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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. LCD uses

    2. A.
    nematic crystals
    B.
    sematic crystals
    C.
    cholesteric crystals
    D.
    twisted nematic crystal

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  2. Which of the following stage is not present in AM receiver as compared to FM receiver?

    3. A.
    AM amplifier
    B.
    Demodulator
    C.
    Amplitude limiter
    D.
    AF amplitude

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  3. The function of duplexer in a RADAR is

    4. A.
    to permit the use of same antenna for transmission and reception
    B.
    to provide gain to the transmitted power
    C.
    to amplify the received signal
    D.
    both (b) and (c)

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  4. If e = 10 cos (2p x 108t + 20 cos 2p 103t). The bandwidth is

    5. A.
    108 Hz
    B.
    42 kHz
    C.
    21 kHz
    D.
    108 ± 103 Hz

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  5. In FM, as the modulating frequency decreases and the modulating voltage amplitude

    6. A.
    increases, the modulation index increases
    B.
    decrease, the modulation index increases
    C.
    remains constant, the modulation index increases
    D.
    remains constant, the modulation index decreases

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  6. Modulation system used for video-modulation in television broadcast is

    7. A.
    SSB AM with carrier
    B.
    SSB with carrier suppressed
    C.
    DSB AM with carrier
    D.
    a modified form of SSB with carrier called vestigial sideband

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  7. The highest modulation frequencies typically used in FM broadcast is

    8. A.
    5 kHz
    B.
    10 kHz
    C.
    15 kHz
    D.
    25 kHz

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  8. The intermediate frequency of a superheterodyne receiver is 450 kHz. If it is tuned to 1200 kHz, the image frequency will be

    9. A.
    750 kHz
    B.
    900 kHz
    C.
    1600 kHz
    D.
    2100 kHz

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  9. In the above case the modulation index will be

    10. A.
    9.6
    B.
    28.8
    C.
    57.6
    D.
    100

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  10. Which of the following statement regarding single-sideband (SSB) transmission is not correct?

    11. A.
    In such transmission only or sideband is transmitted, leaving of the other sideband and the carrier
    B.
    It has gained general acceptance of use in home-entertainment equipment
    C.
    It is generally reserved for point-to-point communication
    D.
    The amount of power and bandwidth necessary to be transmitted for a given amount of information are appreciable reduced

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