# Analog Communications Questions and Answers – Frequency Translation

This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Frequency Translation”.

1. FSK stands for ________
a) Frequency Segregation Keying
b) Frequency Section Keying
c) Frequency Signal Keying
d) Frequency Shift Keying

Explanation: FSK stands for Frequency Shift Keying. In FSK, information is transmitted through discrete frequency changes in the carrier signal.

2. When analyzing a transmission line, its inductance and capacitance are considered as _________
a) distributed
b) lumped
c) equal reactances
d) equal impedances

Explanation: For a transmission line, inductance and capacitance are two components that are considered as distributed.

3. What effect will be seen on the resistance of a wire if we increase the frequency?
a) it will also increase
b) it starts to decrease
c) it will remain same
d) it starts changing periodically

Explanation: Skin effect becomes more and more apparent as frequency increases as skin depth becomes smaller. It is due to alternating current flowing through the outer surface of conducting material. It refers to the increase of wire resistance with frequency.

4. What is speed of radio waves in free space?
a) 3 x 106 m/s
b) 3 x 109 m/s
c) 300 x 106 m/s
d) 300 x 109 m/s

Explanation: he speed of radio waves in free space is same as the speed of light which is 3 x 108 m/s. It cal also be written as 300 x 106.

5. An antenna has “gain” as compared to ________
a) Helical antenna
b) Marconi antenna

Explanation: Isotropic radiator is considered as an ideal antenna. So all the gains of any antenna is estimated by comparing with it only.
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6. Ground waves are most effective when _________
a) it is above about 20MHZ
b) it is below about 3MHz
c) it is at microwave frequencies
d) usually in the UHF range

Explanation: Ground wave is generally preferred for long distance communication using frequencies that are below 3MHz. It can be used for short distance communication by using frequencies between 3 and 30MHZ.

7. The microwave frequency range is considered to start at ________
a) 1 GHz
b) 10 GHz
c) 100 GHz
d) 5 GHz

Explanation: Microwave frequency range is considered to be start at 1 GHz. It is standard and fixed.

8. What is the approximate reliability of a microwave system?
a) 90%
b) 99%
c) 99.99%
d) 90.99%

Explanation: Microwave system is mostly known for its reliability. Its reliability is of the order of 99.99%.

9. Which modulation is used by a microwave system?
a) FM
b) SSB
c) QAM
d) Either FM or SSB or QAM

Explanation: Microwave system is used for point-to-point communication links, which is the communication between two nodes. It can either use frequency modulation or single sideband modulation or quadrature modulation.

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