Analogue and Digital Data

Analogue and Digital Data

1. Analogue

   • The waves move through pressure in the air
   • Analogue data can vary continuously within a range of values
     • The temperature in a greenhouse
     • A person's height or mass
     • Sound frequencies
   • Sound is represented through wave forms
   • Transmitted through waves
   • Modulation
     • Frequency modulation
       • The radio wave varies in frequency to match the changes in the sound wave
     • Amplitude Modulation
       • The radio wave varies in amplitude to match the changes in the sound wave

2. Digital

   • Move through electrical signals
   • Process data in the form of digits 0s and 1s
     • E.g. Off and On
     • Only two states
   • Images inside a computer are stored as numeric values
     • Different values for different coloured pixels
   • Text that you type into a computer is stored as numeric codes
   • Digital data can only have distinct values
     • A light switch can either be on or off
     • The number of cars passing a point in a road
     • The number of people attending a football match
   • Typically created using 16-bit samples over a spectrum of 44.1KHz
   • Stereo sound doubles the number of samples taken
     • 44,100 samples per second would now take 32 bits each
     • CD quality sound requires 1.4 million bits of data per second
   • The coded information controls the short bursts of waves produced by a source
   • Digital Audio Broadcast radio (DAB Radio)
     • Transmitted as digital signals
   • Advantages
     • Digital signals carry more information per second than analogue signals
     • They maintain their quality over long distances better than analogue signals

3. Analogue to Digital Convertor (ADC)

   • E.g. Microphone
     • converts the analogue signals from the microphone into digital data that the computer can then process.
     • Converts the audio picked up by the microphone (your voice) and uses an ADC to convert it into numbers
       • This results in the computer being able to understand the data

4. Digital to Analogue Convertor (DAC)

   • E.g. Speakers or Headphones
     • takes digital data from the computer
       • converts it into analogue signals which the speakers or headphones converts into sound.
   • E.g. MP3 Player

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