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ECE Objective Questions { Analog Communication System }

120. AGC voltage is applied to the stages which are
A. before the detector stage
B. after the detector stage
C. either before or after the detector stage
D. none of the above

121. Which one of the following is not necessarily an advantage of the phase cancellation method of obtaining SSB over the filter method?
A. It is possible to generate SSB at any frequency
B. SSB with lower audio frequencies present can be generated
C. switching from one side band to the other is simpler
D. there are more balanced modulators; therefore the carrier is suppressed better.

122. A pilot carrier in SSB is provided
A. to reduce noise
B. as an auxiliary source of power
C. for reducing power consumption
D. for frequency stabilisation

123. The upper and lower side frequencies for 3 kHz audio modulation with a 27 MHz carrier frequency will be
A. 30 and 24 MHz
B. 27.3 and 26.7 MHz
C. 27.03 and 26.97 MHz
D. 27.003 and 26.997 MHz

124. The unit of modulation index is
A. Hertz
D. no unit

125. The type of emission of the standard AM radio broadcast band is
A.A 5C
C. A3
D. F3

126. In FM the carrier deviation is determined bY
A. modulating voltage
B. frequency
C. either of the above
D. none of the above

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