Malayan Colleges Laguna  MITL ECE142 1)determines the number of sideband components in FM

Malayan Colleges Laguna  MITL ECE142

1)determines the number of sideband components in FM.

1. 1. Carrier frequency
   2. Modulation frequency
   3. Modulation index
   4. Deviation ratio

2. One of the following transmits only sideband.

1. H3E
2. R3E
3. A3E
4. B8E

3. What produces the sidebands on FM?

1. Signal amplitude
2. Carrier harmonics
3. Baseband frequency
4. Broadband frequency

4. Which test instrument displays the carrier and the sidebands amplitude with

frequency to frequency?

1. Oscilloscope
2. Spectrum analyzer
3. Frequency analyzer
4. Amplitude analyzer

5. Mixer is also known as                         .

1. modulator
2. suppressor
3. converter
4. beater

6. Which one of the following emission transmit the lower sideband and half of

the upper sideband.

1. A5C
2. J3E
3. A3J
4. A3H

7. An FM receive signal                          .

1. vary in amplitude with modulation
2. vary in frequency with modulation
3. vary in frequency and amplitude with wideband modulation
4. is not immune to noise

8. The process of impressing intelligence on the carrier is called

1. modulation
2. detection
3. mixing
4. impression

9.                  is an electronic instrument used to show both the carrier and the

sidebands of a modulated signal in the frequency domain.

1. Spectrum analyzer
2. Oscilloscope

3. Digital counter
4. Frequency counter

10. What part of the carrier is varied by the intelligence during modulation in an

AM system?

1. Phase
2. Frequency
3. Amplitude
4. Phase and amplitude

11. The difference between the RF carrier and the modulating signal frequencies is

called the

1. USB
2. LSB
3. Sideband
4. Carrier frequency

12. What stage in a radio transmitter isolates the oscillator from the load?

1. Oscillator
2. Buffer
3. Separator
4. Mixer

13. The frequency of the unmodulated carrier in FM system is

1. modulating frequency
2. center frequency
3. carrier frequency
4. deviation frequency

14. The ratio of maximum deviation to the maximum modulating frequency is called

1. carrier swing
2. deviation ratio
3. modulation factor
4. modulation index

15. A carrier signal has

1. constant amplitude
2. a frequency of 20 kHz and above
3. a varying amplitude
4. the information content

16. The modulated peak value of a signal is 125 V and the unmodulated carrier

value is 85 V. What is the modulation index? a. 0.47

b. 0.68

c. 0.32

d. 1.47

17. An 891 kHz carrier having an amplitude of 80 V is modulated by a 4.5 kHz audio

signal having an amplitude of 45 V.. The modulation factor is a. 0.56

b. 0.65

c. 1.78

d. 1.25

18. What is the modulation index of an FM signal having a carrier swing of 75 kHz when the modulating signal has frequency of 3 kHz?

a. 25

b. 12.5

c. 0.04

d. 0.08

19. In a FM system, if modulation index is doubled by halving the modulating

frequency, what will be the effect on the maximum deviation?

1. No effect
2. Maximum deviation doubles
3. Decreases by 1/2
4. Increases by 1/4

20. Which of the following is considered as an indirect method of generating FM?

1. Reactance modulator
2. Balanced modulator
3. Varactor diode modulator
4. Armstrong system

21. To generate an SSB or DSB signal one must use a circuit known as

1. filter modulator
2. ring modulator
3. balanced modulator
4. reactance modulator

22. Which is the first radio receiver?

1. TRF receiver
2. Superheterodyne receiver
3. Crystal radio receiver
4. Heterodyne receiver

23. An interfering signal with a frequency equal to the received signal plus twice

the IF is called

1. image frequency
2. center frequency
3. rest frequency
4. interference frequency

