3.3 TELECOMMUNICATION What is telecommunication? Definition Telecommunication is the transmission of signals over long distances for communication purposes. After the discovery of electricity, telecommunication developed with the invention of the telegraph, the telephone, and the radio . Nowadays, we also use mobile phones, TVs, and computers to send words, images, texts, and sounds. 1 2 Telecommunication happens in two ways: through , such as wires and cables; physical media , through electromagnetic waves. wirelessly DO The prefix "tele-" comes from ancient Greek and can be found in other words, such as “television.” Can you guess its meaning? Can you think of other words containing this prefix? 1 DO Split up into groups and search the Internet for information about the inventor (and the period) of the telegraph, the telephone, and the radio. 2 The basic elements of telecommunication Telecommunication normally needs three basic elements: – a device that transmits the information; a transmitter – the channel that carries the signal, which can be a physical medium, such as an electrical cable, or electromagnetic radiation travelling through space, as is the case for radio signals; a transmission medium – a device that receives the signal from the channel and transforms it into information that can be understood. a receiver Some devices – such as antennas, mobile phone cells, and satellites – can function both as transmitters and receivers; for this reason, they are called . transceivers Analogue and digital transmission To be transmitted, the information must be transformed into signals that can be or : analogue digital was the first type of data transmission in the history of telecommunication. However, the disadvantage of analogue signals is that they can be easily distorted by interference or . Analogue transmission noise means transforming an analogue signal into a series of bits to transmit them in discrete quantities. This prevents the risk of interference or degradation . The number of bits transmitted in a second defines the quality of the transmission. Digital transmission 1 MORE Revise the difference between analogue and digital signals in Section 3, Unit 2. 1