Analogue & Digital Data (Cambridge International IGCSE ICT)

Spec point — 1.1.3

Analogue & Digital Data

What is analogue data?

• Analogue data is continuous data created from non-digital devices

• Analogue data can change gradually and smoothly

• Examples of analogue data include:

  • sound waves produced when you talk
  • data collected by sensors (output)

What is digital data?

• Digital data is data represented in a binary format(1s and 0s)

• Digital data is created and/or stored using digital devices

• Examples of digital data include:

  • software
  • documents/files

Characteristics of analogue & digital data

Analogue to digital conversion (ADC)

• Analogue data **must be converted **to digital data so that it can be processed by a computer
• The ADC process involves** taking samples** (measurements) of the analogue signal and converting it to a binary code
• The sample rate and a higher number of binary digits used in the conversion leads to a more accurate representation of the original signal, but, takes up more space on secondary storage

Digital to analogue conversion (DAC)

• Digital data must be converted to analogue data so that it can be used to control devices
• The DAC process involves converting discrete digital values (1s and 0s) back into a continuous analogue signal
• The quality of the analogue signal after conversion is based on the original sample rate and number of bits used in the digital data

Worked Example A greenhouse is used to grow plants and is computer controlled. Give two reasons why data from the sensors needs to be converted for use by a computer.

[2]

Answer

Two of:

Final answer: So that the data from the sensor can be understood by the computer [1]

Final answer: The output from a sensor is analogue [1]

Final answer: The input to the computer is digital [1]