student id: 56159547
exam: 387850RR - Amplitude and Angle Modulation
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Questions 1 to 20: Select the best answer to each question. Note that a question and its answers may be split across a page
break, so be sure that you have seen the entire question and all the answers before choosing an answer.
1. Which of the following statements is true?
A. Direct FM isn't widely used.
B. In a direct FM transmitter, the oscillator frequency varies directly as a result of a modulation.
C. Modulation function of an indirect-FM transmitter is contained within the oscillator.
D. With an indirect-FM, the challenge is maintaining the frequency stability of the transmitter.
2. What factor determines the amount of carrier frequency deviation?
A. Intelligence frequency
B. Changing frequency
C. Intelligence amplitude
D. Frequency components
3. Determining the _______ is the first step in determining the occupied bandwidth of the modulated
carrier.
A. modulation index
B. frequency-modulated signal
C. side-frequency amplitudes
D. cyclical amplitude variations
4. Which of the following is a type of system often used in military communications?
A. Vestigial sideband
B. Amplitude modulation
C. ISB transmission
D. Pilot carrier
5. How many times greater is the peak amplitude of a full-carrier DSB AM at 100% modulation?
A. 2
B. 200
C. 4
D. 100
6. Two stations on a radio in a car are presenting a/an _______ signal when a receiver fluctuates back and
forth on a radio station.
A. constant
B. interference
C. suppression
D. variable
7. The component of an AM signal which varies as the intelligence signal varies in amplitude is the
A. frequency of the carrier.
B. frequency of the side bands.
C. amplitude of the carrier.
D. amplitude of the sidebands.
8. What would an observation of a side frequency require?
A. Frequency domain display
B. Lower-side frequency
C. Upper-side frequency
D. Carrier
9. Which of these involves combining an informational signal with a carrier?
A. Overmodulation
B. Linear device
C. Mixing
D. Modulation
10. What is the most important advantage of FM over AM?
A. PM signal can be made to look like FM.
B. FM has superior noise characteristics.
C. FM is completely insensitive to noise.
D. Phase modulation (PM) can be used to create FM indirectly.
11. Which of these will help to determine the bandwidth of a modulated signal?
A. Finding the side frequency
B. Determining how the power is distributed among the carrier and sidebands
C. Determining how the power is distributed among the frequency and deviations
D. Finding the amplitude
12. In AM transmission, which of these remain constant?
A. Amplitude and frequency
B. Frequency and sidebands
C. Sidebands and amplitude
D. Carrier power and amplitude
13. Which of these is an advantage to amplitude modulation?
A. It's used for two-way communication.
B. Modulation increases the total transmitted power because power developed in the sidebands adds to that of the carrier.
C. AM receivers respond to unwanted amplitude variations in exactly the same way they respond to desired ones.
D. The receiver is inherently susceptible to external electrical noise.
14. What's the index modulation with an intelligence voltage of 100 V and a carrier voltage of 25 V?
A. 25
B. 3
C. 75
D. 4
15. Which of the following statements is true?
A. FM is completely insensitive to noise.
B. Intelligence in AM is carried by frequency changes.
C. Intelligence in FM isn't carried by amplitude changes.
D. Static noise is common on FM.
16. _______ is used to predict the bandwidth necessary for an FM signal.
A. Bessel functions
B. Carson's rule
C. Ohm's law
D. Spectrum analysis
17. A PM signal be made to look like FM by
A. correcting for the deviation-increasing effect of higher intelligence frequencies.
B. increasing the frequency deviation.
C. modulating an oscillator directly.
D. placing a low-pass filter before the modulating stage.
18. Frequency and phase modulation are both forms of
A. angle modulation.
B. signal frequency.
C. deviation constant.
D. noise reduction.
19. An FM signal has an intelligence frequency of 100 Hz. What's the FM modulation index if the
frequency deviation is 300 Hz?
A. 300
B. 3
C. 100
D. 200
20. Phase modulation occurs when a modulating signal causes the instantaneous carrier phase rather than
its frequency to shift from its
A. reference value.
B. rotating phasor.
C. signal amplitude.
D. instantaneous frequency.
End of exam