Parity check

Parity Check

Parity check is a method used to detect errors in data transmission. It involves adding an extra bit to a binary code to ensure that the total number of ones in the sequence is always odd (or even, depending on the type of parity used). If the number of ones in the transmitted data does not match the expected parity, an error is assumed to have occurred during transmission.

How Parity Check Works

Parity check is a simple error detection technique that is commonly used in data transmission protocols to ensure the integrity of data. It works by adding an additional bit, known as the parity bit, to a binary code. The parity bit is calculated based on the number of ones in the binary sequence.

• Even Parity: In even parity, the number of ones in the binary sequence, including the parity bit, should always be an even number. If the number of ones is not even, an error is assumed to have occurred during transmission.
• Odd Parity: In odd parity, the number of ones in the binary sequence, including the parity bit, should always be an odd number. If the number of ones is not odd, an error is assumed to have occurred during transmission.

When the data is transmitted, the parity bit is appended to the binary sequence to ensure that the total number of ones satisfies the chosen parity type. For example, if even parity is used, the parity bit is set to 0 if the total number of ones in the sequence (including the parity bit) is already even. If the total number of ones is odd, the parity bit is set to 1 to make the total number of ones even.

Upon receiving the data, the recipient recalculates the parity by counting the number of ones in the received sequence, including the parity bit. The recipient then checks if the calculated parity matches the transmitted parity bit. If there is a mismatch, the recipient flags an error, indicating that an error occurred during transmission.

By implementing parity checking in data transmission protocols, data integrity can be ensured to a certain extent. However, it is important to note that parity check only detects errors and does not provide any means for error correction. If an error is detected, the recipient can request retransmission of the data or take corrective actions based on the specific protocol in use.

Prevention Tips

• Implement parity checking in data transmission protocols to ensure data integrity.
• Use error-detection codes like parity bits to catch transmission errors and take corrective actions.

Related Terms

• Error Detection Codes: Methods used to detect errors in data transmission. Error detection codes, including parity check, play a crucial role in ensuring the accuracy and integrity of data during transmission.
• Checksum: A value used to verify the integrity of data, often used in error detection. Checksums are calculated based on the data being transmitted and are compared to the received checksum to detect any errors in the transmission. While checksums are more complex than parity bits, they provide a higher level of error detection capabilities.