DOUBT

Question

Answer 1

Let us calculate the calculated Hamming code as follows :

p1  p2  0  p4    0    0    1..

So we calculate the even parity as :

For p1 : Bit positions 1 , 3 , 5 and 7 to be considered ..

So p1 = 1 as bits are 0 , 0 and 1 are there at 3rd , 5th and 7th positions respectively..

For p2 : Bit positions 2 , 3 , 6 and 7 to be considered..

So p2 = 1 as well..

For p3 : Bit positions 4 , 5 , 6 and 7 to be considered 

So p4 = 1 as well..

So we can see there is mismatch at p1 and p2..

So wrong bit position is found as : 1 + 2  = 3

So bit at 3 = 1 instead of 0..

Hence correct message (4 bits ) =  1 0 0 1 

                                               =   9

Hence 9 (option A) is the correct answer..

 

Comments

that is P4 , and its already given 1 for P4

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from where u got p4 ? it is 7 bit hamming code we will get parity bit only upto p3

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P1 = 2^0   [here  P1 means first bit]  
P2= 2^1
P4= 2^2 [ 3rd parity bit , but position is 4th ]
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and so on