INFORMATION TECHNOLOGY

Analogue or digital
Signals can either be analogue or digital. In an analogue signal, the signal is varied continuously with respect to the information. In a digital signal, the information is encoded as a set of discrete values (e.g. 1's and 0's). Telecommunication devices convert different types of information, such as sound and video, into electrical or optical signals. Electrical signals typically travel along a medium such as copper wire or are carried over the air as electromagnetic waves. Optical signals typically travel along a medium such as strands of glass fibre. When a signal reaches its destination, the receiver converts the signal back into a form suitable for human interpretation (e.g. sound for a telephone, moving images for a television, or words and pictures for a computer screen).