Parity check codes k Data bits r Check bits Each parity check is a modulo 2 sum of some of the data bits Example: X1 +++ t x t xParity check codes k Data bits r Check bits • Each parity check is a modulo 2 sum of some of the data bits Example: c1 = x1 + x 2 + x3 c 2 = x 2 + x 3 + x4 c 3 = x1 + x 2 + x4