ECE Modulation Q&A

1.____ is the maximum sideband suppression value using filter system?
(A) 50 dB
B.60 dB
C. 40 dB
D. 30 dB
2. ___ determine the number of sideband components in FM
A. Carrier frequency
B. Modulation frequency
(C) Modulation index
D. Deviation ratio
3. One of the following transmits only one sideband
(A) H3E
B. R3E
C.A3E
D. B8E
4. What produces the sidebands on FM?
A. Signal amplitude
B. Carrier harmonics
(C) Baseband frequency
D. Broadband frequency
5. Which test instrument displays the carrier and the sidebands amplitude with frequency to frequency?
A. Oscilloscope
(B) Spectrum analyzer
C. Frequency analyzer
D. Amplitude
6 Mixer is also known as a _____.
A. modulator
B. suppressor
(C) converter
D) beater
7. Which one of the following emission transmit the lower sideband and half of the upper sideband.
A. A5C
B. J3E
C. A3J
(D) A3H
8. An FM receiver signal _____.
A. vary in amplitude with modulation
(B) vary in frequency with modulation
C. vary in frequency and amplitude with wideband modulation
D. is not immune to noise
9. The process of impressing intelligence on the carrier is called
(A) modulation
B. defection
C. mixing
D. impression
10. ____ is an electronic instrument used to show both the carrier and the sidebands of a modulated signal in the frequency domain.
(A) Spectrum analyzer
B. Oscilloscope
C. Digital counter
D. Frequency counter
11. What part of the carrier is varied by the intelligence during modulation in an AM system?
A. Phase
B. Frequency
(C) Amplitude
D) Phase and amplitude
12. The difference between the RF carrier and the modulating signal frequencies is called the
A. USB
(B) LSB
C. Sideband
D. Carrier frequency
13. What stage in a radio transmitter isolates the oscillator from the load?
A. Oscillator
(B) Buffer
C. Separator
D. Mixer
14. The frequency of the unmodulated carrier in FM system is
A. modulating frequency
(B) center frequency
C. carrier frequency
D. deviation frequency
15. The radio of maximum deviation modulating frequency is called
A. carrier swing
(B) deviation ratio
C. modulation factor
D. modulation index
16. A carrier signal has
A. constant amplitude
(B) a frequency of 20 kHz and above
C. a varying amplitude
D. the information content
17. Which of the following is considered as an indirect method of generating FM?
A. Reactance modulator
B. Balance modulator
C. Varactor diode modulator
(D) Armstrong system
18. To generate an SSB or DSB signal one must use a circuit known as
A. Filter modulator
B. ring modulator
(C) balanced modulator
D. reactance modulator
19. Which is the first radio receiver?
A. TRF receiver
B. Superheterodyne receiver
(C) Crystal radio receiver
D. Heterodyne receiver
20. Single sideband reduced carrier emission type.
A. H3E
(B) R3E
C. J3E
D. B8E
21. Independent sideband emission type.
A. H3E
B. R3E
C. J3E
(D) B3E
22. Which one is not an advantage of SSB over AM?
A. Power saving
B. Requires haft the bandwidth
C. Wider area of reception
D. Better fidelity
23. The advantage of a low-modulated AM transmitter is
(A) less audio power required
B. better fidelity
C. higher value of operating power
D. less distortion
24. ____ is the bad effect caused by overmodulation in AM transmission
A. Increase in noise
B. Deviation in the operating frequency
(C) Interference to other radio services
D. Decrease in the output power
25. Which characteristic of a radio receiver refers to its ability to reject an unwanted signal signal?
A. Sensitivity
(B) Selectivity
C. Fidelity
D. Quality
26. AM transmission power increase with _____.
A. frequency
B. source
C. load
(D) Modulation
27. The modulation system inherently more resistant to noise
A. Single sideband suppressed carrier
(B) Frequency modulation
C. Pulse-position modulation
D. Amplitude shift keying
28. Subcarriers that are arranged so that the channels occupying adjacent frequency bands with some frequency space between them is known as
(A) guard bands
B AM bands
C. band gap
D. void band
29.Modulation of an RF carrier results in
A. multiple channels
B. smaller antennas
C. directional propagation
(D) all of the above
30. A process which occurs in the transmitter
A. Mixing
(B) Modulation
C. Heterodyning
D. Demodulation