# Waveform Coding

This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Waveform Coding”.

1. Channel coding relates to area such as
a) Waveform coding
b) Structured sequence
c) Waveform coding & Structured sequence
d) None of the mentioned

2. Examples of structured sequences are
a) Block codes
b) Convolutional codes
c) Turbo codes
d) All of the mentioned

3. Antipodal signals are
a) Mirror images
b) 1800 apart
c) One is negative of the other
d) All of the mentioned

4. Orthogonal vectors are
a) Perpendicular to each other
b) Their dot product must be zero
c) One signal cannot interfere with the other
d) All of the mentioned

5. In orthogonal signalling as k increase there is
a) Improved error performance
c) Improved bandwidth
d) None of the mentioned

6. In non orthogonal signalling as k increases there is
b) Improved bandwidth efficiency
c) Increase in required Eb/N0
d) All of the mentioned

7. In orthogonal signal, all cross correlation coefficients are
a) One
b) Zero
c) Negative
d) None of the mentioned

8. The smaller the cross correlation, the ______ is the distance between the signal vectors.
a) More
b) Less
c) Double
d) Half

9. Hadamard matrix is given as
a)

```H2 =  H1 H1
H1 H1```

b)

```H2 =  H1 H1
H1'H1```

c)

```H2 =  H1 H1
H1 H1'```

d)

```H2 =  H1'H1
H1 H1```

10. Biorthogonal set consists of
a) Orthogonal signals
b) Antipodal signals
c) Combination of orthogonal and antipodal
d) None of the mentioned

11. Which codes perform better?
a) Orthogonal
b) Biorthogonal
c) Orthogonal & Biorthogonal
d) None of the mentioned

12. Biorthogonal codes needs ________ bandwidth as orthogonal codes.
a) Equal
b) Double
c) Half
d) Triple

13. Transorthogonal code is obtained by
a) Deleting last digit of each orthogonal codeword
b) Deleting first digit of each orthogonal codeword
c) Doubling each digit of orthogonal codeword
d) Taking negative of each digit of orthogonal codeword

14. Which code requires minimum Eb/N0?
a) Orthogonal
b) Biorthogonal
c) Simplex
d) All of the mentioned