Communication Systems - ECE Questions and Answers

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Circular polarization

Is useful in reducing depolarization effect on received wave

Involves critical alignment of transmitting and receiving antenna

Is useful in discrimination between reception of adjacent beams

None of the above

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If in a broadcasting studio, a 1000 kHz carrier is modulated by an audio signal of frequency range 100-5000 kHz, the width of channel is __________ kHz.

4.9

995

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In Modulation, “carrier” is

Resultant wave

Speech voltage to be transmitted

Voltage with constant frequency, phase or amplitude

Voltage for which frequency, phase or amplitude is varied

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For a plate-modulated class C amplifier the plate supply voltage is E. The maximum plate cathode voltage could be almost high as

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A cordless telephone using separate frequencies for transmission in base and portable units is known as

Duplex arrangement

Half duplex arrangement

Either A or B

Neither A nor B

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In TV systems, equalising pulses are sent during

Horizontal blanking

Vertical blanking

Serrations

Horizontal retrace

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For a given carrier wave, maximum undistorted power is transmitted when value of modulation is

0.8

0.5

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The modulation index of an FM is changed from 0 to 1. How does the transmitted power change?

Gets halved

Gets doubled

Gets increased by 50 percent

Remains unchanged

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The maximum power output of a standard A earth station over the total band allocated to satellite communication is about

0.5 kW

8 kW

20 kW

50 kW