Assertion (A): If a carrier is modulated by three sine waves and m1, m2, m3 are the modulation indices, the total modulation index mt is mt = (m12 + m22 + m32)0.5Reason (R): An AM, higher the level of modulation, lower is the audio power required to produce modulation.

Both A and R are correct and R is correct explanation of A

Both A and R are correct but R is not correct explanation of A

When a wave reaches the open circuited end of a line

all the forward energy is reflected by the open circuit

all the forward energy is absorbed by the open circuit

a small portion of energy is radiated into atmosphere and the remaining energy is reflected

The complete video signal consists of

video signal corresponding to picture information only

video signal and synchronising pulses

video signal, synchronising pulses and blanking pulses

video signal corresponding to picture information only

video signal and blanking pulses

Which of the following is not true as regards communication receiver?

It can be used, besides communication, for detection in high frequency bridges

It is exactly same as radio receiver used in households

It can be used, besides communication, for detection in high frequency bridges

It is designed to perform the task of low and high frequency reception better than in household receiver

Its tuning and operation are more complicated than those in household receiver

Assertion (A): Stubs, directional couplers and baluns are very commonly used in communication systemsReason (R): Characteristic impedance of a line is an important parameter.

Both A and R are correct and R is correct explanation of A

Both A and R are correct but R is not correct explanation of A

Assertion (A): SSB and ISB receivers have good S/N ratioReason (R): SSB and ISB receivers have good suppression of adjacent channels.

Both A and R are correct and R is correct explanation of A

Both A and R are correct but R is not correct explanation of A

De-emphasis circuit is used

to attenuate mid-band frequencies

The image frequency of a superheterodyne receiver is

independent of the frequency of tuning

created within the receiver itself

not rejected by IF tuned circuits

independent of the frequency of tuning

due to insufficient adjacent channel rejection

Which one of the following is correct?

Coding deliberately introduces redundancy into messages

Coding reduces the noise in the signal

Coding deliberately introduces redundancy into messages

Coding increases the information rate

Coding increases the channel bandwidth

In AM increased depth of modulation increases __________ and in FM with increased depth of modulation __________ increases.

total transmitted power, bandwidth

bandwidth, total transmitted power

total transmitted power, sideband power

Which of the following is true as regards telephone systems?

A smaller capacity carrying a larger load operates more efficiently than a larger capacity

A larger facility carrying a larger load operates less efficiently than a smaller capacity

A larger facility carrying a lesser load operates more efficiently than a smaller capacity

A larger facility carrying a larger load operates more efficiently than a smaller capacity

A smaller capacity carrying a larger load operates more efficiently than a larger capacity

In a television camera tube, scanning of a picture is done

line by line from right to left

line by line from left to right

line by line from right to left

line by line from top to bottom

line by line from bottom to top

A balanced modulator circuit uses

two triodes with different V-I characteristics

two identical diodes with same V-I characteristics

two triodes with different V-I characteristics

two diodes with different V-I characteristics

For FM, which of the following statement is not true?

The bandwidth increases as modulation index is increased

The total power remains constant with respect to modulation index

Assertion (A): In AM the amplitude of carrier is made proportional to the instantaneous amplitude of modulating waveReason (R): In AM, frequency of side band = frequency carrier frequency of modulating wave.

Both A and R are correct and R is correct explanation of A

Both A and R are correct but R is not correct explanation of A

Which of the following is the disadvantage of PDM and PPM?

It requires pulses of larger widths

More samples are needed per second

More powerful transmitter is required

Which is most important subsystem for recovering and reconstructing signal in a TDM system?

Synchronization ckt for proper timing

Envelope detector followed by a low pass filter

Synchronization ckt for proper timing

Bandpass filter to segregate channels

Coherent detector to ensure frequency and phase connection

Which one of the following is an indirect way of generating FM?

