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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. An antenna has a resistance of 50 Ω and an equivalent noise resistance of 30 Ω The noise figure in decibels is

    2. A.
    1.6 dB
    B.
    2 dB
    C.
    3.6 dB
    D.
    6 dB

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  2. An MTI radar operating at 5 GHz has a PRF of 800 pps. The lowest blind speed is

    3. A.
    48 m/s
    B.
    96 m/s
    C.
    192 m/s
    D.
    24 m/s

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  3. For maximum output the width of air gap of audio head should be

    4. A.
    equal to wavelength
    B.
    half the wavelength
    C.
    one quarter the wavelength
    D.
    very small as compared to wavelength

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  4. The simplest mixer circuit for public address system uses

    5. A.
    fixed resistances
    B.
    variable resistances
    C.
    inductances
    D.
    capacitances

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  5. PAM stands for

    6. A.
    Phase Angle Modulation
    B.
    Phase Amplitude Modulation
    C.
    Pulse Amplitude Modulation
    D.
    Pulse Angle Modulation

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  6. In a perfect conductor the resistor noise is

    7. A.
    maximum
    B.
    zero
    C.
    very high
    D.
    almost infinite

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  7. An RF carrier of 12 kV at 1 MHz is amplitude modulated by 1 kHz signal having peak value of 6 kV. The modulation pattern is seen on CRO screen. The voltage indicated will be

    8. A.
    18 kV
    B.
    1.001 kV
    C.
    6 kV
    D.
    36 kV

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  8. In push pull amplifier, each transistor conducts for

    9. A.
    180°
    B.
    360°
    C.
    90°
    D.
    45°

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  9. In the television system in India, each channel is allowed a bandwidth of

    10. A.
    20 MHz
    B.
    12 MHz
    C.
    7 MHz
    D.
    3 MHz

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  10. A diode detector load consists of 0.01 μF capacitor in parallel with a 5 k ohms resistor. The maximum depth of modulation without diagonal clipping at modulating frequency of 1000 Hz and 10 kHz is

    11. A.
    0.76, 0.24
    B.
    0.95, 0.3
    C.
    0.24, 076
    D.
    0.3, 0.95

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