Analogue and digital
In analogue technology, a wave is recorded or used in its original form. The word 'analogue' comes from the Greek word analogos, which means ‘proportionate’. In other words, what you put in will be the same in amount, magnitude or degree to the output.
Analogue television refers to broadcasts where the picture information is transmitted using an analogue signal, by varying the voltage or frequency of radio waves. Such signals, however, can be easily interrupted by other signals and become distorted or inaccurate. This is why the world is moving towards digital technology.
Digital technology converts analogue signals into a binary form. This means the information from the analogue signal is turned into numbers, and stored into the digital device. To retrieve the information (such as sound or images), the numbers are then turned into waves that are very similar to the original waves.
Digital television refers to broadcasts where the information is transmitted using digital encoding. This promises sharper and better quality pictures and better quality sound. It also means that the information does not degrade over time because as long as the numbers can be read, the same wave can be reproduced. Digital signals do not get distorted as a result. They also take up much less bandwidth than analogue signals.
Using less radio bandwidth per television channel, digital broadcasts allow several channels to be sent using the same amount of radio spectrum as a single analogue channel. They also require less power to transmit and do not suffer from the same level of interference, which you might see as ‘snow’ on the screen or hear as white noise.
To receive digital broadcasts, households require a digital television or a set top box attached to their analogue television to interpret the signals. They may also require a new television aerial.
Digital television broadcasts began in Australia in 2001 in Sydney, Melbourne, Brisbane, Adelaide and Perth. The Commonwealth Government has legislated to turn off analogue television in the future and only allow the use of digital broadcasts; however the slow adoption of digital television has seen the deadline for this changeover be reviewed.
Learn more about digital and analogue television