GATE1987-2-i

Question

Match the pairs in the following questions:
$$\begin{array}{|l|l|l|} \hline \text {(A) Cyclic Redundancy Code} & \text {(p) Error Correction} \\\hline \text {(B) Serial Communication} &  \text{(q) Wired-OR } \\\hline \text{(C) Open Collector} & \text{(r) Error detection} \\\hline \text{(D) Hamming Code} &  \text{(s) RS-232-C} \\\hline \end{array}$$

Answer 1

$$\begin{array}{|l|l|l|} \hline \text {(A) Cyclic Redundancy Code} & \text {(r) Redundancy checking technique}\\&\quad\text{(error detection)} \\\hline \text {(B) Serial Communication} &  \text{(s) RS-232-C } \\\hline \text{(C) Open Collector} & \text{(q) Wired OR} \\\hline \text{(D) Hamming Code} &  \text{(p) Error Correction Method} \\\hline \end{array}$$

Explanation:

• A. A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data
• B. RS-232C is the physical interface that your computer uses to talk to and exchange data with your modem and other serial devices
• C. Reference http://www.ni.com/white-paper/3544/en/
• D. The Hamming code is an error correction method using redundant bits. By rearranging the order of bit transmission of the data units, the Hamming code can correct single bit errors.

Comments

the Hamming code can correct burst errors.

It can correct only single-bit error. Burst error means 2 or more data bits have been corrupted or flipped from 0 to 1 or 1 to 0.

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@ankitgupta.1729 hamming code can even correct more than one bit errors . 
For example if the minimum hamming distance is 5 then it can correct 

t is the number of bit errors that can be corrected. 

2*t + 1 <=5  i,e  t<=2 . It means that we can correct upto 2 bit errors and detect upto 4 bit errors. 

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can you give an example where the received codeword is wrong at two or more bit positions and hamming code is able to correct it ?