# Analog Communications Questions and Answers – Problems of DSBSC

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

1. A Marconi antenna has length equal to ________
a) ʎ4
b) ʎ2
c) 1
d) ʎ8

Explanation: Marconi antenna is like a vertical wire having length one fourth of the working wavelength. Thus, it is a quarter-wave monopole antenna. Since, it was invented by Guglielmo Marconi, so it’s also called Marconi Antenna. It requires a ground plane with very good conductivity. Hence it is also called as a grounded antenna.

2. In a Vidicon camera tube, both sides of the target plate have the coating of antimony tri-sulphide.
a) True
b) False

Explanation: A vidicon camera tube is a type of camera having a photoconductive surface within. In a Vidicon camera tube, the side of target plate facing the light has a coating of Sno2 and the side facing electron gun has a coating of antimony trisulphide.

3. A trigonometric function is a synonym of ________
a) triangular function
b) orthogonal function
c) singular function
d) rectangular function

Explanation: Trigonometric function is the angle expressed as the ratio of two sides of a right-angled triangle that contains the angle. It can also be seen as a synonym of triangular function.

4. White noise is a synonym of ________
a) partition noise
b) shot noise
c) johnson noise
d) transit time noise

Explanation: White noise is an internal noise of communication system having different frequencies present with equal intensities. It can also be called Thermal noise or Johnson noise.

5. Local programmes in a cable TV can be telecast at any frequency.
a) True
b) False

Explanation: There is not a fixed frequency range or bandwidth set for broadcasting of local programs in a cable TV. It can be telecasted at any frequency, depending on the channel of bandwidth available.
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6. Minimum viewing angle of resolution of human eye is ________
a) $$\frac{ʎ}{d}$$
b) $$\frac{1.22ʎ}{d}$$
c) $$\frac{3ʎ}{d}$$
d) $$\frac{2ʎ}{d}$$

Explanation: Minimum resolution of human eye for clear observation is generally $$\frac{1.22ʎ}{d}$$. The diameter of human eye is about 25mm.

7. Power density spectrum of a resistor R can be expressed as ________
a) 2 kTR
b) 1 kTR
c) 0.75 kTR
d) 3 kTR

Explanation: Power Spectral Density is the quantity of power present in a signal in the frequency domain. The Power Density Spectrum of a resistor R can be expressed as 2 kTR where k is Boltzmann’s constant, T is temperature and R is given resistance.

8. VSB is generally used in ________
a) television production
c) telephonic conversations
d) long distance conversations

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

9. A helical antenna is used for satellite tracking due to its __________
b) circular polarization
c) linear polarization
d) good front to back ratio

Explanation: Helical antenna consists conducting wire. These conducting wire is wound around it in the form of helix. It is mainly used for satellite tracking due to its good front to back ratio.

10. What is the typical bandwidth of a 2-wire telephone line?
a) 20 Hz to 6 KHz
b) 300 Hz to 3.4 KHz
c) 20 Hz to 20 KHz
d) 200 Hz to 6.5 KHz

Explanation: A helical antenna is an antenna made of one or more conducting wires wound in the form of a helix. It produces circular polarization, because of which it is highly used in radio telemetry. It is mainly used for satellite tracking due to its good front to back ratio.

Sanfoundry Global Education & Learning Series – Analog Communications.

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