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ECE Objective Questions { Analog Communication System }



92. A balanced modulator produces
A. AM
B.SSB
C.DSB
D.VSB

93. The modulation index of a AM is to be measured using an oscilloscope. In this arrangement
A. modulated signal and modulating signal both are connected to Y-input of oscilloscope
B. modulated signal and modulating signal both are connected to X-input of oscilloscope
C. modulated signal is connected to X-input and modulating signal to Y-input
D. modulatedsignal is connected to Y-input and modulating signal to X-input

94. An amplitude modulated current is given by i = 10 11 + 0.5 sin 6280 t] sin (3.14 x 105)t. The modulation index of the wave is
A.0.1
B.0.5
C.10%
D.1

95. When Pc is the power of the unmodulated signal and m is the modulation index then power of the modulated signal is given by
A. mPc
B. m2
C.m1
D.m

96. For bradcasting purpose, full AM signal is preferred to SSSB signal because
A. it requires large bandwidth
B. generation of full AM is easier
C. detection of full AM is simpler
D. none of the above

97. In amplitude modulation if modulation index is more than 1 than
A. the bandwidth will increase
B. there will be interference with other signals
C. efficiency of transmission will improve
D. the wave will get distorted

98. In grid bias modulation system the power required for modulating amplifier,
A. is negligibly low since grid is negative
B. is large as compared to that for plate modulation
C. is almost the same as compared with Plate modulation
D. is small as compared to that for plate modulation

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