Question

Using an example, illustrate how checksum is used in error correction and detection. 

Answer 1

Checksum

This is a method of error detection method in transmitted data. This involves the idea of computing checksum on the data values to be transmitted. Upon receiving the data at the receiver’s end, a checksum is computed and a comparison made from previous one and if there is a mismatch then an error in transmission has occurred.

Example

A sender may send want the following 4 frames:11001100, 10101010, 11110000 and 11000011.Therefore, he computes 1’s complement and if there is a carry over, it is added to the sum. The sender complements the sum after adding the four frames to get a checksum of 11010011, and this value is sent along with the data frames. Upon receiving, the receiver computes a 1s complement to the frames with the checksum included and the obtained result is complemented. If the result obtained after complement is 0, then an error has not occurred during transmission