COMMUNICATION SYSTEMS QUIZ

In a FM receiver, amplitude limiter

Eliminates any change in amplitude of received FM signals

Reduces the amplitude of signals

Amplifiers low frequency signals

None of these

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For telegraphy the most commonly used modulation system is

Single tone modulation

FSK

PCM

Two tone modulation

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

Gets increased by 50 percent

Gets halved

Gets doubled

Remains unchanged

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In case of low level amplitude modulation system, the amplifiers following the modulated stage must be

Non-linear devices

Linear devices

Harmonic devices

Class C amplifiers

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In case of frequency modulation, modulating voltage remains constant if the modulating frequency is lowered, then

Amplitude of distant sidebands increases

Amplitude of distant sidebands first increases, then decreases

Amplitude of distant sidebands decreases

Amplitude of distant sidebands remains constant

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FM transmitting and receiving equipment as compared to AM equipment is

Almost equally costly

None of these

Cheaper

Costly

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For attenuation of high frequencies we should use

Resistance

Series capacitance

Shunt capacitance

Inductance

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Which of the following does not cause losses in optical fibre cables?

Stepped index operation

Attenuation in glass

Microbending

Impurities

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The disadvantage of FM over AM is that

Noise is very high for high frequency

High output power is needed

High modulating power is needed

Large bandwidth is required

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Which one of the following is analog?

Differential PCM

Delta modulation

PWM

PCM

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