2. Analogue and Digital Data

3. Analogue Data Water flowing down a stream is uncountable.  Data obtained by measurement is called continuous/analogue data.  Continuous data can take one of an infinite number of states.  A device which can be set to an infinite number of continuously changing states is called an analogue device.

4. Digital Data Consider a dropping water tap. We can count the number of drops falling per minute.  Data obtained by a set of countable pulses, is called discrete/digital data.  Discrete data can take one of a fixed number of states.  A device which can be set to a number of different separate values/states is called a digital device.

5. Are Sound Signals Analogue or Digital? Sound signals are analogue signals since sound can take various frequencies.

6. Ex. of use of Sound In Computers Input of sound through a Microphone Output of sound through speakers Sounds downloaded from internet

7. How is sound data (Analogue) inputted in computers (Digital)? Sound data is digitised before it is stored/processed by a computer This is done using an analogue-to-digital converter (ADC) Analogue-to- digital converter

8. Purpose of the Analogue-to-digital Converter Analogue-to- digital converter

9. How is sound data outputted from computers? Digital data for sound in computers has to be converted into analogue signals if it is to be outputted to speakers This is done using an digital-to-analogue converter (DAC) Digital-to- Analogue converter

10. Purpose of the Analogue-to-digital Converter Digital-to- Analogue converter