Communication Systems - ECE Questions and Answers

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If an isotropic source is radiating power P in all directions, the electric field at a distance d from the source is proportional to

(P/d)^0.5

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An FM signal has modulating frequency f_m and maximum frequency deviation of δ. The bandwidth will be nearly equal to

2 δ

2f_m δ

f_m δ

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In a cellular communication system, path loss between transmitter and receiver is due to

scattering from building, trees, vehicles and other structure

reason at (a) above and due to reflections from ground only

reason at (a) and (b) above along with reflections from ionosphere only

reasons at (a), (b) and (c) above along with loss due to surface wave phenomenon

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Transistor T₁ operates at 30 kHz and T₂ operates at 300 Hz. The flicker noise is

not depend on frequency

T₁ > T₂

T₁ = T₂

T₁ < T₂

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A pre-emphasis circuit provides extra noise immunity by

converting the phase modulation to frequency modulation

pre-amplifying the whole audio band

boosting the base frequencies

amplifying the higher audio frequencies

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A tape recorder and deck are entirely similar.

True

False

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The antenna current of an AM transmitter is 8 A. When only the carrier is sent, but it increases to 8.93 A. When the carrier is sinusoidally modulated. The percentage modulation is nearly

90%

80%

75%

70%

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Assertion (A): SSB systems generally have duplex operation

Reason (R): SSB systems are generally used in two way communication.

Both A and R are correct and R is correct explanation of A

Both A and R are correct but R is not correct explanation of A

A is correct but R is wrong

A is wrong but R is correct