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ECE :: Communication Systems

  1. The main advantage of superheterodyne receiver is

  2. A.
    better tracking
    B.
    simple cut
    C.
    better alignment
    D.
    improvement in selectivity and sensitivity

  3. PAL system was proposed first in

  4. A.
    USA
    B.
    Japan
    C.
    England
    D.
    Germany

  5. MCVF telegraphy causes

  6. A.
    SSB techniques
    B.
    pulse modulation
    C.
    Out of bond signalling
    D.
    FM

  7. Consider the following statements as regards noise

    1. If Gaussian noise is applied at input of a rectifier, the output is not gaussian
    2. The noise encountered on a telephone line consists of short, pulse type disturbances whose amplitude distribution is not Gaussian
    3. Shot noise results from random emission of electrons from a cathode
    4. Shot noise results from phenomenon associated with the flow of current across semi conductor junctions
    Which of the above are correct?

  8. A.
    1, 2, 3, only
    B.
    1, 2, 4 only
    C.
    1, 2, 3, 4
    D.
    2, 3 only

  9. Noise can be reduced by increasing sampling rate

  10. A.
    true
    B.
    false
    C.
    can't say
    D.
    insufficient data

  11. In tape recorder erase head is active during recording.

  12. A.
    True
    B.
    False

  13. Which of the following microphones has maximum distortion?

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

  15. The relation between bandwidth B, modulating frequency fm and frequency deviation Δf for a sinusoidally modulated FM signal is

  16. A.
    B = Δf + fm
    B.
    B = 2(Δf + fm)
    C.
    B = fm - Δf/
    D.
    B = 2(fm - Δf)

  17. FM broadcast is used in

  18. A.
    VHP range
    B.
    UHF range
    C.
    MF range
    D.
    both VHP and UHF range

  19. The power requirement of a RADAR used in military operations is

  20. A.
    a few watts
    B.
    about 500 W
    C.
    about 2000 W
    D.
    a few megawatts