Vertical redundancy check
The vertical redundancy check ( English vertical redundancy check , therefore often VRC or also cross parity check ) is a method for error detection by means of redundancy information transmitted in addition to each character. A very common method is the transmission of a parity bit (also called parity bit) in digital data transmission .
Example: parity bit
An additional bit (parity bit) is appended to each data word so that parity is created. This means that the checksum over the individual bits of the data word must result in an even (same parity) or odd (unequal parity) number. In this way, 1-bit errors can be detected during data transmission. If two bit errors occur at the same time, this cannot be detected with the parity check method. The following example shows some 8-bit data words with attached parity bits (shown in red) to produce the same parity:
11011101|0 (Quersumme: 6) 10111001|1 (Quersumme: 5) 00110011|0 (Quersumme: 4)