Comp science chapter 2.2 method of error detection

• What is the risk associated with data transmission?


  Data may be corrupted, lost, or gained.
• What are the main causes of errors during data transmission?

  1. Interference
  2. Problems during packet switching
  3. Skewing of data
• What is interference in the context of data transmission?


  Interference refers to electrical disruptions that can corrupt or lose data.
• How can packet switching lead to data loss?


  Packet switching can lead to data loss or even gain data during transmission.
• What is skewing of data?


  Skewing occurs during parallel data transmission when bits arrive out of synchronization.
• What are the methods of error detection and correction?

  1. Checksums
  2. Parity check
  3. Automatic Repeat Requests (ARQ)
  4. Check digit
• What is a checksum?


  A checksum is a value used to verify if data has changed or been corrupted after transmission.
• Describe the checksum process.


  1. Sender calculates checksum using an algorithm.
  2. Checksum is transmitted with data.
  3. Receiver recalculates checksum.
  4. Checksum comparison determines if errors occurred.
• What is a parity check?


  A parity check is a method to determine if data has been changed or corrupted during transmission.
• What are the two types of parity?


  1. Even parity
  2. Odd parity
• What does the Most Significant Bit (MSB) represent in parity checks?


  The MSB is reserved for the parity bit.
• How do you determine the parity bit for the data 1101101 using even parity?


  The parity bit is 0 to keep the number of 1s even.
• How do you determine the parity bit for the data 1101101 using odd parity?


  The parity bit is 1 to make the number of 1s odd.
• What is a limitation of parity checks?


  If two bits change value, it may be impossible to locate the error using parity checking.
• What is Automatic Repeat Request (ARQ)?


  • A method to check data after transmission.
  • Uses positive/negative acknowledgements and timeouts.
  • Ensures data integrity in mobile networks.
• How does ARQ ensure data integrity?


  ARQ uses error detection codes and acknowledgements to confirm data integrity.
• What types of errors can check digits detect?


  • Transcription errors
  • Transposition errors
• Describe the steps to calculate a check digit for ISBN-13.


  1. Sum odd-numbered digits.
  2. Sum even-numbered digits and multiply by 3.
  3. Add results and divide by 10.
  4. Determine check digit based on remainder.