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What is modulation and why it is needed ...

What is modulation and why it is needed ?

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Modulation is the process by which some characteristics of a relatively high frequency wave is varied in accordance with the instantaneous value of a low frequency.
Need for modulation For transmission of signal, the height of antenna should be comparable to the wavelength of signal. For audio signal, the height of antenna should be from `15 km` to `15000km`, which is not possible, hence modulation of signal is required.
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MBD -HARYANA BOARD-PRINCIPLES OF COMMUNICATION-Objective Type Questions
  1. What is modulation and why it is needed ?

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  2. The sky wave propagation is suitable for radiowaves of frequency

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  3. Ozone layer is present in

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  4. INSAT-IA satellite is used for :

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  5. A TV tower of height h can broadcast program upto a distance ( given r...

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  6. In UHF range the frequencies are propagated by means of :

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  7. The diameter of an optical fibre is :

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  8. In the process of modulation, the radio frequency wave is known as

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  9. Ozone layer in atmosphere is useful because it :

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  10. The height of a T.V. tower is 100m. If radius of earth is 6400km, then...

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  11. The most commonly used system of modulation for telegraphy is :

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  12. Ionosphere can reflect which type of waves ?

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  13. For television transmission, the frequency employed is normally in the...

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  14. The electromagnetic waves used in the telecommunication are

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  15. the attenution in optical fibre is mainly due to

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  16. The output from a LASER is monochromatic. It means that it is :

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  17. Radio waves of frequency 300MHz-3000MHz belongs to :

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  18. A TV tower has a height of 100m. By how much the height of tower be in...

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  19. Radio waves of constant amplitude can be generated with:

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  20. Radio waves are reflected from which layer of atmosphere ?

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