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ECE :: Radio Receivers

  1. The selectivity curve of a standard receiver is represented by

  2. A.
    curve A
    B.
    curve B
    C.
    curve C
    D.
    curve D

  3. Which of the following statement about the advantage of phase discriminator over the slope detector is false?

  4. A.
    Fewer tuned circuits
    B.
    Better linearity
    C.
    Greater limiting
    D.
    Much easier alignment

  5. Fidelity of a receiver represents

  6. A.
    the sensitivity expressed in terms of voltage that must be applied to the receiver input to give a standard output
    B.
    the extent to which the receiver is capable of distinguishing between the desired signal and other frequencies
    C.
    the variation of the output with the modulation frequency when the output impedance is a resistance
    D.
    none of the above

  7. Which of the following produces upper and lower side frequencies?

  8. A.
    Microphone
    B.
    Demodulator in a superheterodyne receiver
    C.
    Modulator in a. radio transmitter
    D.
    Oscillator in a receiver

  9. The passband of the tuned circuits of a radio receiver should be equal to

  10. A.
    20 kHz
    B.
    455 kHz
    C.
    1455 kHz
    D.
    more than 455 kHz

  11. In a broadcast superheterodynes receiver having no RF amplifier, the loaded Q of the antenna coupling circuit is 100. If the intermediate frequency is 455 kHz. In receivers operating upto the limit of shortwave broadcasting the local oscillator often used is

  12. A.
    Armstrong oscillator
    B.
    Colpitts oscillator
    C.
    Clapp oscillator
    D.
    Ultra Audio oscillator

  13. RF amplifiers are used in radio receivers for

  14. A.
    better sensitivity
    B.
    improved signal-to-noise ratio
    C.
    better coupling of receiver to the antenna
    D.
    all of the above

  15. In an FM signal, the power

  16. A.
    increases as the modulation index increases
    B.
    reduces as the modulation index increase
    C.
    increases as the modulation index decreases
    D.
    remains constant when the modulation index increases

  17. An unmodulated voltage 10 V effective is applied to a dioxide detector in which load resistance is 4 x 10-5 ohms. A micrometer shows that the rectified DC current in this resistance is 30 A. The efficiency of detection is

  18. A.
    34%
    B.
    55.5%
    C.
    68.8%
    D.
    84.7%

  19. Selectivity varies with receiving frequency, frequency is raised.

  20. A.
    Somewhat better when the receiving frequency is raised
    B.
    Somewhat better at intermediate frequency
    C.
    Somewhat worse when the receiving frequency is lowered
    D.
    Somewhat worse when the receiving frequency is raised