Error checking and correction

• Explain how an even parity works (5)

  • number of 1s in data to be sent is counted.
  • parity bit set to 1 if binary data has an odd no of 1s
  • parity bit set to 0 if binary data has an even no of 1s
  • data is rechecked upon receival
  • odd means data is incorrect, even means data is correct
• Explain how an odd parity works (5)

  • numberof 1s in data to be sent is counted
  • parity set to 0 if data has odd no of 1s
  • parity set to 1 if data has even no of 1s
  • data is rechecked upon receival
  • even means data is incorrect, odd means data is correct
• What is majority voting

  A method of checking errors by producing the same data several times and checking its the same each time
• What is a check digit

  A digit added to the end of binary data to check the data has been sent correctly