Reactance bipolar transistor modulator

combines five groups into a super group

interleaves pulses belonging to different transmissions

combines five groups into a super group

stacks 24 channels in adjacent frequency slots

Pressing a key on telephone set generates two frequencies. The basis for selection of these frequencies is

the harmonics of one frequency should not be mistaken for the other frequency

the audio input to the handset transmitter should not be mistaken for a key pressing

A band limited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through

an ideal low pass filter with the appropriate bandwidth

The number of repeaters in a coaxial cable link depends on

the number of coaxial cables in the tube

In binary data transmission DPSK is preferred to PSK because

for a given energy per bit, the probability for zero is less

a coherent carrier is not required to the generated at the receiver

for a given energy per bit, the probability for zero is less

the 180 phase shifts of the carrier

more protection is provided against impulse noise

consists of erect channels only

has a frequency range of 60 to 108 kHz

consists of erect channels only

is formed at group translating equipment

9294 + Mcqs in Electronics and Communication Engineering in Engineering Page 183 McqOptions

9101.	The number of spectral component of impulse wave is
A.	1
B.	0
C.	2
D.
Answer» E.

Discussion

9102.	Assertion (A): If a carrier is modulated by three sine waves and m₁, m₂, m₃ are the modulation indices, the total modulation index m_t is m_t = (m₁² + m₂² + m₃²)^0.5 Reason (R): An AM, higher the level of modulation, lower is the audio power required to produce modulation.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R are correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» D. A is wrong but R is correct

Discussion

9103.	Typical value of power consumption of TV transmitter is
A.	0.5 kVA
B.	2 kVA
C.	50 kVA
D.	1000 kVA
Answer» D. 1000 kVA

Discussion

9104.	When a wave reaches the open circuited end of a line
A.	all the forward energy is reflected by the open circuit
B.	all the forward energy is absorbed by the open circuit
C.	a small portion of energy is radiated into atmosphere and the remaining energy is reflected
D.	either (a) or (b)
Answer» D. either (a) or (b)

Discussion

9105.	The orbital period of a geostationary communication satellite is
A.	12 hours
B.	24 hours
C.	36 hours
D.	48 hours
Answer» C. 36 hours

Discussion

9106.	The complete video signal consists of
A.	video signal and synchronising pulses
B.	video signal, synchronising pulses and blanking pulses
C.	video signal corresponding to picture information only
D.	video signal and blanking pulses
Answer» C. video signal corresponding to picture information only

Discussion

9107.	Which of the following is not true as regards communication receiver?
A.	It is exactly same as radio receiver used in households
B.	It can be used, besides communication, for detection in high frequency bridges
C.	It is designed to perform the task of low and high frequency reception better than in household receiver
D.	Its tuning and operation are more complicated than those in household receiver
Answer» B. It can be used, besides communication, for detection in high frequency bridges

Discussion

9108.	Which one of the following frequency bands is allocated by ITU (International Telecomm. Union) for DBS - (Direct Broadcast service) also referred as DTH - (Direct to Home service)?
A.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-1.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-2.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-3.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-4.png">
Answer» C. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-3.png">

Discussion

9109.	FM broadcast lies in which band?
A.	HF
B.	SHF
C.	UHF
D.	VHF
Answer» E.

Discussion

9110.	Which colour picture tube uses slotted aperture mask?
A.	Trinitron
B.	Shadow mask tube
C.	PIL
D.	None of the above
Answer» D. None of the above

Discussion

9111.	If the circumference of a spherical target is between 1 to 10 wavelength in a radar system, the situation is called
A.	resonance region
B.	Rayleigh region
C.	optical region
D.	binomial region
Answer» B. Rayleigh region

Discussion

9112.	For TV broadcast, picture signal is modulated in
A.	SSB
B.	VSB
C.	FM
D.	AM
Answer» E.

Discussion

9113.	Assertion (A): Stubs, directional couplers and baluns are very commonly used in communication systems Reason (R): Characteristic impedance of a line is an important parameter.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R are correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

9114.	Audio frequency range lies between
A.	20 Hz and 20 kHz
B.	20 kHz and 20 MHz
C.	2 MHz and 20 MHz
D.	20 MHz and 200 MHz
Answer» B. 20 kHz and 20 MHz

Discussion

9115.	Assertion (A): SSB and ISB receivers have good S/N ratio Reason (R): SSB and ISB receivers have good suppression of adjacent channels.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R are correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

9116.	De-emphasis circuit is used
A.	to attenuate high frequencies
B.	to attenuate low frequencies
C.	to attenuate mid-band frequencies
D.	None of the above
Answer» B. to attenuate low frequencies

Discussion

9117.	Some features of RF stage in good radio receivers is It increases sensitivity by providing amplification to RF signal It eliminates image frequency interference It increases selectivity It reduces noise level Which of the above are true?
A.	1, 2 and 3 only
B.	1, 2 and 4 only
C.	2, 3, 4 only
D.	1, 2, 3, 4
Answer» E.

