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EEE :: Modulation and Demodulation

  1. A 50 kW carrier is to be amplitude modulated to a level of 85%. What is the carrier power after modulation?

  2. A.

     50 kW

    B.

     5 kW

    C.

     8 kW

    D.

     25 kW


  3. The major advantage of FM over AM is ___________

  4. A.

     Reception is less noisy

    B.

     Higher carrier frequency

    C.

     Smaller bandwidth

    D.

     Small frequency deviation


  5. In an AM wave, the majority of the power is in ___________

  6. A.

     Lower sideband

    B.

     Upper sideband

    C.

     Carrier

    D.

     None of the above


  7. As the modulation level is increased, the carrier power ___________

  8. A.

     Is increased

    B.

     Remains the same

    C.

     Is decreased

    D.

     None of the above


  9. Modulation refers to a low-frequency signal controlling the ___________

  10. A.

     Amplitude of the carrier

    B.

     Frequency of the carrier

    C.

     Phase of the carrier

    D.

     May be any of the above


  11. In a radio receiver, noise is generally developed at ___________

  12. A.

     IF stage

    B.

     Receiving antenna

    C.

     Audio stage

    D.

     RF stage


  13. The diode detector in an AM radio receiver is usually found ___________

  14. A.

     Before the first RF stage

    B.

     After the first RF stage

    C.

     After several stages of amplification

    D.

     None of the above


  15. The function of ferrite antenna is to ___________

  16. A.

     Reduce stray capacitance

    B.

     Stabilise d.c. bias

    C.

     Increase the Q of tuned circuit

    D.

     Reduce noise


  17. If Amin = 40 and Amax = 60, what is the percentage of modulation?

  18. A.

     20%

    B.

     40%

    C.

     50%

    D.

     10%


  19. The signal voltage induced in the aerial of a radio receiver is of the order of ___________

  20. A.

     mV

    B.

     µV

    C.

     V

    D.

     None of the above