commission, the infrastructure this sector is growing at a most exciting rate. Many Indians in our big cities have started talking and working wireless. When the information superhighways are in place, anybody anywhere can reserve plane tickets, submit tax returns, play games and seek medical advice by tapping on their computer keys. Parts of the superhighways are already in place and more are under construction in the third largest emerging telecom market in the world. The Government of India dreams of wiring the country with a national information highway (NTH) by interlinking the existing network. The NIH may cost upto Rs. 40.000 crore. Such information highway will enable Indians to get high speed interactive multimedia and two-way communication facilities through a network that combines satellite, fiber optics, radio and wire line linkages. The government-owned National Informatics Centre (NIC) has brought thirty Indian cities into its own information superhighway. It will be expanded to cover seventy cities.
Mobile telephone service in India began on a limited scale in Delhi. The Government-owned Mahanagar Telephone Nigam Ltd., introduced it in the early eighties. Seeing the profitability aspect and the increasing desire among Indian businessmen for more state-of-the-art means of communication, the government decided that cellular telephones would be the first value-added services in the four metropolitan cities. Today mobile telephones have become so popular that they are offering stiff competition to fixed landlines.
Cellular phones will be followed by advanced radio paging services. The Department of Telecommunications (DOT) has finalized the list of companies, which will run the paging system in twenty-seven cities: One-can get anything from stock market prices to the weather report on the page screen by this system.
The radio paging services was first installed in Mumbai in 1992 by MTNL Champion Technology, a Hong Kong company, along with a consortium of Indian companies have already introduced Hindi-English pages and paging services.
VSAT service, Voice Mail, and Electronic Data Interchange, etc. have been installed in our cities in the past few years.
The rapid advance in the field of telecommunications has shrunk the world. In fact, it is making this world of ours a global village. It expedites the business in various fields.