-:PCE:-
MCQ Question Principles of communication engineering
:-
1. Modulation is done in …………..
Transmitter
Radio receiver
Between transmitter and
radio receiver
None of the above
2.
In a transmitter ……………. oscillator is used
Hartley
RC phase-shift
Wien-bridge
Crystal
3.In
India, ……………. modulation is used for radio transmission
Frequency
Amplitude
Phase
None of the above
4.In
an AM wave useful power is carrier by ………….
Carrier
Sidebands
Both sidebands and
carrier
None of the above
5.In
amplitude modulation, bandwidth is ……………. the audio signal frequency
Thrice
Four times
Twice
None of the above
6.In
amplitude modulation, the ………… of carrier is varied according to the strength
of the signal.
Amplitude
Frequency
Phase
None of the
above
7.
In an AM wave, the majority of the power is in …………….
Lower sideband
Upper sideband
Carrier
None of the abo
8.At
100% modulation, the power in each sideband is ………………… of that of carrier
50%
40%
60%
25%
9.Overmodulation
results in …………..
Weakening of the signal
Excessive carrier power
Distortion
None of the
above
10.Demodulation
is done in …………
Receiving antenn
Transmitter
Radio receiver
Transmitting
antenna
11. If
level of modulation is increased ……………. power is increased
Carrier
Sideband
Carrier as well as sideband
None of the
above
12. In
TV transmission, picture signal is ……………… modulated
Frequency
Phase
Amplitude
None of the
above
13.In
a radio receiver, noise is generally developed at ………….
IF stage
Receiving antenna
Audio stage
RF stage
14. Superhertodyne
principle refers to
Using a large number of amplifier stages
Using a push-pull circuit
Obtaining lower fixed intermediate
frequency
None of the
above
15. If
a radio receiver amplifies all the signal frequencies equally well, it is said
to have
Sensitivity
Selectivity
Distortion
Fidelity
16.Most
of the amplification in a superhetrodyne receiver occurs at ………. stage
IF
RF amplifier
Audio amplifier
Detector
17. In
superhetrodyne receiver, the input at mixer stage is ………
IF and RF
RF and AF
IF and AF
RF
and local oscillator signal
18.The
major advantage of FM over AM is …………..
Reception is less noisy
Higher carrier frequency
Smaller bandwidth
Small frequency
deviation
19.When
the modulating signal controls the frequency of the carrier, we get……….
Phase modulation
Amplitude modulation
Frequency modulation
May be any one of the above
20.The
IF is 455 kHz. If the radio receiver is tuned to 855 kHz, the local oscillator
frequency is ………….
455 kHz
1310 kHz
1500 kHz
1520 kHz
21.If
Amin = 40 and Amax = 60, what is the percentage of modulation?
20 %
40 %
50 %
10 %
22.In
a radio receiver, we generally use ………….. oscillator as a local oscillator
Crystal
Wien-bridge
Phase-shift
Hartle
23.A
100 V carrier is made to vary between 160 V and 40 V by the signal. What is the
modulation factor?
3
6
5
None of the
above
24.In
a superhetrodyne receiver, the difference frequency is chosen as the IF rather
than the sum frequency because …………….??
The difference frequency is closer to oscillator
frequency
Lower frequencies are easier to amplify
Only the difference frequency can be modulated
None of the
above
25. In a TRF radio receiver, the RF and detection stages
are tuned to
Radio frequency
IF
Audio frequency
None of the
above
26.What
is the carrier frequency in an AM wave when its highest frequency component is
850Hz and the bandwidth of the signal is 50Hz?
a. 80 Hz
b. 695 Hz
c. 625 Hz
d.
825 Hz
27.Noise
figure of merit in SSB modulated signal is
a. 1
b. Less than 1
c. Greater than 1
d. None of the above
28.For
low level modulation, amplifier used is
a. Class A
b. Class C
c. Class A & C
d. None of the
above
29.Function
of RF mixer is
a. Addition of two signals
b. Multiplication of two signals
c. Rejection of noise
d. None of the
above
30.Advantage
of using VSB transmission is
a. Higher bandwidth than SSB
b. Less power required as compared to DSBSC
c. Both a and b
d. None of the
above
31.Advantage
of using a high frequency carrier wave is
a. Signal can be transmitted over very long distances
b. Dissipates very small power
c. Antenna height of the transmitter is reduced
d. All of the above
32.Bandwidth
required in SSB-SC signal is (fm is modulating frequency):
a. 2fm
b. < 2fm
c. > 2fm
d. fm
33.For
over modulation, the value of modulation index m is a. m < 1
a. m < 1
b. m = 1
c. m > 1
34.Demodulation is:
a. Detection
b. Recovering information from modulated signal
c. Both a and b
d. None of the
above
35.Calculate
the side band power in an SSBSC signal when there is 50% modulation and the
carrier power is 50W.
2/2
a. 50 W
b. 25 W
c. 6.25 W
d. 12.5 W:
36.Disadvantage
of using a DSB or SSB signal modulation is
Difficult to recover information at the receiver
b. Carrier has to be locally generated at receiver
c. Both a and b are correct
d. None of the
above
37.
Types of analog modulation are:
a. Phase modulation
b. Frequency modulation
c. Amplitude modulation
d. All of the above
38.Advantages
of analog communication over digital communication are:
a. Data rate is low
b. Less transmission bandwidth is required
c. Synchronization is not needed
d. All of the above
39.Radio
waves travel through
a. Electromagnetic waves
b. Water
c. Wires
d. Fiber optic
cable
40.
USB (Upper Side Band) is the band of frequency
a.Above the carrier frequency
b. Includes the carrier frequency
c. That lies in AM spectrum
d.
Both a and c are correct
41.In
PM the information is transmitted using _______ .
a. Change in frequency
b. Change in amplitude
c. Change in phase of the carrier
42.FM can be generated using
PM by _______ .
a. Passing the modulating signal through a
low pass filter
b. Passing the modulating signal through a high pass
filter
c. Using the pre-emphasis
d. Using the
de-emphasis
43.
Noise immunity of PM is _______
a. Better than AM and FM
b. Worse than AM and FM
C.
Better than AM but worse than FM
44.Amplitude
of PM wave ______
a. remain constant
b. change in proportion with the modulating voltage
c. change in
proportion with the modulating frequency
45.The
equation for the modulated PM wave is given by
a. 5 sin (2 π × 106 t )
b. 5 sin 1000 t + 5 sin 106 t
c. 5 sin ( 2 π × 106 t + 10 sin 6280 t )
d. 5 sin ( 2 π
× 106 t – 10 sin 6280 t )
46.As
compared to tuned radio frequency receivers which of the following is the
advantage of using superheterodyne receivers?
A. High gain and better sensitivity
B. Better selectivity at high frequencies
C. Stability
D. Noise suppression
47.In
a radio receiver, if the intermediate frequency is too low
A. High gain and better sensitivity
B. Better selectivity at high frequencies
C. Stability
D. Noise
suppression
48.Which
of the following oscillator is generally not used at VHF?
A. Colpitts oscillator
B. Clapp oscillator
C. Armstrong oscillator
D. Ultra Audio oscillator
49.The
output of a diode detector contains
A. D.C. voltage
B. modulating signal
C. RF ripple
D. all of the above
50. In
a radio receiver, if the intermediate frequency is too low
A. Image-frequency rejection will improve
B. Selectivity will be too sharp
C. The frequency selectivity of the local oscillator will
have to be lowered
D. All of the above
…………THANKYOU……
ABHISHEK
KUMAR MAURYA…..
