# Analog Communication Test - 1

15 Questions | Total Attempts: 115  Settings  • 1.
Noise gets added in the communication system in
• A.

• B.

Transmitter

• C.

Channel

• D.

Transducer

• 2.
A 1 MHz sinusoidal carrier is amplitude modulated by a sinusoidal message signal with time period of 100 micro sec. Which of the frequencies will not be present in the modulated signal ? (DSB-FC modulation)
• A.

1000 KHz

• B.

990 KHz

• C.

1030 KHz

• D.

1010 KHz

• 3.
The hilbert transform of sinw1t - cosw2t is
• A.

Cosw1t + sinw2t

• B.

- cosw1t - sinw2t

• C.

- cosw1t + sinw2t

• D.

cosw1t - sinw2t

• 4.
Consider sinusoidal modulation in an AM system. Assuming no overmodulation, the modulation index ( μ ) when the maximum and minimum values of the envelope , respectively, are 3V and 2 V is
• 5.
What will be the minimum value of 'Ac' required to get the positive envelope of amplitude modulated wave given as  SAM(t) = Ac coswct + 4 coswct coswmt .
• 6.
The output value of  the envelope detector when input applied is 3 coswot + 4 sinwot
• A.

5

• B.

7

• C.

25

• D.

1

• 7.
Let m(t) = cos(2 π * fm *t) be the message signal & c(t)= 5 cos(2 π *fc*t) be the carrier. Both m(t) and c(t) are used to generate an AM modulated signal. The modulation index of the generated AM signal is 0.5. Then, transmission efficiency of the signal will be_______
• A.

1/5

• B.

1/9

• C.

1/8

• D.

1/4

• 8.
Let m(t)= 2 coswmt and c(t)= 4 coswct be the message and carrier signal respectively. Further, m(t) and c(t) is used to generate the DSB-SC signal. Then, total transmission power of modulated signal will be_____
• A.

8

• B.

32

• C.

16

• D.

2

• 9.
Hilbert transform is used in the generation of
• A.

SSB-SC

• B.

DSB-SC

• C.

DSB-FC

• D.

VSB

• 10.
Ring modulator is used in the generation of ________ signal and the no. of diodes used in this circuit is_____
• A.

SSB_SC, 2

• B.

DSB-SC, 3

• C.

DSB-FC, 4

• D.

DSB-SC, 2

• 11.
In AM
• A.

Bandwidth is infinite

• B.

Carrier power is constant

• C.

Total transmitted power is constant

• D.

Sideband power is always constant

• 12.
A message signal is amplitude modulated with modulation index value of '1' . Further, it is modulated to SSB-SC signal. Calculate the percentage of power saved in SSB-SC compared to AM. (approximate value)
• A.

80

• B.

83.33

• C.

62.5

• D.

50

• 13.
The bandwidth required to transmit a SSB-SC signal when message signal is given as m(t) = 2 cos(2 π *5*t).
• 14.
An AM signal with a carrier power of 80 watts has 10 watts power in each sideband. What is the modulation index value.
• A.

0.5

• B.

0.707

• C.

0.577

• D.

1

• 15.
Power requirement is least in
• A.

DSB-FC

• B.

DSB-SC

• C.

SSB-SC

• D.

VSB Back to top