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ECE :: Communication Systems

  1. The output resistance of a microphone is 20 ohms. It is to feed a line of impedance 320 ohms. To ensure maximum power transfer, the turn ratio of transformer is

  2. A.
    16
    B.
    256
    C.
    2
    D.
    4

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  3. In a reactance FET, gm = 9 x 10-3 Siemens, gate to source resistance is one-ninth of reactance of gate to drain capacitor and frequency is 4 MHz. The capacitive-reactance is

  4. A.
    1000 Ω
    B.
    1/1000 Ω
    C.
    36 x 103 Ω
    D.
    x 103 Ω

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  5. Audio cassettes used in household tape recorders have a width of

  6. A.
    1"
    B.
    1/2"
    C.
    1/4"
    D.
    1/8"

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  7. The receiver of a pulsed RADAR can detect signal power in the order of

  8. A.
    1 W
    B.
    0.1 W
    C.
    10-5 W
    D.
    10-12 W

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  9. In a 100% amplitude modulated signal, the power in the upper sideband when carrier power is to be 100 W and modulation system SSBSC, is

  10. A.
    100 W
    B.
    66 W
    C.
    50 W
    D.
    25 W

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  11. Which camera tube has highest dark current?

  12. A.
    Plumbicon
    B.
    Vidicon
    C.
    Saticon
    D.
    GCD imager

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  13. If a sound wave has a frequency of 50 Hz, the wavelength is

  14. A.
    66 m
    B.
    6.6 m
    C.
    0.66 m
    D.
    0.066 m

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  15. Skin depth at 1000 MHz in comparison with that at 500 MHz is

  16. A.
    2
    B.
    2
    C.
    D.
    1/2

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  17. Consider the following

    1. Generation of SSB signals
    2. Design of minimum phase type filters
    3. Representation of band pass signals
    Which of the above applications is Hilbert transform used?

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

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  19. The dc voltage on plate modulated class C amplifier is 8 kV. If the peak modulating voltage is 4 kV, the peak RF voltage delivered to load is

  20. A.
    32 kV
    B.
    12 kV
    C.
    0.5 kV
    D.
    24 kV

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