Discussion

9118.	During amplitude modulation, the phase angle of the modulating voltage changes by
A.	0
B.	45
C.	90
D.	180
Answer» B. 45

Discussion

9119.	The image frequency of a superheterodyne receiver is
A.	created within the receiver itself
B.	not rejected by IF tuned circuits
C.	independent of the frequency of tuning
D.	due to insufficient adjacent channel rejection
Answer» C. independent of the frequency of tuning

Discussion

9120.	Image frequency rejection mainly depends upon
A.	detector
B.	mixer
C.	IF
D.	RF
Answer» B. mixer

Discussion

9121.	The figure shows a simple detector circuit for amplitude modulated wave v(t) = (1 + m cos _mt) cost _ct. If the detector is to follow the envelope of modulated wave at all times the extent of modulation m must be less than or equal to m₀ where m₀ is given by equation
A.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-2.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-3.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-4.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-5.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-3.png">

Discussion

9122.	Which of the following is most likely to be found in an SSB transmitter?
A.	Class A, RF output amplifier
B.	Class B, RF amplifier
C.	Tuned modulator
D.	Class C, audio amplifier
Answer» C. Tuned modulator

Discussion

9123.	Which one of the following is correct?
A.	Coding reduces the noise in the signal
B.	Coding deliberately introduces redundancy into messages
C.	Coding increases the information rate
D.	Coding increases the channel bandwidth
Answer» B. Coding deliberately introduces redundancy into messages

Discussion

9124.	Huffman code is also known as redundancy code
A.	True
B.	false
C.	in some cases
D.	depend upon efficiency
Answer» B. false

Discussion

9125.	A paraboloid reflector has mouth diameter D meters, wavelength meters. Its beam width is equal to
A.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-1.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-2.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-3.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-4.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-2.png">

Discussion

9126.	In AM increased depth of modulation increases __________ and in FM with increased depth of modulation __________ increases.
A.	total transmitted power, bandwidth
B.	bandwidth, bandwidth
C.	bandwidth, total transmitted power
D.	total transmitted power, sideband power
Answer» B. bandwidth, bandwidth

Discussion

9127.	In a DM system, the granular noise occurs when modulating signal
A.	decrease Rapidly
B.	increase
C.	has high frequency component
D.	change within step size
Answer» D. change within step size

Discussion

9128.	In communication receivers the fidelity is provided by
A.	audio stage
B.	detector range
C.	mixer stage
D.	all of the above
Answer» B. detector range

Discussion

9129.	Which of the following is true as regards telephone systems?
A.	A larger facility carrying a larger load operates less efficiently than a smaller capacity
B.	A larger facility carrying a lesser load operates more efficiently than a smaller capacity
C.	A larger facility carrying a larger load operates more efficiently than a smaller capacity
D.	A smaller capacity carrying a larger load operates more efficiently than a larger capacity
Answer» D. A smaller capacity carrying a larger load operates more efficiently than a larger capacity

Discussion

9130.	SSB can be generated by
A.	filter method
B.	phase shift method
C.	weaver's method
D.	none of the above
Answer» E.

Discussion

9131.	In a television camera tube, scanning of a picture is done
A.	line by line from left to right
B.	line by line from right to left
C.	line by line from top to bottom
D.	line by line from bottom to top
Answer» B. line by line from right to left

Discussion

9132.	A balanced modulator circuit uses
A.	two identical diodes with same V-I characteristics
B.	two triodes with different V-I characteristics
C.	two diodes with different V-I characteristics
D.	a diode and a triode
Answer» B. two triodes with different V-I characteristics

Discussion

9133.	Which one of the following cannot be used to remove the unwanted sideband in SSB?
A.	Balanced modulator
B.	Phase shift method
C.	Filter system
D.	Third method
Answer» B. Phase shift method

