Digital Communications Questions and Answers – Noise Parameters

This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Noise parameters”.

1. Noise figure measures the
a) Power degradation
b) Noise degradation
c) SNR degradation
d) None of the mentioned
View Answer

Answer: c
Explanation: Noise figure relates the SNR of the input to SNR of the output. It measures the SNR degradation caused by the network.

2. Noise figure is a parameter that represents a ______ of the system.
a) Noisiness
b) Efficiency
c) Maximum output
d) Maximum power handling capacity
View Answer

Answer: a
Explanation: Noise figure is a parameter that represents the noisiness of a two port network or device such as an amplifier, compared with a reference noise.

3. When two networks are connected in series, its composite noise figure can be given as
a) F1+(F2-1)/G1
b) F1-(F2-1)/G1
c) F2+(F1-1)/G1
d) F1G1+(F2-1)
View Answer

Answer: a
Explanation: When two networks are connected in series, the composite noise figure can be written as F1+(F2-1)/G1.
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4. The space window region ranges from
a) 1GHz to 10 GHz
b) 10GHz to 100GHZ
c) 5GHz to 50GHz
d) 1MHz to 10MHz
View Answer

Answer: a
Explanation: There is a region between 1GHz and 10GHz where the temperature will be lowest. This region is called as microwave window or space window.

5. Atmospheric window region is used for
a) Satellite communication
b) Deep-space communication
c) Satellite & Deep-space communication
d) None of the mentioned
View Answer

Answer: c
Explanation: The region between 1GHz and 10GHz is called as space window or atmospheric window. Here the temperature will be the lowest. This region is used for satellite communication and deep-space communication.
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6. Which parameter is referred to as receiver sensitivity?
a) S/N ratio
b) G/T ratio
c) EIRP
d) PR/N0
View Answer

Answer: b
Explanation: The figure of parameter G/T0 is called as receiver sensitivity.

7. What are the functions of satellite repeaters?
a) Re transmits
b) Regenerates
c) Reconstitutes
d) All of the mentioned
View Answer

Answer: d
Explanation: Satellite repeaters re transmit the message received. It regenerates, demodulates and reconstitutes the digital information embedded in the received waveform.
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8. What are the functions of non-regenerative repeaters?
a) Amplifies
b) Re transmits
c) Amplifies & Re transmits
d) None of the mentioned
View Answer

Answer: c
Explanation: A non regenerative repeaters can be used with many different modulation formats. It only amplifies and re transmits the message received.

9. In which repeaters uplink is decoupled from the downlink?
a) Regenerative
b) Non regenerative
c) Regenerative & Non regenerative
d) None of the mentioned
View Answer

Answer: a
Explanation: The principal advantage of regenerative repeaters over non regenerative repeaters is that the uplink is decoupled from the downlink so that the uplink noise is not transmitted on the downlink.
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10. AM-to-AM conversion brings about
a) Amplitude variation
b) Phase variation
c) Frequency variation
d) None of the mentioned
View Answer

Answer: a
Explanation: AM-to-AM conversion is a phenomenon common to non linear devices and it undergoes a non linear transformation and results in amplitude variation.

11. AM-to-PM conversion brings about
a) Amplitude variation
b) Phase variation
c) Frequency variation
d) None of the mentioned
View Answer

Answer: b
Explanation: AM-to-PM conversion is another common phenomenon in non linear devices. It brings about phase variation that can effect the error performance.

Sanfoundry Global Education & Learning Series – Digital Communications.

To practice all areas of Digital Communications, 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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