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Bihar Board Class 12 (Science) Communication Systems — practice questions — page 3

Explore 65 free Communication Systems questions in Bihar Board Class 12 (Science) Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Communication Systems questions and exercises with answers

Showing questions 61–65 of 65.

What does near-vertical-incidence skywave (NVIS) enable?Read the answer and worked solution →Repeated skipping of a signal between Earth and ionosphere is calledRead the answer and worked solution →Before transmission the transmitter modifies the electric signal forRead the answer and worked solution →An automatic call distributor does what?Read the answer and worked solution →In plate modulation, audio power needed is what share of RF carrier power?Read the answer and worked solution →

Worked practice questions

What does near-vertical-incidence skywave (NVIS) enable?

  1. Satellite uplinks only
  2. Underwater sonar links
  3. Local and regional links
  4. Global broadcasting
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Correct answer: C. Local and regional links

Near-vertical waves return to the ground over a wide area, so they serve communication within several hundred miles.

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Repeated skipping of a signal between Earth and ionosphere is called

  1. Multi-hop propagation
  2. Space-wave fading
  3. Direct ground wave
  4. Line-of-sight path
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Correct answer: A. Multi-hop propagation

A signal that bounces between the ground and the ionosphere more than once travels by multi-hop propagation.

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Before transmission the transmitter modifies the electric signal for

  1. deleting the signal
  2. efficient transmission
  3. audio playback only
  4. adding extra noise
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Correct answer: B. efficient transmission

The transmitter circuit processes the electric signal, for example by modulating and amplifying it, so it can be sent efficiently.

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