Encoding and Decoding


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Encoding and Decoding analog and digital signals

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Encoding and Decoding

  1. 1. Encoding and decoding analog and digital signals
  2. 2. Encoding involves converting data from its original form into another form for transmission. Decoding is the reverse process.
  3. 3. Analog data is represented by using continuous variable physical quantities, such as voltages.
  4. 4. For example, a watch that displays the time by hands moving smoothly around the clock face is an analog device.
  5. 5. Most natural events in the real world, such as temperature, light and pressure, are in analog form.
  6. 6. For example, a digital clock shows the time as a certain number of hours and minutes. Digital data is represented in the form of digits or numbers.
  7. 7. Information technology works with data in a digital form.
  8. 8. Digital signals are represented as a series of 0s and 1s.
  9. 9. The form of the data (either analog or digital) and the transmission signal (either analog or digital signal) affects the quality of the data received and the cost of transmission.
  10. 10. The quality of analog data depends on maintaining the exact wave as it moves through a wire or space. If it is corrupted in any way, there is no way of regenerating the wave.
  11. 11. However, digital data is transmitted as a series of 0s and 1s, and it is possible to regenerate data that has been corrupted. That is, to reconstruct the data, it is only necessary to distinguish between a 0 and a 1.
  12. 12. There are four encoding and decoding possibilities in transmission: • Analog data to analog signal. • Digital data to analog signal. • Digital data to digital signal. • Analog data to digital signal.
  13. 13. Information technology works with data in a digital form.
  14. 14. Analog data to analog signal. The wave shape of the data is encoded into the signal. A telephone encodes analog data in the form of sounds into analog signals suitable for the telephone line. If the signal is corrupted, there is no way of restoring the original analog data.
  15. 15. Digital data to analog signal. A series of 0s and 1s is encoded into a continuous wave. A modem encodes (or modulates) digital data from a computer into analog signals for the telephone line. When the analog signal is received by another modem, it decodes (or demodulates) the analog signal into digital data.
  16. 16. A modem encodes digital data to analog signals and decodes analog signals to digital data.
  17. 17. Analog data to digital signal—the wave shape of the data is encoded into a series of 0s and 1s. This process of generating digits or numbers is called digitising.
  18. 18. Images are digitised using such devices as scanners, and sounds are digitised using a process called sampling.