Error Detection and Error Correction

1. 10.1
Error Detection
and
Error Correction
Md Mosharof Hosen
CSE dept.

2. 1
Introduction
Error detection is the detection of errors caused by
noise or other impairments during transmission from
the transmitter to the receiver.
Error correction is the detection of errors and
reconstruction of the original, error free data.

3. 2
Types of Errors
 Single bit error :
-Only one bit in the data unit has changed.
 Burst error :
- It means that two or more bits in the data
unit has changed.

4. 3
Single-bit error
Only one bit in the data unit has changed.

5. 4
Burst error
means two or more bits in the data unit has
changed.

6. 5
Error detection/correction
 Error detection
-Check if any error has occurred
-Don’t care the number of errors
-Don’t care the positions of errors
 Error correction
-Need to know the number of errors
-Need to know the positions of errors
-More difficult

7. 6
Using Hamming Method
 Hamming code is a popular error detection and error
correction method in data communication.
 Hamming code can only detect 2 bit error and correct a
single bit error which means it is unable to correct burst
errors if may occur while transmission of data.

8. 7
Continue . . .
Where r is the number of redundant bits required and
m is the number of data bits.
R is calculated by putting r = 1, 2, 3 … until the above
equation becomes true.
R1 bit is appended at position 20
R2 bit is appended at position 21
R3 bit is appended at position 22 and so on.

9. 8
We can count the number of 1s in the Xoring of two
words
1. The Hamming distance d(000, 011) is 2 because
2. The Hamming distance d(10101, 11110) is 3 because

10. 9
Geometric concept for finding dmin in error detection

11. 10
Geometric concept for finding dmin in error correction
To guarantee correction of up to t errors in all cases,
the minimum Hamming distance in a block code must
be dmin = 2t + 1.

12. 11
Design Screenshot

13. Thanks to all