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ECE :: Communication Systems

Communication Systems - Section 1
Communication Systems - Section 2
Communication Systems - Section 3
Communication Systems - Section 4
Communication Systems - Section 5
Communication Systems - Section 6
Communication Systems - Section 7
Communication Systems - Section 8
Communication Systems - Section 9
Communication Systems - Section 10
Communication Systems - Section 11
Communication Systems - Section 12
Communication Systems - Section 13
Communication Systems - Section 14
Communication Systems - Section 15
Communication Systems - Section 16
Communication Systems - Section 17
Communication Systems - Section 18
Communication Systems - Section 19
Communication Systems - Section 20
Communication Systems - Section 21
Communication Systems - Section 22
Communication Systems - Section 23
Communication Systems - Section 24
Communication Systems - Section 25
Communication Systems - section-26
Communication Systems - Section-27
  1. For telegraphy the most commonly used modulation system is

    2. A.

     FSK
    B.

     Two tone modulation
    C.

     PCM
    D.

     Single tone modulation

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  2. The main function of a balanced modulator is to

    3. A.

     Produce balanced modulation of a carrier wave
    B.

     Produce 100% modulation
    C.

     Suppress carrier signal in order to create a single-sideband or double sideband
    D.

     Limit noise picked by a receiver

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  3. In case of frequency modulation, modulating voltage remains constant if the modulating frequency is lowered, then

    4. A.

     Amplitude of distant sidebands decreases
    B.

     Amplitude of distant sidebands increases
    C.

     Amplitude of distant sidebands remains constant
    D.

     Amplitude of distant sidebands first increases, then decreases

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  4. Full duplex operation permits transmission in both directions at the same time.

    5. A.

     True
    B.

     False

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  5. The colour of an object is decided by

    6. A.

     The reflected colour
    B.

     The wavelength transmitted through it
    C.

     Reflected colour for opaque object and wavelength transmitted through it for transparent objects
    D.

     None of the above

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  6. Which of the following is a digital modulation technique?

    7. A.

     PCM
    B.

     PSK
    C.

     DM
    D.

     All

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  7. Assertion (A): In FM the frequency of the carrier is varied by the modulating voltage
    Reason (R): FM and PM are two forms of angle modulation.

    8. 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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  8. PAM stands for

    9. A.

     Pulse Analogue Modulation
    B.

     Phase Analogue Modulation
    C.

     Pulse Amplitude Modulation
    D.

     Phase Amplitude Modulation

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  9. Which of the following does not cause losses in optical fibre cables?

    10. A.

     Stepped index operation
    B.

     Impurities
    C.

     Microbending
    D.

     Attenuation in glass

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  10. In a FM receiver, amplitude limiter

    11. A.

     Amplifiers low frequency signals
    B.

     Reduces the amplitude of signals
    C.

     Eliminates any change in amplitude of received FM signals
    D.

     None of the above

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