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ECE Objective Questions { Analog Communication System }



57.  The output of a transmitter is 100 kW with carrier unmodulated and 132 kW when carrier is modulated by a sinusoidal wave; then depth of modulation is percent.
A.32
B.64
C.80
D.92

58.  If a 240-W carrier is simulataneously modulated by two sine waves with modulation indices of 0.3 and 0.4, its total modulation index is
A.0.5
B.0.7
C.0.12
D.0.75

59. In an amplitude-modulated wave-form, the amplitude of side bands is
A. independent of carrier amplitude
B. independent of modulation index
C. carrier amplitude x modulation index
D. ?2 x carrier amplitude x modulation index

60. In the spectrum of an FM wave
A. total number of sidebands depends on the value of modulation index
B. amplitude of any sideband depends on the value of modulation index
C. carrier frequency can disappear if modulation index is high
D. carrier frequency cannot disappear whatever the modulation index

61. When a signal with modulation index of m is passed through a frequency doubler, the output wave from the doubler will have a modulation index of
A. m
B. I11/2
C. 2m
D.4m

62. Modulated carrier power in FM
A. increases with modulating signal power
B. decreases with modulating signal power
C. is independent of modulating signal power
D.

63. For a PM signal, the modulating index depends upon
A. only the frequency of the modulating signal
B.onyl the amplitude of the modulating signal
C. both the amplitude and frequency of the modulating signal
D. the frequency of the carrier signal amongst other things

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