Encoding and Decoding

Encoding and Decoding

• 1.
  Encoding and decoding analogand digital signals
• 2.
  Encoding involves convertingdata from its original form into another form for transmission. Decoding is the reverse process.
• 3.
  Analog data isrepresented by using continuous variable physical quantities, such as voltages.
• 4.
  For example, awatch that displays the time by hands moving smoothly around the clock face is an analog device.
• 5.
  Most natural eventsin the real world, such as temperature, light and pressure, are in analog form.
• 6.
  For example, adigital clock shows the time as a certain number of hours and minutes. Digital data is represented in the form of digits or numbers.
• 7.
  Information technology works withdata in a digital form.
• 8.
  Digital signals arerepresented as a series of 0s and 1s.
• 9.
  The form ofthe 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.
  The quality ofanalog 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.
  However, digital datais 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.
  There are fourencoding 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.
  Information technology works withdata in a digital form.
• 14.
  Analog data toanalog 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.
  Digital data toanalog 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.
  A modem encodesdigital data to analog signals and decodes analog signals to digital data.
• 17.
  Analog data todigital 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.
  Images are digitisedusing such devices as scanners, and sounds are digitised using a process called sampling.