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ECE :: Communication Systems

  1. FSK is a system involving

  2. A.
    pulse modulation
    B.
    frequency modulation
    C.
    amplitude modulation
    D.
    phase modulation

  3. A 200 Hz sound wave is to be transmitted by a 1000 kHz radio wave using frequency modulation. The instantaneous frequency variation will be

  4. A.
    100 times a second
    B.
    200 times a second
    C.
    400 times a second
    D.
    1000 times a second

  5. In a TV studios, flying spot scanner is a device for

  6. A.
    mixing video and audio signals
    B.
    telecasting feature films
    C.
    live telecast of outdoor programs
    D.
    telecast of indoor music programs

  7. A broadcast radio transmitter radiates 5 kW when the modulation percentage is 60. How much of this is carrier power?

  8. A.
    6.66 kW
    B.
    5 kW
    C.
    4.9 kW
    D.
    4.23 kW

  9. A device has two resistances 300 Ω and 200 Ω respectively. The noise voltages due to these two resistance calculated separately are 5.38 μV and 4.38 μV respectively. When both of them are used together, the noise voltage will be

  10. A.
    9.76 V
    B.
    1 μV
    C.
    23.56 μV
    D.
    6.94 μV

  11. The antenna diameter of a radar system is doubled. The maximum range will

  12. A.
    be doubled
    B.
    become four times
    C.
    be halved
    D.
    decrease to one fourth

  13. Which of the following microphones works on the piezoelectric effect?

  14. A.
    Carbon
    B.
    Condenser
    C.
    Moving coil
    D.
    Crystal

  15. In PAL system weighting of R - Y and B - Y signals is done to

  16. A.
    prevent over modulation on saturated colours
    B.
    prevent under modulation of saturated colours
    C.
    allow over modulation of saturated colours
    D.
    allow under modulation on saturated colours

  17. In case of probability of the message is 1 to 16 then the information will be

  18. A.
    16 bits
    B.
    8 bits
    C.
    4 bits
    D.
    2 bits

  19. The saving of power in DSB-SC modulated at 80% is

  20. A.
    NIL
    B.
    80%
    C.
    75.76%
    D.
    50%