Greetings!We have recently published 100+ articles on android tutorials with kotlin and java. If you need, you may visit page. You can also check. Also, if you are interested in content writing, you can mail us at [email protected] the next few set of tutorials, we will study about Error Control methods used in computer networking. We will look at the types of errors and the ways the errors can be corrected or detected. In this tutorial, we will study about hamming code and hamming distance in greater detail. What is an Error?While sending data from a sender to a receiver, there is a possibility that the data bits may change or get corrupted.
This change or corruption of data bits is called an error. Types of ErrorsErrors can be of two types:.
Hamming Code Implementation in C July 01, 2018 Hey guys i am uploading this program i made in my college today,its simple hamming code word generation program for N bits data you enter and it will show you the code word:). I used the linear algebra definition supplied by Wikipedia ('Hamming Code (7,4)'). At several points in the program, I printed the variable contents, but fixing one problem lead to another. To verify if the output was correct, I compared it to the example available on Wikipedia, and the result produced by an online calculator.
Burst errors: More than one bit is corrupted. Single bit errors: Only one bit is corruptedHow to Handle the Errors?While sending the data, the data packets may get lost due to congestion.
Thus, we need methods to handle errors. Error can be handled in two ways –. Error Correction.
Error DetectionNow, let us look at the two techniques in greater detail. Error Correction TechniqueIn the error correction technique, the error can be detected and the location of error is also known. Thus, it is possible to correct the detected error. One of the methods of error correction is the hamming code.A parity bit, or check bit, is a bit added to a string of binary code to ensure that the total number of 1-bits in the string is even or odd.In this tutorial, we will assume even number of 1-bits. Hamming codeLet us understand hamming code error correction through an example.
Assume,Data = 10011010No of parity bits to be added to data: = m + r + 1. (i)where,r = number of parity bits,m = number of message bitsUsing hit and trial method, we will find the value of ‘r’.Let’s assume we first take r = 4.Now, using equation (i)= 8 + 4 + 1 (Therefore, the inequality holds)Now, once we get the value of ‘r’, we know the no. Of parity bits to add in the data. The parity bits are added at power of 2’s position. For example, position will be 1st ( ), 2nd ( ), 4th ( ), 8th ( ) and so on.Now, total bits that will be sent to the receiver will be the message bits + parity bits. So, final bits will be 1 0 0 1 1 0 1 0.To find the parity bits, we start from position.
We take ‘i’ bits and leave the next ‘i’ bits. Then, again consider the next ‘i’ bits and continue the process till the last bit. Finding parity bits at the Sender’s Side. Error correction Drawback of Hamming Code:. Correct only single bit errorsFinding the hamming distance: (BITWISE XOR)Hamming distance between two numbers is equal to number of positions at which the corresponding symbols are different.We can find the hamming distance by using XOR operation.
For example,Hamming distance between two numbers (10101010 and 10101101) is –1 0 1 0 1 0 1 01 0 1 0 1 1 0 1———————–0 0 0 0 0 1 1 1———————–The no of 1’s gives the hamming distance.Note:– To correct ‘d’ bits, hamming distance should be equal to 2d + 1.– To detect ‘d’ bits, hamming distance should be equal to d + 1.That’s end of tutorial on hamming code tutorial. We also discussed about hamming distance in greater detail. Now, we will see the error detection techniques in the next tutorials.
Like other error-correction code, Hamming code makes use of the concept of and s, which are bits that are added to data so that the validity of the data can be checked when it is read or after it has been received in a data transmission. Using more than one parity bit, an error-correction code can not only identify a single bit error in the data unit, but also its location in the data unit.In data transmission, the ability of a receiving station to correct errors in the received data is called (FEC) and can increase on a data link when there is a lot of present. To enable this, a transmitting station must add extra data (called error correction bits ) to the transmission. However, the correction may not always represent a cost saving over that of simply resending the information. Hamming codes make FEC less expensive to implement through the use of a block parity mechanism.Computing involves counting the number of ones in a unit of data, and adding either a zero or a one (called a parity bit ) to make the count odd (for odd parity) or even (for even parity).
For example, 1001 is a 4-bit data unit containing two one bits; since that is an even number, a zero would be added to maintain even parity, or, if odd parity was being maintained, another one would be added. To calculate even parity, the operator is used; to calculate odd parity, the operator is used. Single bit errors are detected when the parity count indicates that the number of ones is incorrect, indicating that a data bit has been flipped by noise in the line. Hamming codes detect two bit errors by using more than one parity bit, each of which is computed on different combinations of bits in the data.
The number of parity bits required depends on the number of bits in the data transmission, and is calculated by the Hamming rule:pd + p + 1.