GO Classes Test Series 2024 | Mock GATE | Test 12 | Question: 10

Answer 1

1. We can't detect all the errors with single CRC False

2. HD is 1 True

3.Purpose of parity bit is to detect single errors. So if any one bit from the data changes the parity bit  will change too. So in total 2 bits have changed. So  the min HD is 2

True

4. To detect d+1 and to correct 2d+1. Clearly we need more to correct.False

Comments

Option C explanation:

Suppose that for a message, we are adding a single parity bit.

Ex: message : 1101. if we go by evenparity then the parity bit that will be added is 1.

now,code word: 11011.

suppose we flip 2^nd bit in the code word (1 → 0). so, to maintain even parity the parity bit will also change from (1 → 0).

new code word : 10010

hamming distance between initial code word and new code word is 2.

Hence, the minimum hamming distance possible is 2.

 

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but can you plz tell why you are changing the codeword ?

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To find hamming distance we need 2 code words. From my example, we already have a code word which is 11011. For the second code words, you are free to choose any code word and find hamming distance, but inorder to get a minmum hamming distance, im choosing the other code word with just 1 bit change in the message word.