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ECE :: Communication Systems

  1. Some multiplexing arrangements for telephone system are

    1. Space multiplexing
    2. Time division multiplexing
    3. Frequency division multiplexing
    Which of the above allow transmission of many independent signals over a single channel?

  2. A.
    1 only
    B.
    2 and 3 only
    C.
    1, 2, 3
    D.
    1 and 3 only

  3. Industrial noise has the frequency range of

  4. A.
    1 to 100 Hz
    B.
    200 to 5000 Hz
    C.
    above 200 MHz
    D.
    1 to 600 MHz

  5. Thermal noise Power is

  6. A.
    proportional to bandwidth (B)
    B.
    ∝ B
    C.
    D.
    ∝B2

  7. The characteristic impedance of coaxial cable is about

  8. A.
    1000 ohm
    B.
    500 ohm
    C.
    250 ohm
    D.
    75 ohm

  9. The diameter and thickness of CD are

  10. A.
    6 cm and 1.2 mm
    B.
    6 cm and 0.6 mm
    C.
    12 cm and 0.6 mm
    D.
    12 cm and 1.2 mm

  11. Consider the following statements about advantages of phase discriminator over slope detector

    1. Fewer tuned circuits
    2. Greater limiting
    3. Better linearity
    4. Easy alignment
    Which of the above are true?

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

  13. In a superheterodyne radio receiver

  14. A.
    RF amplifier normally operates at 455 kHz above carrier frequency
    B.
    mixer input must be tuned to the signal frequency
    C.
    local oscillator operates below signal frequency
    D.
    local oscillator frequency is double the IF

  15. The assigned carrier frequency of an FM broadcast station is 96.3 MHz. Its FM signal has a centre frequency of

  16. A.
    10 MHz
    B.
    455 kHz
    C.
    48.15 MHz
    D.
    96.3 MHz

  17. Digital television is also called

  18. A.
    High digital television
    B.
    High definition television
    C.
    High deflection television
    D.
    High display television

  19. At FM demodulator output noise power density

  20. A.
    increases with frequency
    B.
    decreases with frequency
    C.
    remains unaltered
    D.
    none of the above