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

Define polling, Define Polling. A Polling process is used to recognize...

Define Polling. A Polling process is used to recognize the highest priority source by software means. In this process there is one common branch address for all interrupts.

Define hyperlinks, Q. Define Hyperlinks? Hyperlinks, or links are one o...

Q. Define Hyperlinks? Hyperlinks, or links are one of the most significant characteristics of web pages. A link moves us from current page to a destination which is specified i

Describe arp message format in brief, Describe ARP message format in brief....

Describe ARP message format in brief.                             0                                        8                                      16

How will you allocate sub system, How will you allocate sub system? All...

How will you allocate sub system? Allocate every concurrent subsystem to hardware unit. General purpose processor or specialized functional unit as follows: Estimate per

Explain lexical substitution during macro expansion, Explain Lexical substi...

Explain Lexical substitution during macro expansion ? Lexical substitution is used to produce an assembly statement from a model statement. Model statements have 3 kinds of str

Explain the term- variables, Explain the term- Variables - Variables ar...

Explain the term- Variables - Variables are used for local storage of data -  Variables are usually not available to multiple processes and components. -  Variables would

Explain two dimensional array, Explain two dimensional array In two dim...

Explain two dimensional array In two dimensional arrays, array is a pointer-to-pointer-to-data type.: at the first level, it points to a block of pointers, one for each row. Th

What is pure virtual function, A class is made abstract by declaring one or...

A class is made abstract by declaring one or more of its virtual functions to be pure. A pure virtual function is one with an initializer of = 0 in its declaration

Common tasks to accomplish - artificial intelligence, Common Tasks to Accom...

Common Tasks to Accomplish: Once you've worried about what and why you're doing "AI", what has inspired you and how you're going to approach the job, then you just start to th

Time slice, The Linux Process Scheduler uses time slice to prevent a single...

The Linux Process Scheduler uses time slice to prevent a single process from using the CPU for too long. A time slice specifies how long the process can use the CPU. In our simulat

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