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ECE :: Communication Systems

  1. Which of the following is true in a tape recorder?

  2. A.
    Vow is due to variation in motor speed but flutter is due to some other reason
    B.
    Both vow and flutter are due to variations in motor speed
    C.
    Flutter is due to variation in motor speed but vow is due to some other reason
    D.
    Neither vow nor flutter is due to variation in motor speed

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  3. In a high speed modem the data rate handled is about

  4. A.
    1000 bps
    B.
    5000 bps
    C.
    20000 bps
    D.
    50000 bps

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  5. Trinitron is a monochrome picture tube.

  6. A.
    True
    B.
    False

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  7. The first pulse in a TV remote control is

  8. A.
    start pulse
    B.
    preliminary pulse
    C.
    either start pulse or preliminary pulse
    D.
    erase pulse

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  9. If the ratio of ac to dc load impedance of a diode detector is low, the result will be

  10. A.
    poor AGC operation
    B.
    poor AF response
    C.
    negative peak clipping
    D.
    diagonal clipping

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  11. The minimum step size required for a Delta modulator operating at 36 samples/sec to track the signal (here u(t) is the unit step function) x(t) = 125t (u(t) - u(t - 1)) + (250 - 125t) (u(t - 1) - u(t - 2)) So that slope overload is avoided, would be

  12. A.
    2-10
    B.
    2-8
    C.
    2-6
    D.
    2-4

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  13. An FM signal with a deviation δ is passed through a mixer, and has its frequency reduced 5 fold. The deviation in the output of the mixer is

  14. A.
    5/δ
    B.
    Intermediate
    C.
    δ/5
    D.
    δ

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  15. In PCM, if the number of quantization levels is increased from 4 to 64, then the bandwidth requirement will approximately be increased __________ times.

  16. A.
    8
    B.
    16
    C.
    3
    D.
    32

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  17. A tweeter should be fed from the input through a

  18. A.
    low pass filter
    B.
    high pass filter
    C.
    band pass filter
    D.
    band stop filter

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  19. The modulation index is, if fm = 500 Hz, Δf = 2.25 kHz

  20. A.
    2.25
    B.
    4.5
    C.
    9
    D.
    18

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