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ECE :: Communication Systems

  1. A receiver has poor selectivity. It will also have poor

  2. A.
    sensitivity
    B.
    double spotting
    C.
    blocking
    D.
    diversity reception

  3. The depth of modulation is doubled in FM system then, the power transmitted

  4. A.
    increase by factor of 2
    B.
    increase by factor of 3
    C.
    increase by factor of 2
    D.
    none of the above

  5. Ground wave can be used for communication upto

  6. A.
    5 kHz
    B.
    12 kHz
    C.
    16 kHz
    D.
    25 kHz

  7. A Marconi antenna

  8. A.
    is a grounded antenna with a length equal to λ/4
    B.
    is an ungrounded antenna with a length equal to λ/4
    C.
    has a length equal to 1
    D.
    has a length equal to λ/2

  9. When large amount of power is required, a push pull amplifier is designed for operation as

  10. A.
    class A
    B.
    class B
    C.
    class C
    D.
    class AB

  11. In a Vidicon camera tube,

  12. A.
    both sides of the target plate have the coating of tin oxide
    B.
    both sides of the target plate have the coating of antimony tri-sulphide
    C.
    the side of target plate facing the light has a coating of tin oxide and the side facing electron gun has a coating of antimony trisulphide
    D.
    the side of target plate facing the light has a coating of antimony trisulphide while the side facing the electron gun has a coating of tin oxide

  13. The distance at which a sky wave is received back on earth decreases with angle of incidence for all angles of incidence.

  14. A.
    True
    B.
    False

  15. A trigonometric function is synonyms to

  16. A.
    orthogonal function
    B.
    triangular function
    C.
    singular function
    D.
    none of the above

  17. A single tone modulating signal Vm cos ωt modulates a carrier A cos ωct. The carrier power (modulated) and side band powers are respectively


  18. The autocorrelation function of the white noise is

  19. A.
    impulse function
    B.
    step function
    C.
    constant
    D.
    none of the above