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ECE Objective Questions { Analog Communication System }



85. The antenna current of an AM transmitter is 8 amperes when only the carrier is sent. It increases to 8.8 amperes when the carrier is sinusoidally modulated. The percentage modulation is
A.64%
B.72%
C.78%
D.84%

86. A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. The frequencies present in the output will be
A. 998 kHz and 1002 kHz
B. 998 kHz, 999.2 kHz, 1000.8 kHz, 1002.0 kHz
C. 998 kHz, 999.2 kHz, 999.7 kHz, 1000.3 kHz, 1000.8 kHz and 1002.0kHz
D. None of the above

87. A 360 W carrier is simultaneously modulated by two audio waves with modulation percentage of 55 and 65 respectively. The total side band power radiated will be
A. 180 W
B. 130 W
C. 60 W
D. 30 W

88. A radio transmitter, amplitude modulated radiates 50 kW of carrier power. The radiated power at 85% modulation will be
A. 50.85 kW
B.51.7 kW
C. 59.9 kW
D. 68.1 kW

89. The output current of a 60% modulated AM generator is 1.5 A. To what value will this current rise if the generator is modulated additionally by another audio wave whose modulation index is 0.7
A. 1.05 A
B. 1.15 A
C. 1.35A
D. 1.65 A

90. Now if the maximum depth of modulation is restricted to 70%, the new maximum side band power generated will be
A. 1.9 W
B.2.7 W
C. 5.5 W
D. 11.9 W

91. Which of the following will carry the same information as the AM wave itself?
A. VSB only
B. VSB and SSB
C.SSB,VSB and DSB
D. All of the above

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