24. Double sideband full carrier emission type.

1. A3J
2. H3E
3. R3A
4. A3E

25. Single sideband reduced carrier emission type.

1. H3E
2. R3E
3. J3E
4. B8E

26. A single sideband suppressed carrier emission type.

1. H3E
2. R3E
3. J3E
4. B8E

27. Independent sideband emission type.

1. H3E
2. R3E
3. J3E
4. B8E

28. Vestigial sideband emission type

1. C3F
2. J3E
3. R3E
4. B8E

29. Single sideband full carrier emission type.

1. R3E
2. H3E
3. J3E
4. B8E

30. Phase modulation emission type.

1. F3E
2. F3C
3. F3F
4. G3E

31. Which one is not an advantage of SSB over AM?

1. Power saving
2. Requires half the bandwidth
3. Wider area of reception
4. Better fidelity

32. The advantage of a high level modulated AM transmitter is

1. less audio power required
2. better fidelity
3. higher value of operating power
4. less distortion

33. The advantage of a lowlevel modulated AM transmitter is

1. less audio power required
2. better fidelity
3. higher value of operating power
4. less distortion

34.                is the bad effect caused by overmodulation in AM transmission.

1. Increase in noise
2. Deviation in the operating frequency
3. Interference to other radio services
4. Decrease in the output power

35. Which characteristic of a radio receiver refers to its ability to reject an

unwanted signal?

1. Sensitivity
2. Selectivity
3. Fidelity
4. Quality

36. What type of emission is frequency modulation?

1. F3E
2. G3E
3. A3E
4. B3E

37. AM transmission power increases with                     .

1. frequency
2. source
3. load
4. modulation

38.              locks the FM receiver to a stronger signal.

1. Hall effect
2. Capture effect
3. Image frequency
4. Homing

39. What is the highest percentage of modulation for AM? a. 50 %

b. 75 %

c. 100 %

d. 80 %

40. In FM, the Carson's Rule states that the bandwidth is equal to twice the sum

of the modulating frequency and                         .

1. carrier signal
2. modulating index
3. frequency deviation
4. image frequency

41. What is the carrier swing of an FM transmitter when modulated by 75 %?

1. 53.2 kHz
2. 48 kHz
3. 56.25 kHz
4. 112.5 kHz

42. The modulation system inherently more resistant to noise.

1. Single sideband suppressed carrier
2. Frequency modulation
3. Pulseposition modulation
4. Amplitude shift keying

43. Subcarriers that are arranged so that the channels occupying adjacent

frequency bands with some frequency space between them is known as

1. guard bands
2. AM bands
3. band gap
4. void band

44. Modulation of an RF carrier results in

1. multiple channels
2. smaller antennas
3. directional propagation

4. all of the above

44. A process which occurs in the transmitter.

1. Mixing
2. Modulation
3. Heterodyning
4. Demodulation

45. A process which occurs in the receiver.

1. Beating
2. Modulation
3. Mixing
4. Demodulation

46. One part of the transmitter that protects the crystal oscillator from

"pulling".

1. Buffer amplifier
2. Modulator
3. Power amplifier
4. Antenna coupler

47. What aspect of the carrier is changed by modulation?

1. Frequency
2. Phase
3. Amplitude
4. Depends on the type of modulation

48. The amplitude of a sine wave which is modulated by a musical program will

1. be complex
2. contain fundamental frequencies
3. contain harmonic frequencies
4. all of the above

49. What will be the result of the gain level being too high for signals entering

the modulator?

1. Receiver noise
2. Excessive volume of receiver output
3. Oscillator disturbance
4. Distortion and splatter

50. Amplitude modulation causes the amount of transmitter power to

1. increase
2. decrease
3. remain the same
4. double

51. When a carrier is modulated 100%, the total power increases by what percentage

over that of the carrier alone? a. 25 %

b. 50 %

c. 75 %

d. 100 %

52. When the amplitude of the modulating voltage is increased for AM, the antenna

current will

1. increase
2. decrease
3. remain constant
4. decrease exponentially

53. An increase in transmitter power from 25 W to 30 W will cause the antenna

current to increase from 700 mA to

1. 800 mA
2. 750 mA
3. 767 mA
4. 840 mA

54. A second modulating tone having the same amplitude but a different frequency

is added to the first at the input to the modulator. The modulation index will be increased by a factor of

