COMMUNICATION SYSTEMS QUIZ

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

Remains unchanged

Gets halved

Gets increased by 50 percent

Gets doubled

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Which of the following is a digital modulation technique?

PSK

PCM

All

DM

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For AM receivers the standard IF frequency is

106 kHz

455 kHz

1.07 MHz

10.7 MHz

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The characteristic impedance of a twin wire feeder used for TV signals is about

1000 ohm

100 ohm

500 ohm

300 ohm

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To eliminate ghosts in the picture

Change the antenna orientation of location

Use a longer transmission line

Connect a booster

Twist the transmission line

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

Class C amplifiers

Linear devices

Harmonic devices

Non-linear devices

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If output power of a radio receiver is doubled, its volume is increased by __________ dB.

2

-3

3

1

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Which of the following is used to generate PDM?

Free running multi-vibrator

JK flip-flop

Monostable multi-vibrator

Schmitt trigger

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FM transmitting and receiving equipment as compared to AM equipment is

None of these

Almost equally costly

Costly

Cheaper

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An audio signal (say from 50 Hz to 10000 Hz) is frequency translated by a carrier having a frequency of 106 Hz. The values of initial (without frequency translation) and final (after frequency translation) fractional change in frequency from one band edge to the other are

200 and 200

200 and 100.1

200 and 10.01

200 and 1.01

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