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Important Questions on Communication Systems

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Physics>Modern Physics>Communication Systems>Elements of a Communication System
The transmitting antenna placed at the top of a tower has a height of 45 m from the ground. The distance between receiving and transmitting antennas is 40 km and the radius of earth is 6400 km. The minimum height (in m at which the receiving antenna is to be placed for satisfactory communication in LOS mode, is
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
An antenna uses electromagnetic waves of frequency 5 MHz. For proper working, the size of the antenna should be
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
For television broadcasting the frequency employed is normally in range,
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A 100 m long antenna is mounted on a 500 m tall building. The complex can become a transmission tower for waves with λ
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A signal is to be transmitted through a wave of wavelength λ, using a linear antenna. The length l of the antenna and effective power radiated Peff will be given, respectively, as-
(K is a constant of proportionality)
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A TV transmitter has a range of 50 km. The height of the TV transmitter is _______ (Radius of the earth Re=6.4×106 m
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
An amplitude modulated waves is represented by expression vm=51+0.6 cos 6280t sin211×104t V. The minimum and maximum amplitudes of the amplitudes modulated wave are, respectively:
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
The increase in the height of the tower of height 200 m to get its coverage range tripled is
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A signal Acosωt is transmitted using ν0sinω0t as carrier wave. The correct amplitude modulated (AM) signal is:
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
The wavelength of the carrier waves in a modern optical fiber communication network is close to:
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
The radius of the Earth is 6400 km. If the height of an antenna is 500 m, then its range is
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
The difference in the refractive index of the fiber core and fiber cladding in step-index fibers is typically
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A repeater in T.V. transmission is
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A 100 V carrier wave is made to vary between 160 V and 40 V by a modulating signal. What is the modulation index?
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
The wireless communication frequency bands for Cellular Mobile Radio (mobile to base station) are in the range of
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Physics>Modern Physics>Communication Systems>Elements of a Communication System

Given below are two statements:

Statement I : A speech signal of 2 kHz is used to modulate a carrier signal of 1 MHz. The bandwidth requirement for the signal is 4 kHz.

Statement II : The side band frequencies are 1002 kHz and 998 kHz. In the light of the above statements, choose the correct answer from the options given below:

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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A TV tower is 120 m high. How much more height is to be added to it, if its coverage range is to become double?
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
In frequency modulated wave
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
In communication system the process of superimposing a low frequency signal on a high frequency wave is known as
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Physics>Modern Physics>Communication Systems>Elements of a Communication System
A carrier wave of peak voltage 14 V is used for transmitting a message signal. The peak voltage of the modulating signal given to achieve a modulation index of 80% will be: