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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. The percentage saving in power when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of 100% will be nearly

    2. A.
    50%
    B.
    66%
    C.
    75%
    D.
    83%

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  2. The difference between phase and frequency modulation

    3. A.
    is purely of academic interest
    B.
    lies in the different definitions of the modulation index
    C.
    lies in the poor audio response of phase modulation
    D.
    is too great to make the two systems compatible

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  3. A signal m(t) amplitude modulates a carrier Ac cos ωct. The final signal will be

    4. A.
    [Ac m(t)] cos ωct]
    B.
    Ac . [1 + m(t)] cos ωct
    C.
    Ac + [m(t)] cos ωct
    D.
    Ac cos ωct + m(t)

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  4. An oscillator at 4.2 MHz is followed by two frequency doublers and two triplers. The output frequency will be

    5. A.
    84 MHz
    B.
    112.4 MHz
    C.
    151.2 MHz
    D.
    303.4 MHz

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  5. Over which frequency range the effect of atmospheric noise is significant?

    6. A.
    Over 35 MHz
    B.
    Below 30 MHz
    C.
    Between 30 MHz and 100 MHz
    D.
    Between 100 MHz and 150 MHz

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  6. If B is channel bandwidth, S is signal power and N is the total noise within the channel bandwidth, the channel capacity C of a white band limited gaussian channel is

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  7. An amplifier of passband 450 kHz to 460 kHz will be named as

    8. A.
    video amplifier
    B.
    audio frequency amplifier
    C.
    tuned voltage amplifier
    D.
    wideband amplifier

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  8. Which of the following statement is false?

    9. A.
    A stationary process is always a ergodic process
    B.
    A ergodic process is always a stationary random process
    C.
    It is possible to have a stationary random
    D.
    None of the above

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  9. In amplitude modulation, the magnitude of side bands is

    10. A.
    ma/2 times the carrier amplitude, Ec
    B.
    ma times the carrier amplitude, Ec
    C.
    2ma times the carrier amplitude, Ec
    D.
    4ma times the carrier amplitude, Ec

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  10. For broadcasting purpose, full AM signal is preferred to SSB signal because

    11. A.
    it requires large bandwidth
    B.
    generation of full AM is easier
    C.
    detection of full AM is simpler
    D.
    none of the above

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