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

What is model view controller (mvc), Model-View-Controller (MVC) is a desig...

Model-View-Controller (MVC) is a design pattern in which "the user input, the modelling of the external world and the visual feedback to the user are explicitly splitted and handle

Elucidate basic time division time switching method, With the help of block...

With the help of block diagram Elucidate basic time division time switching method. Basic Time Division Switching: Functional blocks of a memory based time division switching

Determine the decimal equivalent of hexadecimal number, The hexadecimal num...

The hexadecimal number for (95.5) 10 is ? Ans. (95.5) 10 = (5F.8) 16 Integer part Fractional part 0.5x16=8.0

Pebble merchant, There is a pebble merchant.He sells the pebbles,that are u...

There is a pebble merchant.He sells the pebbles,that are used for shining the floor.His main duty is to take length of the room''s sides. program 1 : package test.padovanstring

What is secondary list, What is secondary list? It permits you to enha...

What is secondary list? It permits you to enhance the information presented in the basic list.  The user can, for example, select a line of the basic list for which he require

How blocking and non blocking statements get executed, How blocking and non...

How blocking and non blocking statements get executed? Execution of blocking assignments can be viewed just like a one-step process: 1. Evaluate RHS (right-hand side equatio

Mini project, give proper code for any kind of project in oop c++

give proper code for any kind of project in oop c++

How many two-input AND and OR gates are required to realize , How many two-...

How many two-input AND and OR gates are required to realize Y=CD+EF+G ? Ans. Y=CD+EF+G No. of two i/p AND gates=2 No. of two i/p OR gates = 2 One OR gate to OR CD and EF

Major problems associated in writing with cache memories, Q. Major problems...

Q. Major problems associated in writing with cache memories? The data in main and cache memory can be written by processors or I/O devices. The major problems associated in wri

Two methods of copying a information document, There are basically two meth...

There are basically two methods of copying: Photocopying This is a modified development of photography. It is quite expensive and slow and is not often used for routine rep

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