telecommunications

telecommunications Technology involved in the sending of information over a distance. The information comes in a variety of forms, such as digital signals, sounds, printed words, or images. The sending is achieved through telegraph, telephone or radio, and the medium may be wires or electromagnetic (radio) waves, or a combination of the two. There are two basic types of message: digital signals, in which the message is converted into simple, coded pulses and then sent (as in Morse code); and analogue signals, in which the message – for example, a human voice – is converted into a series of electrical pulses that are similar in wave form to the modulations of the original message. See also fax; satellite, who inaugurated (1844) the first public line – between Washington and Baltimore. In 1866, the first permanently successful telegraph cable was laid across the Atlantic. In 1875, Thomas Edison invented a method of transmitting several messages simultaneously over the same wire.