Communication miscellaneous

Communication miscellaneous

Easy Questions
Moderate Questions
Difficult Questions

Communication

Communication miscellaneous
  1. Amplitude modulation is used for broadcasting because—








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    NA

    Correct Option: C

    NA

  1. The positive RF peaks of an AM voltage rise to a maximum value of 12 V and drop to a minimum value of 4V. The modulation index assuming single tone modulation is—








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    Given,
    Emax = 12V, Emin = 4V

    μ =
    Emax − Emin
    Emax + Emin


    μ =
    12 − 4
    		 =
    8
    		 =
    1
    12 + 4 16 2

    Correct Option: D

    Given,
    Emax = 12V, Emin = 4V

    μ =
    Emax − Emin
    Emax + Emin


    μ =
    12 − 4
    		 =
    8
    		 =
    1
    12 + 4 16 2

  1. The most suitable method for detecting a modulated signal (2·5 + 5 cos ωmt) cos ωmt is—








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    Given modulated signal
    s(t) = (2·5 + 5 cos ωmt) cos ωc t
    or
    s(t) = 2·5 (1 + 2 cos ωmt) cos ωct
    Since here modulation index, μ = 2 > 1. Hence signal can’t be detected by envelop detector and synchronous detector.
    Hence alternative (B) is the correct choice.

    Correct Option: B

    Given modulated signal
    s(t) = (2·5 + 5 cos ωmt) cos ωc t
    or
    s(t) = 2·5 (1 + 2 cos ωmt) cos ωct
    Since here modulation index, μ = 2 > 1. Hence signal can’t be detected by envelop detector and synchronous detector.
    Hence alternative (B) is the correct choice.

  1. In the above question, the total bandwidth required to transmit the AM wave is—








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    Total bandwidth,
    BW = 2fm = 2 × 1500 = 3000 = 3 kHz

    Correct Option: B

    Total bandwidth,
    BW = 2fm = 2 × 1500 = 3000 = 3 kHz

  1. A linear phase channel with phase delay τp and group delay τg must have—








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    For a linear phase channel both phase delay τp and group delay τg should be constant.

    Correct Option: A

    For a linear phase channel both phase delay τp and group delay τg should be constant.