hamming

Question

In hamming method to transmit a message of size 12B data . How many minimum number of padding bits are considered to correct single bit error

Comments

7 ??

Answer 1

Using Hamming code , we can correct the errors .. For that we need to add some bits in between the bits of the message at specified locations , which are known as padding bits . These bits are placed at places which are powers of 2..i.e. at position number 1 , 2 , 4 etc starting from left i.e. from MSB (most significant bit)..

Now to know how many padding bits needed we have the following equation :

2^r   >=  m + r + 1

The simple reason behind this equation is that we have to keep rth padding bit which is the last padding bit at 2^r position..

Hence here message size given    =     12 B      =     96 bits

Hence  m  =   96 bits

Thus we have :

          2^r   >=  96 + r + 1

==>    2^r  >=   97 + r

==>    r_min    =    7     

Hence number of padding bits  =  7

Comments

Formula is 2^p >= m+p+1  Condition is not correct. PLZ correct it .

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@habib 

here they have asked..in order to correct single bit error....

if question was to correct multiple errors also...will it affect usage of that formula?

and any difference between correcting single bit error and detecting single bit error?

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hamming code is error correcting code ryt. it can correct single bit error.

This not work for multiple bit error.

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Here we are asked about padding bits that are to be added to the data which is an entirely different question. Wht u r talking about is related to the minimum Hamming distance ..Regarding that we have:

a) To correct 'd' errors , minimum Hamming distance  = 2d + 1

b) To detect 'd' erros , minimum Hamming distance  =  d + 1

But here we are talking about Hamming code uasge instead..It is not to be confused with Hamming distance..:) 

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yeah got confused.. thanks :) @habib