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ECE :: Communication Systems

  1. Which of the following is the main advantage of PCM system?

  2. A.
    Lower noise
    B.
    Lower power
    C.
    Lower bandwidth
    D.
    All of the above

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  3. BPSK stands for

  4. A.
    Binary Phase Shifting Key
    B.
    Broad Phase Shifting Key
    C.
    Bit Phase Shifting Key
    D.
    Binary Pulse Shifting Key

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  5. If a dipole is meant for a frequency of 1 MHz, the length of each rod is about

  6. A.
    5 m
    B.
    20 m
    C.
    100 m
    D.
    50 m

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  7. Consider the following statements:
    In a radar system having a high value of the ratio (antenna diameter)/wavelength

    1. the maximum range is large
    2. good target discrimination is achieved
    3. capture area is increased
    4. target acquisition is difficult
    Which of the above are correct?

  8. A.
    1, 2, 3, 4
    B.
    1, 2, 3
    C.
    1, 2
    D.
    1, 3, 4

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  9. Assertion (A): The maximum range of a radar is proportional to fourth root of the peak transmitted pulse power.

    Reason (R): Radar signals are subjected twice to inverse square law.

  10. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    A is wrong but R is correct

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  11. As EM waves travel in free space they get

  12. A.
    reflected
    B.
    refracted
    C.
    attenuated
    D.
    absorbed

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  13. Cross talk is due to reception of portions of a signal from one channel into another.

  14. A.
    True
    B.
    False

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  15. If there are M equally likely and independent messages and M = 2N where N is an integer, the information in each message is equal to

  16. A.
    N bits
    B.
    0.5 N bits
    C.
    2 N bits
    D.
    4 N bits

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  17. A radar beacon is a small radar set having a receiver, a separate transmitter and an antenna.

  18. A.
    True
    B.
    False

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  19. In the above case the total power in the modulated wave double sideband, suppressed carrier AM will be

  20. A.
    112 W
    B.
    400 W
    C.
    415 W
    D.
    512 W

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