Home / ECE / Communication Systems :: Section 25

ECE :: Communication Systems

  1. Which of the following is an indirect way of generating FM?

  2. A.
    Armstrong modulator
    B.
    Varactor diode modulator
    C.
    Reactance FET modulator
    D.
    Reactance bipolar transistor

    View Answer

    Workspace

    Discuss Discuss in Forum


  3. When the length of antenna is a whole wavelength

  4. A.
    the radiation at right angles is zero
    B.
    the radiation at right angles is maximum
    C.
    the radiation is zero in all directions
    D.
    the radiation is maximum in all directions

    View Answer

    Workspace

    Discuss Discuss in Forum


  5. Circular polarization

  6. A.
    is useful in reducing depolarization effect on received wave
    B.
    involves critical alignment of transmitting and receiving antenna
    C.
    is useful in discrimination between reception of adjacent beams
    D.
    none of the above

    View Answer

    Workspace

    Discuss Discuss in Forum


  7. An FM radio receiver which is tuned to a 91.6 MHz broadcast station may receive an image frequency of __________ MHz.

  8. A.
    102.3
    B.
    113
    C.
    70.2
    D.
    80.9

    View Answer

    Workspace

    Discuss Discuss in Forum


  9. If S represents the carrier synchronization at the receiver and r represents the bandwidth efficiency, then the correct statement for the coherent binary PSK is

  10. A.
    r = 0.5, S is required
    B.
    r = 1.0, S is required
    C.
    r = 0.5, S is not required
    D.
    r = 1.0, S is not required

    View Answer

    Workspace

    Discuss Discuss in Forum


  11. For telegraphy the most commonly used modulation system is

  12. A.
    FSK
    B.
    two tone modulation
    C.
    PCM
    D.
    single tone modulation

    View Answer

    Workspace

    Discuss Discuss in Forum


  13. Commercial Frequency deviation of FM is

  14. A.
    70 kHz
    B.
    75 kHz
    C.
    80 kHz
    D.
    65 kHz

    View Answer

    Workspace

    Discuss Discuss in Forum


  15. The colour of an object is decided by

  16. A.
    the reflected colour
    B.
    the wavelength transmitted through it
    C.
    reflected colour for opaque object and wavelength transmitted through it for transparent objects
    D.
    none of the above

    View Answer

    Workspace

    Discuss Discuss in Forum


  17. In Pulse Code Modulation system

  18. A.
    large bandwidth is required
    B.
    quantising noise can be overcome by companding
    C.
    quantising noise can be reduced by decreasing the number of standard levels
    D.
    suffers from the disadvantage of its incompatibly with TDM

    View Answer

    Workspace

    Discuss Discuss in Forum


  19. Waveform shown in figure is that for

  20. A.
    FM
    B.
    PCM
    C.
    AM-DSB
    D.
    AM-SSB

    View Answer

    Workspace

    Discuss Discuss in Forum