This set of Digital Communication Multiple Choice Questions & Answers focuses on “Properties of Convolution Codes and Reed-Solomon Codes”.

1. Which distance is related to the error correcting capability of the code?

a) Maximum distance**b) Minimum distance**

c) Maximum & Minimum distance

d) None of the mentioned

2. A catastrophic error is an event whereby ______ number of code symbol error causes _______ number of decoded data error bits.

a) Finite, finite**b) Finite, infinite**

c) Infinite, finite

d) Infinite, infinite

3. A code should be selected such that it should**a) Not have catastrophic error propagation**

b) Have minimum free distance

c) All of the mentioned

d) None of the mentioned

4. The error correcting capability of a code scheme increases as the

a) Number of channel symbols per information bit increases

b) Bandwidth increases

c) Information per bit increases**d) All of the mentioned**

5. Which has a limited resolution?

a) Hard decision decoder**b) Soft decision decoder**

c) Hard & Soft decision decoder

d) None of the mentioned

6. Which parameter is used in soft decision algorithm?

a) Euclidean distance

b) Euclidean distance squared**c) Euclidean distance & distance squared**

d) None of the mentioned

7. Which factor is desirable?

a) Minimum correlation**b) Maximum correlation**

c) Maximum distance

d) None of the mentioned

8. Soft decision results in**a) Increase in complexity**

b) Decrease in storage

c) Increase in complexity & Decrease in storage

d) None of the mentioned

9. A feedback decoder makes hard decision.**a) True**

b) False

10. The look ahead length L is given by**a) m+1**

b) m-1

c) (m+1)/2

d) 1-m

11. On increasing L

a) Coding gain increases

b) Complexity increases**c) Coding gain & Complexity increases**

d) None of the mentioned

12. Reed Solomon codes are

a) Non binary

b) Cyclic**c) Non binary & Cyclic**

d) None of the mentioned

13. The minimum distance for Reed Solomon code is given by

a) n+k+1**b) n-k+1**

c) 1-n-k

d) 1+n-k

14. R-S codes have

a) High code rate

b) Low redundancy**c) High code rate & Low redundancy**

d) None of the mentioned

15. Greater the redundancy greater will be the error correcting capability.**a) True**

b) False

16. A primitive element are those which yield ______ when raised to higher order exponents.

a) All zero elements**b) Non zero elements**

c) Unity elements

d) None of the mentioned

17. If the inversion was performed correctly, then the multiplication of the original matrix with the inverted matrix should yield identity matrix. This is known as

a) Identity theorem**b) Safety theorem**

c) Multiplication theorem

d) Inversion theorem