Error Detecting Codes & Error Correcting Codes | Unit-1 #13
Error Detecting Codes:
• When binary data is transmitted and processed, it is susceptible to noise that can alter or distort its contents.
• The 1s may get changed to 0s and 0s to 1s.
• Several schemes have been devised to detect the occurrence of a single-bit error in a binary word so that whenever such an error occurs the concerned binary word can be corrected and retransmitted.
Parity:
• There are two types of parity – odd parity and even parity.
• For odd parity, the parity bit is set to a 0 or a 1 at the transmitter such that the total number of 1 bit in a word including the parity bit is an odd number.
• For even parity, the parity bit is set to a 0 or a 1 at the transmitter such that the total number of 1 bit in a word including the parity bit is an even number.
Block Parity:
• When several binary words are transmitted or stored in succession, the resulting collection of bits can be regarded as a block of data, having rows and columns.
• Parity bits can then be assigned to both rows and columns.
• This scheme makes it possible to correct any single error occurring in a data word and to detect any two errors in a word.
• This technique also called word parity, is widely used for data stored on magnetic tapes.
Error Correcting Codes:
• A code is said to be an error-correcting code if the correct code word can always be deducted from an erroneous word.
• A code with a minimum distance of three can not only correct single-bit errors but also detect (but cannot correct) two-bit errors.
• If the location of error correction is determined, then by complementing the erroneous digit, the message can be corrected.
• 7-bit hamming code is one type of error-correcting code.
GTU - Computer Engineering (CE) - Semester 3 - 3130704 - Digital Fundamentals - Fundamentals of Digital systems & Logic families - Error Detecting Codes - Error Correcting Codes
Digital Fundamentals PPTs are available here: http://www.darshan.ac.in/DIET/CE/GTU-...
This video is recorded by Prof. Krunal Vyas ([email protected], +91-9601901005) at the Computer Engineering Department of Darshan Institute of Engineering & Technology, Rajkot as per GTU Syllabus.
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