Communication Systems - ECE Questions and Answers

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The IF frequencies in a TV receiver

38.9 MHz for video and 33.4 MHz for audio

38.9 MHz for both video and audio

33.4 MHz for both video and audio

33.4 MHz for video and 38.9 MHz for audio

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The most noise resistant modulation system is

PCM

SSB suppressed carrier

pulse position modulation

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Which of the following is the digital system?

PWM

PAM

PPM

PCM

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Which of the following is an oscillator with best frequency stability?

Crystal oscillator

Clapp oscillator

Phase shift circuit

Multivibrator

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In FDM systems used for telephone, which modulation scheme is adopted?

DSB-SC

SSB-SC

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In the above case if another sine wave corresponding to 40% modulation is transmitted simultaneously, the total radiated power will be

9.9 kW

10.15 kW

10.84 kW

18.4 kW

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A pre-emphasis circuit

boosts base frequencies

pre amplifies the complete audio band

amplifies higher audio frequencies

converts FM into phase modulation

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In orthogonal BFSK, the energy of information bearing term is

the same as total transmitted energy

one-half of total transmitted energy

one-fourth of total transmitted energy

none of the above

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In a tape recorder

both record and erase heads have high permeability core

the record head has high permeability core but the erase head has low permeability core

the record head has low permeability core but the erase head has high permeability core

both record and erase heads have low permeability core