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

The advantages of specifying parameters during instantiation, The advantage...

The advantages of specifying parameters during instantiation method are: -  All values to all the parameters do not need to be specified. Only those parameters that are assigne

Explain SR latch using nor gates, Q. Explain SR Latch using NOR gates? ...

Q. Explain SR Latch using NOR gates? Let's inspect the latch more closely.   i. Suppose initially 1 is applied to S leaving R to 0 at this instance. The instant S=1 output o

Game playing techniques - artificial intelligence, Game Playing techniques ...

Game Playing techniques - artificial intelligence: Now we have dispensed with the essential background material for Artificial Intelligence problem solving techniques, and we m

Messagebox with the message, We have to make an application that will dynam...

We have to make an application that will dynamically add a menu strip with menu items to a form(ie NOT dragged and dropped onto the form) in Visual Basic. The menu strip should be

Computer data storage, Computer data storage: Computer data storage, f...

Computer data storage: Computer data storage, frequently called memory or storage refers to computer recording media and components, devices that received digital data used fo

Explain dial tone and ringing tone in strowger telephony, Explain Dial Tone...

Explain Dial Tone and Ringing Tone in strowger telephony. Dial Tone: it is used to indicate that the exchange is ready to recognize dialed digits by the subscriber. The subsc

Determine no.of processes to avoid race condition, To avoid race condition,...

To avoid race condition, the maximum number of processes that may be simultaneously inside the critical section is The maximum number of processes is one to ignore race conditi

What is a verification point?, A verification point is a point in a script ...

A verification point is a point in a script that you make to confirm the state of an object across builds of the application-under-test.

Corresponding port numbers, A) Around how many entries are there in this fi...

A) Around how many entries are there in this file on your VM? B) Select and list names and corresponding port numbers for four well-liked services listed in this file?

What are the roll and page areas, What are the roll and page areas? Ro...

What are the roll and page areas? Roll and page areas are SAP R/3 buffers used to kept user contexts (process requests).  The SAP dispatcher assigns procedure requests to work

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