laboursonline – MCQs, Mock Tests | Electrical measurements Digital Communications MCQs set-11

In finite state machines, output is predicted using

1. Past output
2. Present input
3. Past output & Present input
4. None of the mentioned

✅ Correct Answer: 3

In TCM the signals are decoded using

1. Soft decision decoders
2. Hard decision decoders
3. Soft & Hard decision decoders
4. None of the mentioned

✅ Correct Answer: 1

Trellis coded modulation scheme

1. Has memory
2. Is memory-less
3. Needs more bandwidth
4. None of the mentioned

✅ Correct Answer: 1

In TCM channel capacity can be increased.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Transmission bandwidth depends on

1. Rate of signalling
2. Density of signal points
3. Reduced distance
4. None of the mentioned

✅ Correct Answer: 1

Which determines the error performance in TCM?

1. Reduced distance
2. Free distance
3. Bandwidth
4. None of the mentioned

✅ Correct Answer: 2

The TCM decoder uses

1. Minimum likelihood detector
2. Maximum likelihood detector
3. Does not use redundant bits
4. None of the mentioned

✅ Correct Answer: 2

Flat top sampling of low pass signals

1. Gives rise to aperture effect
2. Implies over sampling
3. Leads to aliasing
4. Introduces delay distortion

✅ Correct Answer: 1

In a delta modulation system, granular noise occurs when the

1. Modulating signal increases rapidly
2. Pulse rate decreases
3. Pulse amplitude decreases
4. Modulating signal remains constant

✅ Correct Answer: 4

A PAM signal can be detected using

1. Low pass filter
2. High pass filter
3. Band pass filter
4. All pass filter

✅ Correct Answer: 1

Coherent demodulation of FSK signal can be performed using

1. Matched filter
2. BPF and envelope detectors
3. Discriminator
4. None of the mentioned

✅ Correct Answer: 1

The use of non uniform quantization leads to

1. Reduction in transmission bandwidth
2. Increase in maximum SNR
3. Increase in SNR for low level signals
4. Simplification of quantization process

✅ Correct Answer: 3

Which of the following requires a synchronizing signal?

1. Single channel PPM system
2. PAM
3. DM
4. All of the mentioned

✅ Correct Answer: 2

A PWM signal can be generated by

1. An astable multi vibrator
2. A monostable multi vibrator
3. Integrating a PPM signal
4. Differentiating a PPM signal

✅ Correct Answer: 2

TDM is less immune to cross-talk in channel than FDM.

1. True
2. False
3.
4.

✅ Correct Answer: 2

In an ideal TDM system, the cross correlation between two users of the system is

1. 1
2. 0
3. Infinity
4. -1

✅ Correct Answer: 2

TDM requires

1. Constant data transmission
2. Transmission of data samples
3. Transmission of data at random
4. Transmission of data of only one measured

✅ Correct Answer: 2

In M-ary FSK, as M increases error

1. Increases
2. Decreases
3. Does not get effected
4. Cannot be determined

✅ Correct Answer: 2

In M-ary FSK as M tends to infinity, probability of error tends to

1. Infinity
2. Unity
3. Zero
4. None of the mentioned

✅ Correct Answer: 3

For non coherent reception of PSK _____ is used.

1. Differential encoding
2. Decoding
3. Differential encoding & Decoding
4. None of the mentioned

✅ Correct Answer: 3

Which modulation technique have the same bit and symbol error probability?

1. BPSK
2. DPSK
3. OOK
4. All of the mentioned

✅ Correct Answer: 4

An amplifier uses ______ to take input signal.

1. DC power
2. AC power
3. DC & AC power
4. None of the mentioned

✅ Correct Answer: 1

Which has 50% maximum power efficiency?

1. Class A
2. Class B
3. Class AB
4. None of the mentioned

✅ Correct Answer: 1

Which generates high distortion?

1. Class A
2. Class B
3. Class C
4. Class AB

✅ Correct Answer: 3

Class B linear amplifiers have maximum power efficiency of

1. 50%
2. 75%
3. 78.5%
4. None of the mentioned

✅ Correct Answer: 3

Which has the maximum power efficiency?

