Analog Communication System MCQs

Question 1

In amplitude modulation,

Accepted Answer

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

Answer

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

Answer

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

Answer

none of these

Question 2

Percentage modulation in an AM signal is

Accepted Answer

(Em/E d x 100

Answer

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

Answer

mx 100

Answer

none of these

Question 3

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

Accepted Answer

64%

Answer

0.64%

Answer

0.80%

Answer

80%

Question 4

In Frequency modulation,

Accepted Answer

carrier frequency varies in accordance with the modulating signal amplitude

Answer

frequency of the carrier remains constant

Answer

carrier frequency varies in accordance with the modulating signal frequency

Answer

none of these

Question 5

An FM signal contains intelligence in

Accepted Answer

its frequency variations

Answer

its amplitude variations

Answer

both amplitude and frequency variations

Answer

none of these

Question 6

In an FM signal, there are

Accepted Answer

infinite number of sidebands

Answer

no sidebands

Answer

two sidebands, upper and lower

Answer

none of these

Question 7

In an FM signal, number of significant sidebands depends upon modulation index. This statement is

Accepted Answer

true

Answer

false

Answer

not necessarily true

Answer

none of these

Question 8

Modulation index of an FM signal of commercial FM radio broadcast is given by

Accepted Answer

75

Answer

25

Answer

50

Answer

none of these

Question 9

Modulation index (mi) in FM is

Accepted Answer

x100Frequency deviation in kHz

Answer

directly proportional to frequency deviation and inversely proportional to the modulating frequency

Answer

given by mf

Answer

(c) directly proportional to modulating signal frequency and inversely proportional to frequency deviation