# Cyclic and Linear Block Codes

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**