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ECE :: Communication Systems

  1. Which of following digital modulation technique?

  2. A.
    ASK
    B.
    FSK
    C.
    PSK
    D.
    All

  3. A discrete zero memory information source has 40 symbols and each symbol is equally likely. The minimum number of bits required to code the source with uniform length code and entropy of the source are

  4. A.
    5 and 5.03
    B.
    6 and 5.83
    C.
    5 and 6.64
    D.
    6 and 5.32

  5. The standard intermediate frequency for FM ratio is

  6. A.
    10.7 MHz
    B.
    4.5 MHz
    C.
    75 kHz
    D.
    455 kHz

  7. In an end fire array, the radiation pattern

  8. A.
    is in the plane of array
    B.
    is at right angles to array
    C.
    is at an angle to the plane of array
    D.
    either (b) or (c)

  9. Armstrong FM transmitter uses

  10. A.
    LC oscillator
    B.
    crystal oscillator
    C.
    RC oscillator
    D.
    either (a) or (c)

  11. An antenna having a length of and grounded at one end is called

  12. A.
    Marconi antenna
    B.
    Yagi antenna
    C.
    Turnstile antenna
    D.
    None of the above

  13. The noise figure of individual stages of a two stage amplifier is 2.03 and 1.54 respectively. If gain of first stage is 62, the overall noise figure is

  14. A.
    2.03
    B.
    2.055
    C.
    3.05
    D.
    6.05

  15. In figure (A) and (B)

  16. A.
    A represents PCM and B represents AM
    B.
    A represents FM and B represents AM
    C.
    A represents AM and B represents FM
    D.
    A represents PCM and B represents FM

  17. A trinitron colour picture tube uses

  18. A.
    three electron guns
    B.
    one electron gun
    C.
    one electron gun with three separate in line cathodes
    D.
    none of the above

  19. For a three stage cascaded amplifier, having gains of G1, G2 and G3 and noise figures of F1, F2, F3 the overall noise figure

  20. A.
    B.
    C.
    D.
    None of the above