Analogue And Digital Signals

Front 1

How is information (pictures, sound) transmitted over long distances?

Back 1

needs to be converted into electrical signals before its transmitted.
Signals sent down telephone wires or on EM waves.
Signals must be analogue or digital.

Front 2

How do analogue and digital signals vary?

Back 2

Analogue signals can vary within a certain range (amplitude and frequency) .
Digital signal is one of two values (on or off or 1/0).

Front 3

What are the advantages of digital signals?

Back 3

Both digital and analogue weaken over long distances.
They also pick up interference or noise from electrical disturbances or other signals.
When amplified (to make stronger again) the noise is amplified again too and signal loses quality.
Digital signal noise is ignored so remains high quality.

Front 4

What is interference?

Back 4

When two or more signals have a similar frequency can create a single signal with new amplitude.

Front 5

Why don't digital signals suffer from interference?

Back 5

With digital noise is just ignored so remains high quality.
consequently, easier to transmit multiple signals using one cable (multiplexing).

Front 6

What is quantisation?

Back 6

process of rounding multiple values to smaller set. loses lots of info with analogue (see diagram)