Cyclic and Linear Block Codes

Digital Communications Systems

This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Cyclic codes and linear block codes”.

1. The cyclic codes are designed using
a) Shift registers with feedback
b) Shift registers without feedback
c) Flipflops
d) None of the mentioned

2. A cyclic code can be generated using
a) Generator polynomial
b) Generator matrix
c) Generator polynomial & matrix
d) None of the mentioned

3. The feedback shift register circuit is called as
a) Multiplying circuit
b) Dividing circuit
c) Feedback circuit
d) Shifting circuit

4. In the dividing circuit, the parity polynomial is obtained by the
a) Quotient
b) Remainder
c) Dividend
d) Divisor

5. The received code contains an error if the syndrome vector is
a) Zero
b) Non zero
c) Infinity
d) None of the mentioned

6. Block codes are generated using
a) Generator polynomial
b) Generator matrix
c) Generator polynomial & matrix
d) None of the mentioned

7. Extended go-lay code is formed by
a) Adding overall parity bit to perfect go-lay code
b) Ex-oaring overall parity bit with perfect go-lay code
c) Ex-oaring each bit of go-lay code
d) Dividing the overall parity bit with perfect go-lay code

8. Block length is the _____________ in the code word.
a) Number of elements
b) Distance between elements
c) Number of parity bits
d) None of the mentioned

9. The rate of a block code is the ration of
a) Block length to message length
b) Message length to block length
c) Message weight to block length
d) None of the mentioned

10. Linear codes are used for
a) Forward error correction
b) Backward error correction
c) Forward error detection
d) Backward error detection

11. The k-bit message forms ____ distinct messages which is referred to as k-tuples.
a) 2k
b) K2
c) 2k
d) 21/k

12. The sum of any two vectors in subset S is also in S. This is called as
a) Addition property
b) Subset property
c) Closure property
d) Similarity property

13. To avoid corruption during transmission, the code-word should be
a) Near
b) Far apart
c) Far
d) None of the mentioned

14. In a standard matrix set code-word there are _______ cosset.
a) 2k
b) 2n+k
c) 2n-k
d) 2n

15. Syndrome is calculated by
a) HT/r
b) rHT
c) rH
d) None of the mentioned

16. The _____ of the code-word is the number of non zero elements.
a) Size
b) Weight
c) Distance
d) Subspace

17. Some examples of linear codes
a) Hamming code
b) Reed-Solomon code
c) Parity code
d) All of the mentioned

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