Digital & Analogue Signals (Cambridge (CIE) IGCSE Physics)

Digital & analogue signals

Extended tier only

• There are two types of signals:

  • Analogue

  • Digital

• Analogue signals vary continuously - they can take any value

 An analogue signal

An analogue signal is continuously varying, taking any value

• A digital signal can only take one of two (discrete) states

  • These are usually referred to as;

    • 1s and 0s

    • Highs and lows, or

    • Ons and offs

 A digital signal

A digital signal can only take one of two values – 0 or 1

Transmission of sound

Extended tier only

• Sound waves that can be transmitted as a digital or analogue signal

• Signals for speech or music are made up of varying frequencies

  • To make out the information clearly, the signal needs to be transmitted with as little interference as possible

• The signal undergoes digital sampling

• It is converted both before transmission and after being received

  • Before transmission: the signal is converted from analogue to digital

  • After being received: the signal is converted back from digital to analogue

Benefits of digital signalling

Extended tier only

• The benefits of digitally sampling a signal include:

  • Increased rate of data transmission

  • Increased range due to accurate signal regeneration

Digital sampling an analogue signal

Analogue v digital signal

• The key advantages of data transmission in digital form compared to analogue are:

  • The signal can be regenerated so there is minimal noise

  • Due to accurate signal regeneration, the range of digital signals is larger than the range of analogue signals (they can cover larger distances)

  • Digital signals enable an increased rate of transmission of data compared to analogue

  • Extra data can be added so that the signal can be checked for errors