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Telecommunications refers to wave-based communication technology through media such as air, cables etc. Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded drumbeats, lung-blown horns, or sent by loud whistles, for example. In the modern age of electricity and electronics, telecommunications now also includes the use of electrical devices such as telegraphs, telephones, and teleprinters, the use of radio and microwave communications, as well as fiber optics and their associated electronics, plus the use of orbiting satellites and the Internet.

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Orthogonal Frequency-Division Multiplexing (OFDM) — essentially identical to Coded OFDM (COFDM) — is a digital multi-carrier modulation scheme, which uses a large number of closely-spaced orthogonal sub-carriers. Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation) at a low symbol rate, maintaining data rates similar to conventional single-carrier modulation schemes in the same bandwidth. In practice, OFDM signals are generated using the Fast Fourier transform algorithm.

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A diagram of radio waves and radio transmission
Credit: LadyofHats

This diagram shows both the position of radio waves in the electromagnetic spectrum (logarithmic scale) as well as how radio waves are used for communication.

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Alexander Graham Bell.jpg

Alexander Graham Bell ( March 3,1847 – August 2, 1922 ) was an outstanding scientist, inventor, and innovator. Born and brought up in Scotland, he emigrated to Canada, and later, the United States. Over the years, his work and efforts were expressed between both countries. Bell is widely acclaimed as the prime developer of the telephone, with considerable honourable mention to Antonio Meucci and Philipp Reis. In addition to Bell's work in telecommunications, he was responsible for important advances in aviation and hydrofoil technology.

Did you know?

...that Intelsat 1, known as Early Bird, launched in 1965, provided either 240 voice circuits or one two-way television channel between the United States and Europe.

...that the first telephone message was transmitted in 1876 from one room in Alexander Graham Bell’s house to another.

...that in 1880 France rewarded Bell the Volta Prize, worth 50,000 francs, for his invention.


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