Analog Communication System MCQs

Question 1

Modulated carrier power in FM modulating signal power.

Accepted Answer

is independent of

Answer

decreases with

Answer

increases with

Answer

none of the above

Question 2

high frequencies noise assumes great importance at

Accepted Answer

Transit-time

Answer

Short

Answer

Johnson

Answer

Flicker

Question 3

If the modulation index of an AM wave is changed from 0 to 1 the transmitted power

Accepted Answer

will increase by 50 percent

Answer

will remain unchanged

Answer

will decrease by 50 percent

Answer

will increase by 200 percent

Question 4

A constant-amplitude modulated frequency of 500 kHz causes a carrier to vary between 8798.5 MHz and 8801.5 MHz. the modulation index is

Accepted Answer

3

Answer

2

Answer

4

Answer

6

Question 5

Which of the following statements is correct? In the spectrum of frequency-modulated wave

Accepted Answer

the amplitude of any sideband depends on the carrier modulation index

Answer

the total number of sidebands depends on the modulation index

Answer

the carrier frequency disappears when the modulation index is large

Answer

the carrier frequency cannot disappear

Question 6

The output of transmitter is 100 kW with carrier unmodulated and 132 kW when the carrier is modulated by a sinusoidal wave, then depth of modulation is

Accepted Answer

80

Answer

16

Answer

32

Answer

64

Question 7

The modulating index, for a PM signal, depends upon which of the following?

Accepted Answer

Only the amplitude of the modulating signal

Answer

Only the frequency of the modulating signal

Answer

Both the amplitude and frequency of the modulating signal

Answer

The frequency of the carrier signal amongst other things

Question 8

Which of the following are suppressed by the transmitter in S.S.B.?

Accepted Answer

Carrier and one of the sideband frequencies

Answer

audio and one of the sideband frequencies

Answer

Carrier and audio frequency

Answer

None of the above

Question 9

Regarding the Armstrong modulation system, which of the following statements is incoreect?

Accepted Answer

Equalisation is unnecessary

Answer

Frequency multiplication must be used

Answer

The system is basically phase, not frequency modulation

Answer

AFC is not needed