Therefore, the number of redundancy bits = 4 Example −Ĭonstruct the even parity Hamming code word for a data byte 1001101. Note − Set the parity bit 1 if the total number of 1s in the positions it checks odd or set the parity bit 0 if the total number of 1s in the positions it checks even. Position 4 − Check 4 bit, then skip 4 bit, check 4 bit, then skip 4 bit (Ex − 4, 5, 6, 7, 12, 13, 14, 15, etc.).Position 1 − Check 1 bit, then skip 1 bit, check 1 bit and then skip 1 bit and so on (Ex − 1,3,5,7,11, etc.).The position of the parity determines the sequence of bits that it alternatively checks and skips. Step 3 − All other bit positions are for the data to be encoded using (3, 5, 6, 7, 9, 10 and 11, etc.)Įach parity bit calculates the parity for some of the bits in the code word.Step 2 − Mark all the bit positions that are powers of two as parity bits (1, 2, 4, 8, 16, 32, 64, etc.).Step 1 − First write the bit positions starting from 1 in a binary form (1, 10, 11,100, etc.).The hamming method uses the extra parity bits to allow the identification of a single-bit error. Where R = Redundant bit, and M = data bit. So, the number of redundant bits (R) that represent all states (M+R+1) must satisfy − The following formula is used to find the number of redundant bits. An N-bit unit containing data and the check bit is often referred to as an N-bit codeword. Suppose the total length of the frame be N (N=M+R). A-frame consists of M data bits and R redundant bits.
The redundancy bits are placed at certain calculated positions to eliminate the errors and the distance between the two redundancy bits is called "Hamming Distance".Įrror Correction Code − This is the relationship between data bits and redundancy bits to correct a single-bit error. Redundant bits are extra binary bits that are generated and added to the information-carrying bits of data transfer to ensure that no bits were lost during the data transfer. The hamming method corrects the error by finding the state at which the error has occurred.
In Computer Networks, Hamming code is used for the set of error-correction codes which may occur when the data is moved from the sender to the receiver.
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