2021-05-11 Error Detection

-Parity Checking ( odd/even parity )

single bit parity

two-dimensional bit parity

 

-Checksum

 

-CRC cyclic redundancy check

view data bits, D, as a binary number

choose r+1 bit pattern (generator), G

goal: choose r CRC bits, R, such that

    • <D,R> exactly divisible by G (modulo 2)

    • receiver knows G, divides <D,R> by G. If non-zero remainder: error detected!

    • can detect all burst errors less than r+1 bits

CRC example: