Error Detection And Correction Methods-Cont

First a string of n 0's is appended to the data unit The number 'n' is one less than the number of bits in the predetermined divisor, which is n+1 bits Secondly,  newly  elongated  data  unit  is  divided  by  the  divisor  using   a  process  called binary division. The remainder resulting from this division is the CRC Third,the CRC of 'n' bits replaces the appended 0's at the end of the data unit Note that CRC may consist of all zeros The data unit arrives at the receiver followed by the CRC The receiver treats the whole string as a unit and divides it by the same divisor that was used to find the CRC remainder If string arrives without an error, the CRC checker yields a remainder of zero and data unit passes If the string has been changed in transit, the division yields a non-zero remainder and the data unit does not pass The CRC Generator Uses Modulo-2 Division The CRC Checker ŠFunctions exactly like CRC Generator