M-ary Modulation

Digital Communications Systems

This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “M-ary modulation and amplifiers”.

1. In M-ary FSK, as M increases error
a) Increases
b) Decreases
c) Does not get effected
d) Cannot be determined

2. In M-ary FSK as M tends to infinity, probability of error tends to
a) Infinity
b) Unity
c) Zero
d) None of the mentioned

3. For non coherent reception of PSK _____ is used.
a) Differential encoding
b) Decoding
c) Differential encoding & Decoding
d) None of the mentioned

4. Which modulation technique have the same bit and symbol error probability?
a) BPSK
b) DPSK
c) OOK
d) All of the mentioned

5. An amplifier uses ______ to take input signal.
a) DC power
b) AC power
c) DC & AC power
d) None of the mentioned

6. Which has 50% maximum power efficiency?
a) Class A
b) Class B
c) Class AB
d) None of the mentioned

7. Which generates high distortion?
a) Class A
b) Class B
c) Class C
d) Class AB

8. Class B linear amplifiers have maximum power efficiency of
a) 50%
b) 75%
c) 78.5%
d) None of the mentioned

9. Which has the maximum power efficiency?
a) Class A
b) Class B
c) Class C
d) Class AB

10. Free space in idealization which consists
a) Transmitter
b) Receiver
c) Transmitter & Receiver
d) None of the mentioned

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