Question

Which of the following statements is true about error detection techniques used on communications link?

• A. Cyclic Redundancy Check (CRC) sequence can detect as well as correct errors
• B. Error detection alone cannot be used on simplex links
• C. (7, 4) Hamming code can detect up to 3-bit errors
• D. All of the above

Hint:

Different error detection methods have specific capabilities and are used in different conditions.

Answer 1

The Correct Option is D

(a) Cyclic Redundancy Check (CRC) sequence can detect as well as correct errors: CRC sequences are designed to detect various errors in the data. However they do not correct errors. Therefore the statement is incorrect. 
(b) Error detection alone cannot be used on simplex links: In simplex communication, data is sent in one direction only, which means that error detection alone is sufficient as no feedback mechanism is available to correct the errors. 
(c) (7, 4) Hamming code can detect up to 3-bit errors: A (7,4) hamming code is capable of correcting a single bit error, but it can only detect up to two-bit errors. Therefore this is also an incorrect statement.