1. square root of 3
2. square root of 2
3. 2
4. 3

55. A 1000 kHz carrier is modulated by a 2500 Hz tone. One frequency component of

the modulated signal is

1. 1200 Hz
2. 5000 Hz

c. 1002.5 kHz

d. 2500 Hz

56. A 1200 kHz carrier is amplitudemodulated by two tones of 500 Hz and 700 Hz.

Which one is a frequency component of the modulated wave?

a. 1195 kHz

b. 1199.3 kHz

c. 1199.7 kHz

d. 1205 kHz

57. Identify a modulation method, or methods in use for a commonemitter

configuration.

1. Base modulation
2. Emitter modulation
3. Collector modulation
4. Both A and C

58. The RF signal injected into a balanced modulator is 10 MHz and the modulating

frequency is 1 kHz. Which frequency, or frequencies, will not appear in the output?

1. 9.999 MHz
2. 10 MHz

c. 10.0001 MHz

d. both A and B

59. Unwanted sidebands in SSB equipment can be suppressed by one or more of the

following methods.

1. Phasing method
2. Filter method
3. Decoder method
4. Both A and B

60. Envelope detection is concerned with the process of

1. mixing
2. heterodyning
3. modulation
4. rectification

61. Diagonal clipping in envelope detection will result in

1. distortion
2. phase reversal
3. reduced sensitivity
4. amplitude damage

62. Product detection requires the process of

1. rectification
2. heterodyning
3. decoding
4. phase shifting

63. A sine wave which is coherent with carrier has identical

1. amplitude
2. frequency
3. phase angle
4. both B and C

64. Frequency modulation and phase modulation are collectively referred to as

1. stereo
2. angle modulation
3. high fidelity modulation
4. FCC modulation

65. In FM the change in carrier frequency is proportional to what attribute of the

modulating signal?

1. angle
2. frequency
3. amplitude
4. tone

66. A louder sound, when generating the modulating waveform for FM, will cause a

greater

1. carrier amplitude
2. angle amplitude
3. distortion at the receiver
4. frequency deviation

67. If a positive change in modulation signal level of 200 mV will cause a

positive frequency deviation of 10 kHz, what will be the frequency deviation for a negative change of 100 mV in the level of the modulating signals?

1. 0
2. 5 kHz

c. +5 kHz

d. +0 kHz

68. A particular 15 kHz modulation tone results in a peak frequency deviation of

75 kHz. What is the modulation index?

1. 5
2. 15

3. 75
4. 3

69. A 15 kHz sine wave frequencymodulates an 88 MHz carrier. A sideband frequency

will be found at a. 87.970 MHz

b. 87.985 MHz

c. 88.015 MHz

d. All of these

70. A device whose capacitance is deliberately made to be a function of the

applied voltage.

1. Varactor diode
2. UJT
3. SAW
4. Variable capacitor

71. A reactance modulator is one method of obtaining

1. indirect FM
2. direct FM
3. demodulation
4. low frequency filtering

72. A device, now available in IC form, is useful for direct FM and as one element

in the phaselocked loop.

1. AFC
2. AGC
3. VCO
4. LPF

73.              is a frequency change process, whereby the phase deviation and

frequency deviation are multiplied by some fixed constant.

1. Translation
2. Multiplication
3. Division
4. Addition

74. A circuit that has the function of demodulating the frequencymodulated

signal.

1. AFC
2. Envelope detector
3. Decoder
4. FosterSeeley discriminator

75. The ratio detector is superior to the slope detector because

1. it is less sensitive to phase modulation
2. it is less sensitive to noise spikes
3. it is less sensitive to interference causing AM
4. Both B and C

76. One implementation of a pulseaveraging discriminator is

1. a freerunning multivibrator
2. a crystalcontrolled oscillator
3. a quartz crystal filter
4. a triggered multivibrator