Test Bank for Electronic Communications A System Approach 1st Edition Beasley

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,Electronic Communications A System Approach 1st Edition Beasley Test Bank




Beasley/Electronic Communications

Chapter 2: Amplitude Modulation

Multiple Choice Questions

1. What law is represented when current flow through a device increases in direct
proportion to voltage?

A. Hartley’s law
B. Plank’s law
C. Ohm’s law
D. Henry’s law

2. What situation occurs if the modulating signal amplitude continues to increase?

A. Maximum amplitude
B. Overmodulation
C. Sideband splatter
D. Odd harmonics

3. A transmitter modulator circuit combines carrier and intelligence signals that are widely
separated in _____________.

A. frequency
B. amplitude
C. harmonics
D. voltage

4. Which of the following is the most important advantage of SSB systems?

A. Reducing the noise present at receiver by half.
B. All information is contained within varying-amplitude sidebands.
C. More effective utilization of the available frequency spectrum.
D. The carrier amplitude and frequency always remain constant.

5. Which of the following is the term that defines when two signals at different
frequencies are combined in a nonlinear device?

A. Aliasing
B. Mixing
C. Foldover distortion
D. Fluctuating

6. A phasor rotating at a constant rate will generate a(n)____________.



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, A. sine wave
B. angular velocity
C. waveform
D. amplitude

7. In an AM transmission, why does the carrier contain no information?

A. It is always changing.
B. It is related to sine-wave frequency.
C. It never changes.
D. The signal is a low frequency compared to the carrier.

8. Mixing (modulation) is achieved when signals are applied to a(n) ____________.

A. nonlinear device
B. sideband
C. linear device
D. intermod

9. The ___________ produces side frequencies or sidebands, one on each side of the
carrier.

A. phasors’ angular velocity
B. vector sum
C. pure sine wave
D. modulated AM signal

10. The rate of phasor rotation is called angular _____________.

A. velocity
B. sidebands
C. sine waves
D. frequencies

11. Which of the following is an example of an application where double-sideband, full-
carrier (DSBFC) AM would be used?

A. Marine and citizens band (CB) radios
B. Military services
C. Aircraft-to-tower communication
D. Amateur (ham) radios

12. What is the carrier’s job in the modulator?

A. Calculation of the modulation index
B. Frequency translation

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, C. Aliasing
D. Transmitting

13. What was ultimately developed in the search for a communications technique that was
immune to noise?

A. FM
B. AM transmitter
C. Bandwidth
D. Frequency spectrum

14. All information contained at the output of the AM modulator is contained within the
__________.

A. balanced modulators
B. bandwidth
C. transmitter
D. sidebands

15. Why are SSB receivers more difficult to tune than conventional AM receivers?

A. Need for carrier reinsertion
B. Bandwidth required by SSB cut in half
C. Complete signal cancellation may result
D. Overcrowded high-frequency spectrum

16. What type of sideband is used for analog television video transmissions?

A. Amplitude-compandored
B. Vestigial
C. ISB transmission
D. Pilot carrier

17. Which of the following would be a reason why double-sideband AM is still so widely
used?

A. SSB systems more complex
B. Power-savings
C. Noise advantages
D. Effective utilization of available frequency spectrum

18. Conventional AM transmitters are rated in terms of _________________.

A. bandwidth
B. amplitude modulating signals
C. modulated waveforms

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