162. In a VSB system, a modulating frequency of 3 MHz results in a sideband power of 25 watts. If the carrier power is 100 watts, depth of modulation is

A.25%

B.50%

C.75%

D.100%

163. One of the following is a disadvantage of the VSB system

A. It conserves bandwidth

B. It results in a power boost of low video frequencies

C. It overcomes the problem of low video frequency attenuation

D. It is neither a DSB system nor an SSB system

164. In the spectrum of a frequency modulated wave

A.a) the number of significant sidebands depend upon modulation index

B. carrier frequency cannot disappear

C.carrier frequency vanishes when modulation indexis large

D.(e) none of these

165. In a modulation system, the modulating voltage remains the same, the modulation index is halved when the modulating frequency is doubled, the system is

A. AM

B. FM

C. PM

D. Any one of the three above

166. In amplitude modulation,

A. the time gap between adjacent maximum and minimum values of the modulated envelope is independent of frequency of intelligence

B. maximum value of amplitude of modulating signal does affect the time separation of modulated envelope's maximum and minimum

C. separation of successive maximum and minimum of modulated envelope on time-axis is inversely proportional to the frequency of modulating signal

D. none of these

167. Percentage modulation in an AM signal is

A. (Em/E d x 100

B.(E,./Em) x 100E ?E

C.mx 100

D. none of these

168. Signal at the output of a AM modulator is given by e = 10(1 + 0.64 sin 6280 t) sin 10? t Depth of modulation is

A.0.64%

B.0.80%

C.64%

D.80%

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