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ECE :: Communication Systems

  1. A line has L = 0.8 µH/m and C = 32 pF/m. Z0 =

  2. A.
    6000
    B.
    600
    C.
    158
    D.
    15.8

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  3. A line has standing waves with a voltage maximum of 35 mV and minimum of 17.5 mV VSWR is

  4. A.
    2
    B.
    4
    C.
    0.5
    D.
    0.25

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  5. For a bit rate of 8 kbps, the best possible values of the transmitted frequencies in a coherent binary FSK system are

  6. A.
    16 kHz and 20 kHz
    B.
    20 kHz and 32 kHz
    C.
    20 kHz and 40 kHz
    D.
    32 kHz and 40 kHz

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  7. If luminance signal Y = 0.3 R + 0.59 G + 0.11 B, the hue of R - Y colour is

  8. A.
    0.7 R - 0.59 G - 0.11 B
    B.
    - 0.7 R + 0.59 G + 0.11 B
    C.
    1.3 R - 0.59 G - 0.11 B
    D.
    none of the above

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  9. Trap circuits used in video IF amplifier of colour TV are

  10. A.
    High Q, LC resonant circuit
    B.
    Low Q, LC resonant circuit
    C.
    High Q, RLC resonant circuit
    D.
    Low Q, RLC resonant circuit

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  11. A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. Which of the following frequency is least likely to be present in the output?

  12. A.
    1002 kHz
    B.
    1000 kHz
    C.
    999.2 kHz
    D.
    998.0 kHz

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  13. A 300 Hz sound wave of intensity 20 dB is transmitted by a 1500 kHz radio wave by frequency modulation. It is seen that instantaneous frequency varies between 1500.2 kHz and 1499.8 kHz, 300 times a second. If the intensity of sound wave is 100 dB.

  14. A.
    The instantaneous frequency variations will be between 1500.2 and 1499.8 kHz, 1500 times a second
    B.
    The instantaneous frequency variations will be between 1501 and 1499 kHz, 1500 times a second
    C.
    The instantaneous frequency variations will be between 1501 and 1499 kHz, 300 times a second
    D.
    The instantaneous frequency variations will be between 1501 and 1499 kHz, 60 times a second

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  15. If the average power of radar transmitters is 2 kW and the peak power of the transmitter is 1000 kW, what will be the duty cycle?

  16. A.
    0.002
    B.
    0.02
    C.
    0.001
    D.
    0.01

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  17. An analog signal is band limited to B Hz sampled at Nyquist rate and samples are quantized into 4 levels each with probability . The information rate is

  18. A.
    4 bits/s
    B.
    B bits/s
    C.
    4 B bits/s
    D.
    0.25 B bits/s

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  19. The HV supply to a TV receiver is 25 kV and the total beam current for the three electron guns is 2000 μA. The power handled by IHVT is

  20. A.
    5W
    B.
    0.5 W
    C.
    50 W
    D.
    500 W

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