Digital Communications Questions and Answers – Digital Communication System – 2

This set of tough Digital Communication Questions & Answers focuses on “Digital Communication System”.

1. Which are the common transmission media used in digital communication system?
a) Coaxial cable
b) Twisted copper cable
c) Radio frequency bands
d) All of the mentioned
View Answer

Answer: d
Explanation: Some of the commonly used physical transmission media are twisted copper cable, good quality coaxial cable and radio frequency bands.

2. The basic transmission-reception system is a ______ system.
a) Two block system
b) Three block system
c) Four block system
d) None of the mentioned
View Answer

Answer: b
Explanation: The basic transmission-reception consists of three blocks – transmitter, transmission medium, receiver.

3. Modulation channel consists of
a) Amplifier
b) Signal processing units
c) Amplifier & Signal processing units
d) None of the mentioned
View Answer

Answer: c
Explanation: When information is transmitted through large distance it must be amplified. Modulation channel consists of an amplifier and other signal processing units.
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4. Modulation channel does not accept an analog input signal.
a) True
b) False
View Answer

Answer: b
Explanation: Modulation channel accepts analog signal as input and delivers another version of modulated signal as analog waveform.

5. If operating frequency bands are higher ______ is available.
a) Smaller bandwidth
b) Larger bandwidth
c) Smaller & Larger bandwidth
d) Cannot be determined
View Answer

Answer: b
Explanation: Larger bandwidth is available when operating frequency bands are higher.

6. Ground wave communication occurs in
a) Low frequency band
b) Medium frequency band
c) Low & Medium frequency band
d) None of the mentioned
View Answer

Answer: c
Explanation: Ground wave communication can take place in both low frequency and medium frequency bands.

7. Sampling theorem is used for converting
a) Continuous time signal to discrete
b) Discrete to continuous time signal
c) Continuous time signal to discrete & vice versa
d) None of the mentioned
View Answer

Answer: c
Explanation: Sampling theorem is used for converting continuous time signal to discrete type signal and vice versa.
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8. A signal can be recovered from its sample by using
a) Low pass filter
b) High pass filter
c) Band pass filter
d) Band stop filter
View Answer

Answer: a
Explanation: A signal can be recovered from its sampled version by using an ideal low pass filter.

9. Which is practically realizable?
a) A train of pulses
b) Impulse train
c) All of the mentioned
d) None of the mentioned
View Answer

Answer: a
Explanation: A train of pulses with narrow bandwidth is realizable than the impulse train.
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10. In flat top sampling scheme, ______ is kept constant after sampling.
a) Amplitude
b) Phase
c) Frequency
d) Time period
View Answer

Answer: a
Explanation: In flat top sampling scheme, the amplitude is kept constant after sampling.

11. Loop filter is a ______ used to reduce noise.
a) Low pass filter
b) High pass filter
c) Band pass filter
d) Band reject filter
View Answer

Answer: a
Explanation: Loop filter is a low pass filter used to reduce noise.

Sanfoundry Global Education & Learning Series – Digital Communications.

To practice tough questions and answers on all areas of Digital Communication, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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