# Analog Communications Questions and Answers – Method of Generation of SSB-SC

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This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Method of Generation of SSB-SC”.

1. A duplex arrangement use separate frequencies for transmission.
a) True
b) False

Explanation: In duplex communication, two-way interaction is favourable simultaneously. Thus, a cordless telephone is duplex which uses separate frequencies for transmission in base and portable units.

2. VSB modulation is used in televisions because it avoids phase distortion at low frequencies.
a) True
b) False

Explanation: Vestigial Sideband Modulation (VSB) is a type of amplitude modulation in which the carrier and only one sideband is completely transmitted and the other sideband is partly transmitted. Thus, television production is done using VSB modulation as it reduces bandwidth to half.

3. A cordless telephone that uses separate frequencies for transmission in base and portable units is called _________
a) half duplex
b) duplex
c) simplex
d) one-way communication

Explanation: In duplex communication, two-way interaction is favourable simultaneously. Thus, a cordless telephone is duplex which uses separate frequencies for transmission in base and portable units.
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4. Which polarization is used to reduce the depolarization effect on received waves?
a) Circular polarization
b) Linear polarization
c) Atomic polarization
d) Dipolar polarization

Explanation: In circular polarization at each point the electric field of electromagnetic wave has a constant magnitude but its direction changes as it rotates with time at a steady rate, in a plane perpendicular to the direction of propagation of wave. It is used to reduce depolarization effect on received waves.

5. Circular polarization involves critical alignment between transmitting and receiving antenna.
a) True
b) False

Explanation: In circular polarization at each point the electric field of the electromagnetic wave has a constant magnitude but its direction changes as it rotates with time at a steady rate, in a plane perpendicular to the direction of propagation of the wave. It is used to reduce depolarization effect on received waves. It does not involve alignment between transmitting and receiving antenna.

6. It is only the reflected color that decided the color of an object.
a) True
b) False

Explanation: Color of any object is decided by the reflected color for opaque object and wavelength transmitted through it for transparent object, while both reflector color and wavelength transmitted are considered for a translucent object.

7. What do you understand by the term “carrier” in modulation?
a) voltage to be transmitted
b) resultant wave
c) voltage for which amplitude, phase or frequency can be varied
d) voltage for which amplitude, phase or frequency remains constant

Explanation: Carrier wave is the wave with frequency higher than the message signal, whose certain characteristics like amplitude, phase or frequency are varied with respect to the instantaneous amplitude of the message signal. Thus forming the modulated wave which is the wave to be transmitted.

8. Carrier wave in modulation is a resultant wave.
a) True
b) False

Explanation: Carrier wave is the wave with frequency higher than the message signal, whose certain characteristics like amplitude, phase or frequency are varied with respect to the instantaneous amplitude of the message signal. Thus forming the modulated wave which is the wave to be transmitted.

9. For a low level AM system, amplifier modulated stage must have _________
a) harmonic devices
b) linear devices
c) non-linear devices
d) class A amplifiers

Explanation: In low-level modulation, the generation of amplitude modulated signal takes place at low power levels. The generated AM signal is then amplified using a chain of linear amplifiers, which are required to avoid waveform distortion. Thus, linear devices are used in low level amplitude modulated system.