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ECE :: Communication Systems

  1. If the oscillator output is modulated by audio frequencies upto 10 kHz, the frequency range occupied by the side bands will be

  2. A.
    711.9 kHz to 712.1 kHz
    B.
    702 kHz to 722 kHz
    C.
    692 kHz to 732 kHz
    D.
    71.2 kHz to 71.20 kHz

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  3. The power to the portable unit of a cordless telephone is provided by

  4. A.
    pencil cells
    B.
    dry cells
    C.
    rechargeable cells
    D.
    AC mains

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  5. In a AM wave the carrier and one of the side bands is suppressed. If m = 0.5, the percentage saving in power is

  6. A.
    50%
    B.
    83.3%
    C.
    94.4%
    D.
    100%

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  7. Computer communication networks have

  8. A.
    star configuration
    B.
    tree configuration
    C.
    loop/mesh configuration
    D.
    All of the above

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  9. Assertion (A): A balun is an RF impedance matching transformer.

    Reason (R): Sometimes a booster amplifier is used with a TV set.

  10. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    A is wrong but R is correct

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  11. In an FM system, when the AF is 500 Hz and the AF voltage is 2.4 V, the deviation is 4.8 kHz. If the AF voltage is now increased to 7.2 V, the new deviation will be

  12. A.
    4.8 kHz
    B.
    9.6 kHz
    C.
    14.4 kHz
    D.
    28.8 kHz

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  13. Modulation is also called detection.

  14. A.
    True
    B.
    False

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  15. The maximum range of a transmitter depends on

  16. A.
    its frequency
    B.
    its power
    C.
    both its frequency and power
    D.
    none of the above

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  17. Consider the following statements about Yagi Uda antenna

    1. It is unidirectional
    2. Its gain is about 7 dB
    3. It is used at VLF
    4. The optimum separation is 0.11
    Which of the above are correct?

  18. A.
    1 and 2 only
    B.
    1, 2, 4 only
    C.
    1, 2, 3, 4
    D.
    1 and 4 only

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  19. In a two stage cascade amplifier, each stage has a gain of 10 dB and noise figure of 10 dB. The overall noise factor is

  20. A.
    10
    B.
    1.09
    C.
    1
    D.
    10.9

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