Communication Systems

1

If fm is the modulation frequency in FM, the modulation index is proportional to

  1. fm
  2. 1/fm2
  3. fm2
  4. 1/fm
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2

What should be the minimum length of the antenna capable of emitting audio signal of wavelength λ?

  1. λ
  2. λ/2
  3. λ/4
  4. λ/8
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3

If the band width is 1.6 x 1012 Hz, how many communication channels can be obtained with 16 KHz band width radio signal?

  1. 108
  2. 1011
  3. 1010
  4. 1015
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4

An insulator used in a transmission line has dielectric constant equal to 0.25. What is the velocity factor of the transmission line?

  1. 2
  2. 4
  3. 4/3
  4. 3/4
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5

A T.V. tower has a height 200 m. By how much the height of tower be increased to triple its coverage range?

  1. 1800 m
  2. 1600 m
  3. 800 m
  4. 600 m
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6

A radar has a power of 1 Kw and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth = 6.4 x 106 m) is

  1. 80 km
  2. 64 km
  3. 40 km
  4. 16 km
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