Analogue and digital signals

Seite 1

Information is converted into signals.

To communicate any kind of information (e.g. sound or picture), it needs to be converted into electrical signals before its transmitted.

These signals can then be sent long distances down telephone wires or carried on FM waves.

These signals can either be analogue or digital.

Analogue signals vary but digital’s just on or off.

An analogue signals can take any value with a certain range. (Remember: analogue – any). The amplitude and frequency of an analogue wave wary continuously.

A digital signal can only take two values. These values tends to be called ‘on/off’, or ‘1/0. For example, you can send data along optical fibres as short pulses of light.

Digital signals have advantages over analogue.

Digital and analogue signals weaken as they travel, so they might need to be amplified along their routes.

They also pick up interference or noise from electrical disturbances or other signals.

When you amplify an analogue signal, the noise is amplified too – so every time it’s amplified, the signals loses quality. The noise is easier to remove or ignore with digital, so the signal remains of high quality.

Interference.

When two or more waves of a similar frequency meet, they can create one combined signal with a new amplitude.

This is called interference. You get it when two radio stations transmit on similar frequencies.

Another advantage of digital technology is that you can transmit several signals at the same time using just one cable or EM wave – this is called multiplexing.

Multiplexing happens in phone wires. When you’re on the phone, your voice is converted into a digital signal and transmitted regularly at very small time intervals. In between your voice signals beings transmitted, thousands of other people’s voice end so the person you called can hear you – and only you. This happens do quickly you don’t notice it.

The advantages of digital signals over analogue played a big part in the ‘switching over’ from analogue to digital TV and radio broadcasts.