Important Questions of Communication Systems Physics | Zigya

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11.

Speech signals is in the range of

  • 3700 Hz to 7000 A wavelength

  • 20 Hz to 20 kHz frequency

  • 300 Hz to 3100 Hz frequency

  • 540 kHz to 1600 kHz frequency


12.

To transmit a signal of frequency ωm with a carrier frequency ωc, in AM transmission, the bandwidth of the filter and amplifier is

  • ωm

  • m

  • ωc

  • ωc − ωm


13.

If the height of TV tower is increased by 21%, then the transmission range is enhanced by

  • 10 %

  • 5 %

  • 15 %

  • 25 %


14.

The range of a communication system can be extended by a

  • modulator

  • transmitter

  • repeater

  • receiver


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15.

For commercial telephonic communication, the frequency  range for speech signals is

  • 50 Hz to 1000 Hz

  • 3000 Hz to 4500 Hz

  • 300 Hz to 3100 Hz

  • 5000 Hz to 6500 Hz


16.

The role of envelope detector in an AM receiver is to

  • retrieve the message signal

  • rectify the AM signal

  • modify the AM signal

  • modulate the message signal


17.

Identify the mismatched pair

  • Noise  —  Unwanted signals

  • Repeater  —  Communication satellite

  • Attenuation  —  Srengthening of signal

  • Demodulation  —  Retrieval of information 


18.

Pick out the wrong statement.

  • Analog signals provide a continuous set of values

  • Digital signals represent values as discrete steps

  • Analog signals utilise the binary system

  • Digital signals can be processed by logic gates


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19.

A ground receiver receives a signal at 5 MHz, transmitted by a ground transmitter at a height of 320 m, which is 110 km away from it. Then it can communicate through (radius of the Earth, R = 6400 km)

  • space waves

  • ground waves

  • sky waves

  • both sky and ground waves


20.

The power radiated by a linear antenna of length l at wavelength λ is

  • directly proportional to l

  • inversely proportional to λ

  • inversely proportional to λ2

  • directly proportional to λ2


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