Discussion

9134.	For FM, which of the following statement is not true?
A.	The bandwidth increases as modulation index is increased
B.	The total power remains constant with respect to modulation index
C.	The carrier never becomes zero
D.	All of the above
Answer» D. All of the above

Discussion

9135.	Companding is used in PCM to
A.	reduce bandwidth
B.	increasing S/N ratio
C.	get almost uniform S/N ratio
D.	increase bandwidth
Answer» D. increase bandwidth

Discussion

9136.	Assertion (A): In AM the amplitude of carrier is made proportional to the instantaneous amplitude of modulating wave Reason (R): In AM, frequency of side band = frequency carrier frequency of modulating wave.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R are correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

9137.	Which of the following is the disadvantage of PDM and PPM?
A.	It requires pulses of larger widths
B.	More samples are needed per second
C.	More powerful transmitter is required
D.	None of the above
Answer» D. None of the above

Discussion

9138.	Frequency frogging is used in a carrier system to
A.	conserve frequencies
B.	reduce distortion
C.	reduce cross talk
D.	none of the above
Answer» D. none of the above

Discussion

9139.	Which is most important subsystem for recovering and reconstructing signal in a TDM system?
A.	Envelope detector followed by a low pass filter
B.	Synchronization ckt for proper timing
C.	Bandpass filter to segregate channels
D.	Coherent detector to ensure frequency and phase connection
Answer» B. Synchronization ckt for proper timing

Discussion

9140.	Which one of the following is an indirect way of generating FM?
A.	Armstrong modulator
B.	Varactor diode modulator
C.	Reactance FET modulator
D.	Reactance bipolar transistor modulator
Answer» B. Varactor diode modulator

Discussion

9141.	TDM
A.	can be used with PCM only
B.	interleaves pulses belonging to different transmissions
C.	combines five groups into a super group
D.	stacks 24 channels in adjacent frequency slots
Answer» C. combines five groups into a super group

Discussion

9142.	Pressing a key on telephone set generates two frequencies. The basis for selection of these frequencies is
A.	the harmonics of one frequency should not be mistaken for the other frequency
B.	the audio input to the handset transmitter should not be mistaken for a key pressing
C.	both (a) and (b)
D.	neither (a) nor (b)
Answer» D. neither (a) nor (b)

Discussion

9143.	PA radar means
A.	Phased Array radar
B.	Pulsed Array radar
C.	Pulse Amplitude radar
D.	None of the above
Answer» B. Pulsed Array radar

Discussion

9144.	Dynamic range of hi-fi system is at least
A.	150 dB
B.	120 dB
C.	80 dB
D.	40 dB
Answer» D. 40 dB

Discussion

9145.	A band limited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through
A.	an RC filter
B.	an envelope detector
C.	a PPL
D.	an ideal low pass filter with the appropriate bandwidth
Answer» E.

Discussion

9146.	The number of repeaters in a coaxial cable link depends on
A.	system bandwidth
B.	separation of equalizers
C.	the number of coaxial cables in the tube
D.	none of the above
Answer» B. separation of equalizers

Discussion

9147.	In binary data transmission DPSK is preferred to PSK because
A.	a coherent carrier is not required to the generated at the receiver
B.	for a given energy per bit, the probability for zero is less
C.	the 180 phase shifts of the carrier
D.	more protection is provided against impulse noise
Answer» B. for a given energy per bit, the probability for zero is less

Discussion

9148.	A basic group B
A.	consists of five super groups
B.	has a frequency range of 60 to 108 kHz
C.	consists of erect channels only
D.	is formed at group translating equipment
Answer» C. consists of erect channels only

Discussion

9149.	By the use of which of the following the PPM can be converted to PWM?
A.	A stable multivibrator
B.	Integrator
C.	Monostable multivibrator
D.	Bistable Multivibrator
Answer» E.

Discussion

9150.	Which of the following pulse-time modulation is least used?
A.	PDM
B.	PPM
C.	PWM
D.	PAM
Answer» E.

Discussion

Explore topic-wise MCQs in Engineering.

The number of spectral component of impulse wave is

Assertion (A): If a carrier is modulated by three sine waves and m1, m2, m3 are the modulation indices, the total modulation index mt is mt = (m12 + m22 + m32)0.5Reason (R): An AM, higher the level of modulation, lower is the audio power required to produce modulation.

