Home / ECE / Communication Systems :: Section 19

ECE :: Communication Systems

  1. In a pulsed RADAR, the transmitter is connected to the antenna

  2. A.
    during pulse interval
    B.
    during interval between pulses
    C.
    all the time
    D.
    only during a fraction of pulse interval

  3. In a CD, the depth and width of each pit is

  4. A.
    0.5 μm each
    B.
    0.5 μm and 1 mm respectively
    C.
    1 μm and 0.5 mm respectively
    D.
    1 μm each

  5. Which type of modulator amplifier is used in AM transmitter?

  6. A.
    Class A
    B.
    Class B
    C.
    Classes AB
    D.
    Class C with negative feedback

  7. A frequency multiplier stage should operate as

  8. A.
    class A
    B.
    class B
    C.
    class AB
    D.
    class C

  9. A digital watch contains

  10. A.
    quartz crystal oscillator
    B.
    RC oscillator
    C.
    LC oscillator
    D.
    either quartz or RC oscillator

  11. In AM increased depth of modulation increases __________ and in FM with increased depth of modulation __________ increases.

  12. A.
    total transmitted power, bandwidth
    B.
    bandwidth, bandwidth
    C.
    bandwidth, total transmitted power
    D.
    total transmitted power, sideband power

  13. In a DM system, the granular noise occurs when modulating signal

  14. A.
    decrease Rapidly
    B.
    increase
    C.
    has high frequency component
    D.
    change within step size

  15. The figure shows a simple detector circuit for amplitude modulated wave v(t) = (1 + m cos ωmt) cost ωct. If the detector is to follow the envelope of modulated wave at all times the extent of modulation m must be less than or equal to m0 where m0 is given by equation


  16. Huffman code is also known as redundancy code

  17. A.
    True
    B.
    false
    C.
    in some cases
    D.
    depend upon efficiency

  18. If each frequency component of f(t) is shifted by p/2, the resulting signal is

  19. A.
    Hilbert transform of f(t)
    B.
    Inverse Hilbert transform of f(t)
    C.
    Laplace transform of f(t)
    D.
    Fourier transform of f(t)