Home / ECE / Communication Systems :: Section 22

ECE :: Communication Systems

  1. Which of the following form of angle modulation in this? If e = 10 sin(108 t + 3 sin 104 t)

  2. A.
    AM
    B.
    FM
    C.
    AM or FM
    D.
    AM or PCM

    View Answer

    Workspace

    Discuss Discuss in Forum


  3. The noise performance of a square law demodulator of AM signal is

  4. A.
    better than that of an envelope detector
    B.
    better than that of a synchronous detector
    C.
    identical with that of a synchronous detector
    D.
    poorer than that of an envelope detector

    View Answer

    Workspace

    Discuss Discuss in Forum


  5. In AM the amplitude of carrier components ... while in FM it

  6. A.
    remains constant, does not remain constant
    B.
    does not remain constant ... remains constant
    C.
    remains constant... also remains constant
    D.
    does not remain constant, also does not remain constant

    View Answer

    Workspace

    Discuss Discuss in Forum


  7. In a colour TV receiver, the function of comb filter is

  8. A.
    to pass only the clusters of monochrome signal energy while blocking chrome signals
    B.
    to pass only chrome signals and block monochrome signals
    C.
    to block both monochrome and chrome signals
    D.
    none of the above

    View Answer

    Workspace

    Discuss Discuss in Forum


  9. A communication receiver is

  10. A.
    TRF receiver
    B.
    a superheterodyne receiver
    C.
    either (a) or (b)
    D.
    neither (a) nor (b)

    View Answer

    Workspace

    Discuss Discuss in Forum


  11. In PCM, bit duration is defined as

  12. A.
    B.
    C.
    sampling period x total no. of bits
    D.
    none of these

    View Answer

    Workspace

    Discuss Discuss in Forum


  13. Assertion (A): If frequency is high, the distance between transmitter and antenna may be an appreciable fraction of wavelength

    Reason (R): Wavelength is inversely proportional to frequency.

  14. 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

    View Answer

    Workspace

    Discuss Discuss in Forum


  15. Speeds of sound and radio waves are equal.

  16. A.
    True
    B.
    False

    View Answer

    Workspace

    Discuss Discuss in Forum


  17. When Pc is the unmodulated carrier power and Pt is the total power in the modulated wave, then the maximum power in AM wave is

  18. A.
    Pt = 1.5 Pc
    B.
    Pt = 2.5 Pc
    C.
    Pt = 2
    D.
    Pt = 22 Pc

    View Answer

    Workspace

    Discuss Discuss in Forum


  19. Thermal noise is passed through an ideal low pass filter having cut off at fc = ω Hz. The auto-correlation value of the noise at the output of the filter is given as

  20. A.
    a delta function at t = 0
    B.
    gaussian over the range -∞ ≤ t ≤ ∞
    C.
    sin c function over the range -∞ ≤ t ≤ ∞
    D.
    triangular function over the range

    View Answer

    Workspace

    Discuss Discuss in Forum