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Infrared light, microwaves and radio waves are all used to transmit information such as computer data, telephone calls and TV signals. Optical fibres can carry information coded in light or infrared signals. Optical fibres can carry more information than an ordinary cable of the same diameter. Analogue signals vary continuously in amplitude and frequency. Digital signals are a series of pulses with two states – on or off. Digital signals carry more information per second than analogue signals, and they maintain their quality better over long distances. » Using EM waves
to send information
[ This page has been adapted from www.bbc.co.uk/schools/gcsebitesize/science
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