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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. Brownian motion is

    2. A.
    random emission of electrons in vacuum tubes
    B.
    thermal motion of electrons in a resistance
    C.
    random diffusion of holes and electrons in semi- conductors
    D.
    both (b) and (c)

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  2. In a TV studio the illuminance is about

    3. A.
    200 lux
    B.
    1000 lux
    C.
    10000 lux
    D.
    10 lux

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  3. MEWS stands for

    4. A.
    Missile Early Warning System
    B.
    Moving Target Early warning System
    C.
    Missile Early Warning Signal
    D.
    Moving Target Early Warning Signal

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  4. Top loading in an antenna increases

    5. A.
    effective height
    B.
    beam width
    C.
    input capacitance
    D.
    bandwidth

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  5. In a radar, the return echo arrives after the allocated pulse interval. Then

    6. A.
    the receiver may be over loaded
    B.
    the target will appear closer than its actual position
    C.
    the return echo may interfere with transmitter operation
    D.
    none of the above

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  6. The decoder for PAL system is

    7. A.
    similar to NTSC decoder
    B.
    similar to NTSC decoder supplemented by 64 ms delay line
    C.
    similar to NTSC decoder supplemented by 64 ms delay line and an electronic commutator
    D.
    either (b) or (c)

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  7. CW Doppler radar is capable of giving accurate measurements of relative velocities.

    8. A.
    True
    B.
    False

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  8. In the stabilized reactance modulators AFC system

    9. A.
    the discriminator must have a fast time constant to prevent demodulation
    B.
    the higher discriminator frequency the better the oscillator frequency stability
    C.
    the discriminator frequency must not be too low, or the system will fail
    D.
    phase modulation is converted into FM by the equalizer circuit

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  9. An antenna is 30 metre high. The frequency is 1 MHz. The radiation resistance is about

    10. A.
    1500 Ω
    B.
    150 Ω
    C.
    15 Ω
    D.
    1.5 Ω

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  10. Which of the following codes is based on BCD format?

    11. A.
    EBCDIC
    B.
    ASCII
    C.
    Hollerith
    D.
    both (a) and (b)

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