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Analogue v digital

You should be able to explain why digital signals maintain their quality better than analogue signals.

Noise

All signals become weaker as they travel long distances, and they may also pick up random extra signals. This is called noise, and it is heard as crackles and hiss on radio programmes. Noise may also cause an internet connection to drop or slow down, as the modem tries to compensate.

Analogue signals

Noise adds extra random information to analogue signals. Each time the signal is amplified, the noise is also amplified. Gradually, the signal becomes less and less like the original signal. Eventually, it may be impossible to make out the music in a radio broadcast against the background noise, for example.

Digital signals

Noise also adds extra random information to digital signals. However, this noise is usually lower in amplitude than the amplitude of the ON states. As a result, the electronics in the amplifiers can ignore the noise and it does not get passed along. This means that the quality of the signal is maintained, which is one reason why television and radio broadcasters are gradually changing from analogue to digital transmissions.

They can also squeeze in more programmes, because digital signals can carry more information per second than analogue signals.

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