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 a zombie, What is a zombie? When a program forks and the child ...

What is a zombie? When a program forks and the child finishes before the parent, the kernel still keeps some of its information about the child in case the parent might require

Advantage of a numeric mailbox identifier, Does a numeric mailbox identifie...

Does a numeric mailbox identifier have any advantage over a mnemonic identifier? Explain. Several software systems permit the system administrator to select mailbox names, wher

Explain the main characteristics of semiconductor memory, Explain the Main ...

Explain the Main characteristics of semiconductor memory Memory, with regard to computers, most commonly signifies to semiconductor devices whose contents can be accessed (whic

What is the ccitt standard bandwidth for speech, The CCITT standard bandwid...

The CCITT standard bandwidth for speech is: (A) 20000 Hz                                  (B) 15000 Hz (C) 7000 Hz                                    (D) 3400 Hz Ans:

What do you meant by a storage device, Question : (a) What do you me...

Question : (a) What do you meant by a storage device? (b) List 5 examples of storage devices and give their uses (c) What are the differences between backup and ar

Define process, Define Process. Process: It is a program in executi...

Define Process. Process: It is a program in execution; process execution should progress into sequential fashion. Process contains: program counter stack dat

Explain the matlab language, This is a high-level matrix/array language wit...

This is a high-level matrix/array language with control flow statements, functions, data structures, input/output, and object-oriented programming features. It permits both "progra

What is assembler, Q. What is Assembler? An assembly program is used to...

Q. What is Assembler? An assembly program is used to transfer assembly language mnemonics to binary code for every instruction after the complete program has been written with

What is bus arbitration, Q. What is Bus arbitration? In this technique,...

Q. What is Bus arbitration? In this technique, I/O interface first needs to control bus and only after that it can request for an interrupt. In this technique because only one

Explain how the different access methods work, Question: (a) Primary an...

Question: (a) Primary and secondary memory differs in their way they access data: (i) Mention the four generic access methods usually present in a computer system. (ii) E

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