10 error detectio9n and correction

Question 1

types of error

Answer 1

Single bit Error : Means that only 1 bit of a given data unit is changed from 1 to 0 or 0 to 1.
Burst Error: Means that 2 or more bits in the data unit have changed from 0 to 1 or from 1 to 0.

Question 2

redundancy

Answer 2

Detecting or correcting errors is redundancy.
These redundant bits are added by sender and removed by the receiver.

Question 3

what is error and correction

Answer 3

The correction of error is more difficult than the detection.
In the error detection, we are interested in error has occurred or not.
In error correction, we need to know exact number of bits that are corrupted, and more importantly their location in the message.

Question 4

block coding

Answer 4

we didivde our message into blocks. each of k bits, called datawords. We add r redundant bits to each block to make the length n = k + r. The resulting n-bit blocks are called codewords.

Question 5

error detection

Answer 5

we use a generator. the dataword is extracted

Question 6

hamming distance

Answer 6

The Hamming distance between two words is the number of differences between corresponding bits.

• XOR operation and count number’s of 1

Question 7

pairty check code

Answer 7

A simple parity-check code can detect an odd number ones as errors.