Typical value of power consumption of TV transmitter is

When a wave reaches the open circuited end of a line

The orbital period of a geostationary communication satellite is

The complete video signal consists of

Which of the following is not true as regards communication receiver?

Which one of the following frequency bands is allocated by ITU (International Telecomm. Union) for DBS - (Direct Broadcast service) also referred as DTH - (Direct to Home service)?

FM broadcast lies in which band?

Which colour picture tube uses slotted aperture mask?

If the circumference of a spherical target is between 1 to 10 wavelength in a radar system, the situation is called

For TV broadcast, picture signal is modulated in

Assertion (A): Stubs, directional couplers and baluns are very commonly used in communication systemsReason (R): Characteristic impedance of a line is an important parameter.

Audio frequency range lies between

Assertion (A): SSB and ISB receivers have good S/N ratioReason (R): SSB and ISB receivers have good suppression of adjacent channels.

De-emphasis circuit is used

Some features of RF stage in good radio receivers is It increases sensitivity by providing amplification to RF signalIt eliminates image frequency interferenceIt increases selectivityIt reduces noise level Which of the above are true?

During amplitude modulation, the phase angle of the modulating voltage changes by

The image frequency of a superheterodyne receiver is

Image frequency rejection mainly depends upon

The figure shows a simple detector circuit for amplitude modulated wave v(t) = (1 + m cos mt) cost ct. If the detector is to follow the envelope of modulated wave at all times the extent of modulation m must be less than or equal to m0 where m0 is given by equation

Which of the following is most likely to be found in an SSB transmitter?

Which one of the following is correct?

Huffman code is also known as redundancy code

A paraboloid reflector has mouth diameter D meters, wavelength meters. Its beam width is equal to

In AM increased depth of modulation increases __________ and in FM with increased depth of modulation __________ increases.

In a DM system, the granular noise occurs when modulating signal

In communication receivers the fidelity is provided by

Which of the following is true as regards telephone systems?

SSB can be generated by

In a television camera tube, scanning of a picture is done

A balanced modulator circuit uses

Which one of the following cannot be used to remove the unwanted sideband in SSB?

For FM, which of the following statement is not true?

Companding is used in PCM to

Assertion (A): In AM the amplitude of carrier is made proportional to the instantaneous amplitude of modulating waveReason (R): In AM, frequency of side band = frequency carrier frequency of modulating wave.

Which of the following is the disadvantage of PDM and PPM?

Frequency frogging is used in a carrier system to

Which is most important subsystem for recovering and reconstructing signal in a TDM system?

Which one of the following is an indirect way of generating FM?

TDM

Pressing a key on telephone set generates two frequencies. The basis for selection of these frequencies is

PA radar means

Dynamic range of hi-fi system is at least

A band limited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through

The number of repeaters in a coaxial cable link depends on

In binary data transmission DPSK is preferred to PSK because

A basic group B

By the use of which of the following the PPM can be converted to PWM?

Which of the following pulse-time modulation is least used?

Assertion (A): If a carrier is modulated by three sine waves and m₁, m₂, m₃ are the modulation indices, the total modulation index m_t is
m_t = (m₁² + m₂² + m₃²)^0.5
Reason (R): An AM, higher the level of modulation, lower is the audio power required to produce modulation.

Assertion (A): Stubs, directional couplers and baluns are very commonly used in communication systems
Reason (R): Characteristic impedance of a line is an important parameter.

Assertion (A): SSB and ISB receivers have good S/N ratio
Reason (R): SSB and ISB receivers have good suppression of adjacent channels.

Some features of RF stage in good radio receivers is
It increases sensitivity by providing amplification to RF signal
It eliminates image frequency interference
It increases selectivity
It reduces noise level
Which of the above are true?

The figure shows a simple detector circuit for amplitude modulated wave v(t) = (1 + m cos _mt) cost _ct. If the detector is to follow the envelope of modulated wave at all times the extent of modulation m must be less than or equal to m₀ where m₀ is given by equation

In AM increased depth of modulation increases and in FM with increased depth of modulation increases.

Assertion (A): In AM the amplitude of carrier is made proportional to the instantaneous amplitude of modulating wave
Reason (R): In AM, frequency of side band = frequency carrier frequency of modulating wave.