Analogue and Digital Signals

Gap-fill exercise

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Analogue signals vary continuously in . They use less circuitry than digital circuits, but the signals are more likely to suffer from by external sources. Examples of naturally occuring signals include changes in light levels, temperature, sound levels, electric and fields.


Analogue clockDigital Clock

The analogue clock has a movement of the hands, but this digital clock display only changes every .

Transmission of information using analogue signals is less secure than using digital tranmissions. Digital signals are easy to , making it more difficult for unauthorised users to gain access. Digital signals only have two values. This is often called a signal. The off state is given a value of 0 and the on state is given a value of . Digital signals are used in modern communications including mobile , and satellite communications.


Analogue clock

Most television signals will soon be . This image shows a , which allows digital signals to be received.

use digital signals, and the information is easily stored on hard drives or usb drives.


Digital storage cardDigital camera

Large amounts of digital information can now be stored in a small space, using memory . These are widely used used in digital

Digital circuitry is often more complex, and can use more energy than analogue circuits. They are usually more , especially when produced in small quantities.


Optical Fibre

Transmission of digital signals can be achieved using fibres. In this process the electrical signals are converted into pulses of visible light or light. This involves the use of to digital circuits.

Optical Fibre 2

Optical fibres use the phenomenon of total internal , as the light is transmitted within the fibres. This is shown in the diagam above. The angle of incidence must be greater than the angle for light to be transmitted along the fibre. Optical fibres are much to produce than heavier, copper cables. Digital signal allow a greater amount of information to be transmitted in a given , compared with analogue signals.