## Digital Communications Questions and Answers Part-6

1. Find the 32-ary waveform for the word ‘THINK’
a) 514172520
b) 202517415
c) 541172520
d) None of the mentioned

Explanation: “THINK”
ASCII value: T-001010; H-000100; I-100100; N-011100; K-110100
32-ary symbols(split into 5 bits): 5 1 4 17 25 20.

2. Find the 8-ary waveform for the word ‘HAPPY’
a) 4040020246
b) 0440020246
c) 6420200440
d) None of the mentioned

Explanation: “HAPPY”
ASCII value: H-000100; A-100000; P-000010; P-000010; Y-100110
8-ary symbols: 0 4 4 0 0 2 0 2 4 6.

3. Find the 32-ary waveform for the word ‘HAPPY’.
a) 280856
b) 658082
c) 288056
d) None of the mentioned

Explanation: “HAPPY”
ASCII value: H-000100; A-100000; P-000010; P-000010; Y-100110
32-ary symbols: 2 8 0 8 5 6.

4. What are the characteristics of an ideal transmission line?
a) Different amplitude
b) No distortion
c) Time delay
d) All of the mentioned

Explanation: The output from the ideal transmission line has some time delay different amplitude but it should not have distortion it should have the same shape as the input.

5. The ratio of the filter bandwidth at -60db and -6db amplitude response point is called as _____
a) Half point factor
b) Normalized factor
c) Shape factor
d) None of the mentioned

Explanation: Shape factor is a measure of how well realizable filter approximates to ideal filter. It is the ratio of filter bandwidths -60db and -6db amplitude points.

6. The point at which the output signal power has fallen to 0.707 of its peak value is called as _____
a) 3db point
b) Half power point
c) 3db & Half power point
d) None of the mentioned

Explanation: The frequency at which the output signal power falls to half the peak value is called as half power point or 3db point.

7. As the order of the filter increases, the cost ______ and complexity ______
a) Increases, increases
b) Increases, decreases
c) Decreases, increases
d) Decreases, decreases

Explanation: According to the design of the filter as the order increases the complexity and cost of the filter also increases.

8. Which filter has maximum flatness?
a) Chebyshev filter
b) Butter-worth filter
c) High pass filter
d) Normalized filter

Explanation: Butter-worth filter as the best approximation to ideal filter and has the maximum flatness in the filter pass-band.

9. The measure of the width of the main lobe is called as ________
a) Normalized bandwidth
b) Half power bandwidth
c) Null to null bandwidth
d) Absolute bandwidth