Analog Communications Questions and Answers – Threshold Effect in FM

This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Threshold Effect in FM”.

1. Which statement is true about thermal noise power?
a) it is proportional to B
b) it is proportional to √B
c) it is proportional to B2
d) it is proportional to √B2

Explanation: Thermal noise is effectively white noise. It extends over a wide range spectrum. Its noise power is proportional to the bandwidth (B).

2. Cosmic noise is caused by ________
a) Distant stars
b) Lightning discharge
c) Solar eruptions
d) Disturbances in the atmosphere

Explanation: Cosmic noise a random noise that originates from outside the earth’s atmosphere. It can be detected and heard on radio receivers.

3. Which of the following filter is used only at higher frequencies?
b) Crystal Gate
c) Half Lattice
d) Full Lattice

Explanation: It is the ladder filter which is used only at higher frequencies.

4. Sampling theorem finds application in ________
a) FM
b) PCM
c) AM
d) PM

Explanation: Sampling theorem can be seen as a fundamental bridge between continuous time signals and discrete time signals. It finds its application in Pulse Code Modulation (PCM).

5. The channel capacity is exactly equal to which of the following?
a) Bandwidth
b) Noise rate
c) Amount of information per second
d) Entropy

Explanation: The channel capacity of a communication system is exactly equal to the amount of information per second.
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6. The ionosphere consists of __________ layer.
a) negative charge
b) positive charge
c) no charge
d) neutral

Explanation: The ionosphere is the ionized part of Earth’s upper atmosphere. It consists of a negative layer.

7. The noise performance of a square law demodulator of AM signal is ___________
a) Identical with that of a synchronous detector
b) Better than that of an envelope detector
c) Better than that of a synchronous detector
d) Poorer than that of an envelope detector

Explanation: The noise performance of a square law demodulator of AM signal is better than that of a synchronous detector.

8. Which system is free from noise?
a) FM
b) AM
c) PCM
d) PM

Explanation: Noise is the unwanted signal or disturbances in a communication system. It is a frequency modulated system which remains free from noise.

Sanfoundry Global Education & Learning Series – Analog Communications.