1. Class A
2. Class B
3. Class C
4. Class AB

✅ Correct Answer: 3

Free space in idealization which consists

1. Transmitter
2. Receiver
3. Transmitter & Receiver
4. None of the mentioned

✅ Correct Answer: 3

Properties used to determine stream’s fidelity

1. Sampling rate
2. Bit depth
3. Sampling rate & Bit depth
4. None of the mentioned

✅ Correct Answer: 3

In bipolar codes, pulses can be

1. Positive
2. Negative
3. Absent
4. All of the mentioned

✅ Correct Answer: 4

Delta modulation is ______ conversion.

1. Analog to digital
2. Digital to analog
3. Analog to digital and digital to analog
4. None of the mentioned

✅ Correct Answer: 3

To achieve high signal to noise ratio, delta modulation must use

1. Under sampling
2. Over sampling
3. Aliasing
4. None of the mentioned

✅ Correct Answer: 2

The demodulator in delta modulation technique is

1. Differentiator
2. Integrator
3. Quantizer
4. None of the mentioned

✅ Correct Answer: 2

Source of noise in delta modulation is

1. Granularity
2. Slope overload
3. Granularity & Slope overload
4. None of the mentioned

✅ Correct Answer: 3

When probability of receiving a symbol is 1 then how much information will be obtained?

1. Little information
2. Much information
3. No information
4. None of the mentioned

✅ Correct Answer: 3

In channel encoding procedure

1. Redundancy bits are added
2. Errors are corrected
3. Redundancy bits are added & Errors are corrected
4. None of the mentioned

✅ Correct Answer: 3

Modulation process includes

1. Analog to digital conversion
2. Digital to analog conversion
3. All of the mentioned
4. None of the mentioned

✅ Correct Answer: 2

Switching exists in

1. Point to point communication
2. Broadcast communication
3. Point to point & Broadcast communication
4. None of the mentioned

✅ Correct Answer: 1

Space division has dedicated

1. Paths
2. Time slots
3. Paths & Time slots
4. None of the mentioned

✅ Correct Answer: 1

In time division system, the actual switch is called as

1. Speech memory
2. Cross point
3. Connecting point
4. None of the mentioned

✅ Correct Answer: 1

In time division, connection is established using

1. Data exchange
2. Galvanic connection
3. Data exchange & Galvanic connection
4. None of the mentioned

✅ Correct Answer: 1

Analogue switches provides

1. Good bandwidth
2. Low distortion
3. Low cost
4. All of the mentioned

✅ Correct Answer: 4

Operations performed by switching system

1. Path establishment
2. Information exchange
3. Tariff computation
4. All of the mentioned

✅ Correct Answer: 4

PCM includes the process of

1. Amplitude discretization
2. Time discretization
3. Amplitude & Time discretization
4. None of the mentioned

✅ Correct Answer: 3

For which quantization process is used?

1. Amplitude discretization
2. Time discretization
3. Amplitude & Time discretization
4. None of the mentioned

✅ Correct Answer: 1

Modulation process corresponds to ______ the amplitude, frequency or phase.

1. Switching
2. Keying
3. Switching or keying
4. None of the mentioned

✅ Correct Answer: 3

Which has same probability of error?

1. ASK and FSK
2. ASK and PSK
3. PSK and FSK
4. None of the mentioned

✅ Correct Answer: 3

Which has higher error probability performance?

1. Uni-polar base-band signalling
2. Bipolar base-band signalling
3. ASK
4. FSK

✅ Correct Answer: 2

Time division multiplexing uses

1. High pass filter
2. Commutator
3. High pass filter & Commutator
4. None of the mentioned

✅ Correct Answer: 2

In TDM, at the receiver end, ____ filter is used.

1. Low pass
2. High pass
3. Band pass
4. Band stop

✅ Correct Answer: 1

Which provides more secure communication?

1. CDMA
2. FDMA
3. TDMA
4. None of the mentioned

✅ Correct Answer: 1