Explain about hamming error correcting code, Computer Engineering

Assignment Help:

Q. Explain about Hamming error correcting code?

Richard Hamming at Bell Laboratories worked out this code. We will only introduce this code with help of an illustration for 4 bit data. Let's presume a 4 bit number b4, b3, b2, b1.  In order to create a simple error detection code which detects error in one bit only we can just add an odd parity bit.  Though if we want to find which bit is in error then we may have to employ parity bits for different combinations of these 4 bits in such a way that a bit error can be recognized uniquely.  For illustration we can create four parity sets as below

Source Parity                            Destination Parity

b1, b2, b3                                                        P1                                            D1

b2, b3, b4                                                        P2                                            D2

b3, b4, b1                                                        P3                                            D3

b1, b2, b3, b4                                                  P4                                            D4

Now very interesting phenomenon can be noticed in above displayed parity pairs.  Assume data bit b1 is in error on transmission then it will cause alteration in destination parity D1, D3, D4.

ERROR IN                                                     Cause change in Destination Parity 

(One bit only)

b1                                                                                             D1, D3, D4

b2                                                                                             D1, D2, D4

b3                                                                                             D1, D2, D3, D4

b4                                                                                             D2, D3, D4

Figure: The error detection parity code mismatch

So by simply comparing parity bits of source and destination we can recognize that which of four bits is in error. This bit then can be complemented to eliminate error. Please note that even source parity bit can be in error on transmission but under assumption that just one bit (irrespective of data or parity) is in error it would be detected as just one destination parity would be different. What should be length of error detection code that detects error in one bit? Before responding this question we have to look in comparison logic of error detection. Error detection is done by comparing two ‘i’ bit error detection and correction codes fed to comparison logic bit by bit (see figure below). Let’s have comparison logic that produces a zero if compared bits are same or else it generates a one. Consequently if similar Position bits are similar then we obtained zero at that bit Position however if they are dissimilar that is this bit position may point to an error then this Particular bit position would be marked as one. This way a matching word is built. This matching word is ‘i’ bit long so can signify 2i values or combinations.


Related Discussions:- Explain about hamming error correcting code

Explain the disadvantages off-the-shelf, Explain the disadvantages Off-the...

Explain the disadvantages Off-the-shelf -  can be over-complex since it tries to cover as many characteristics as possible (for example most users of Word only utilise about

EDC, Conparision of masfet and jfet

Conparision of masfet and jfet

Which is not a layer of input-output management module, Which is not a laye...

Which is not a layer of IO management module? Ans. MCS that is Management Control System, is not a layer of IO management module.

What is shift operation, Q. What is Shift operation? Shift: Shift ope...

Q. What is Shift operation? Shift: Shift operation is employed for transfer of bits either to left or to right. It can be used to comprehend simple arithmetic operation or da

Iterative deepening search, Iterative Deepening Search: So, breadth fi...

Iterative Deepening Search: So, breadth first search is always guaranteed to find a solution (if one exists), actually it eats all the memory. For the depth first search, ther

What do you mean by linker, Q. What do you mean by Linker? For modular...

Q. What do you mean by Linker? For modularity of your programs it is better to break your program in numerous sub routines. It's even better to put common routine such as read

Write a short notes on storage classes in c, Write a short notes on storage...

Write a short notes on storage classes in C. Every variable and function in C has two attributes : type and storage class. The four storage classes are automatic, external, reg

Different search strategies- artificial intelligence, Different search stra...

Different search strategies- artificial intelligence: To help us think about the different search strategies, we use two analogies. Firstly, we suppose that the professor keep

Array user interface, You were offered bonus marks for separating the user ...

You were offered bonus marks for separating the user interface code from the main logic of your program. This design choice makes it very easy to replace the user interface without

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd