Longitudinal redundancy check

Longitudinal parity check (English longitudinal redundancy check, thus often LRC ) is a method for detecting one -bit errors in digital data transmission.

After a certain number of transmitted data words an additional parity data word is transmitted, which generates column-wise parity. This means that depending on the agreement must make up the corresponding sum over a column of a straight ( even parity ) or odd number (uneven parity). This is not the case, in which a transmission error has occurred. If when transmitting two bit errors occur in the same column, this can not be determined by this parity check method, since then satisfy the column sums the specifications. The following example shows three bytes and the associated parity byte for the production of columns of the same parity.

11011001 10111001 00110011 -------- 01010011 → parity data word -------- 22242024 → column sums