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ECE :: Communication Systems

  1. Which of the following circuits cannot be demodulate SSB?

  2. A.
    Product detector
    B.
    Balanced modulator
    C.
    Phase discriminator
    D.
    BFO

  3. Figure shows the arrangement of

  4. A.
    FM
    B.
    PM
    C.
    AM-DSB
    D.
    AM-SSB

  5. During day time ionosphere can be considered to be consisting of

  6. A.
    D, E, F1 and F2 layers
    B.
    D, E, F1 layers
    C.
    D, E, F2 layers
    D.
    D and E layers

  7. Baudot code is a six bit code.

  8. A.
    True
    B.
    False

  9. PWM can be generated

  10. A.
    by a free running multivibrator
    B.
    by integrating the signal
    C.
    by a monostable multivibrator
    D.
    by differentiating pulse position modulation

  11. Which of the following microphones has highest output impedance?

  12. A.
    Carbon
    B.
    Ribbon
    C.
    Crystal
    D.
    Condenser

  13. Consider the following statements about PCM

    1. PCM is not noise resistant
    2. PCM requires complex encoding and quantizing circuitry
    3. PCM requires large bandwidth
    Which of the above are correct?

  14. A.
    1 only
    B.
    1, 2, 3
    C.
    2, 3
    D.
    1 and 3

  15. In a television transmitter, the output stage is most likely to be

  16. A.
    screen modulated class C amplifier
    B.
    plate modulated class C amplifier
    C.
    grid modulated class A amplifier
    D.
    grid modulated class C amplifier

  17. The number of bits of information required to indicate the correct selection of 3 independent consecutive events out of 75 equally probable events is

  18. A.
    6.23
    B.
    18.69
    C.
    10.46
    D.
    24.92

  19. The efficiency of a direct radiating cone type loudspeaker is about

  20. A.
    5%
    B.
    20%
    C.
    50%
    D.
    80%