# Frequency, Phase Modulation, Modulation Index and Sidebands MCQ’s

This set of Avionics Multiple Choice Questions & Answers (MCQs) focuses on “Frequency, Phase Modulation, Modulation Index and Sidebands”.

1. The value of a change in frequency of the carrier wave by the modulating signal is called as?
a) Maximum modulation frequency
b) Maximum carrier frequency
c) Frequency deviation
d) Modulating frequency deviation

2. The maximum shift in frequency is 3kHz and the minimum and maximum deviation in frequency of the actual signal are 149.97MHz and 150.03MHz. What is the carrier frequency?
a) 150MHz
b) 153MHz
c) 140MHz
d) 100Mhz

3. What are FM and AM collectively referred together as?
a) Modulation
b) Angle modulation
c) Fast band modulation
d) Hi-fi Modulation

4. The frequency of modulating signal has no effect on the amount of frequency deviation of a carrier signal in FM.
a) True
b) False

5. FM and PM are more susceptible to noise than AM signals.
a) True
b) False

6. What is the ratio of frequency deviation to the modulating frequency is known as?
a) Frequency index
b) Modulating index
c) Modulation index
d) Modulation ratio

7. What type of modulation uses discrete values of carrier frequencies to transmit binary data?
a) Frequency modulation
b) Amplitude shift keying
c) Frequency shift keying
d) Phase modulation

8. Which of the following is false with respect to Pulse modulation?
a) Depends only on the frequency of the modulating signal
b) Phase of the carrier wave changes with respect to the modulating signal
c) Less affected by noise
d) Used to digitally transmit analog data

9. What is the modulation index of a system with modulating frequency 75kHz and maximum frequency deviation 15kHz?
a) 5
b) 7
c) 3
d) 1

10. What is it called when an FM signal occupies no more spectrum space than AM signal?
a) Amplitude modulated frequency wave
b) Narrowband FM
c) Shortband FM
d) Equalband FM

11. What is the number of significant sidebands produced when the bandwidth of the signal is 24kHz and the modulating frequency is 3kHz?
a) 4
b) 5
c) 6
d) 7

12. What is the deviation ratio if the maximum deviation is 25kHz and the maximum modulating frequency is 15kHz?
a) 1.55
b) 1.667
c) 4.7
d) 2.13

13. What is the modulation index for the FM to behave as a narrowband?
a) 1
b) 0.5
c) 0.25
d) 0.1

14. According to Carson’s rule, what is the bandwidth of the signal with a deviation of 30kHz and a maximum modulating signal of frequency 5kHz?
a) 70kHz
b) 90kHz
c) 100kHz
d) 80kHz 5 Star
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