Home / ECE / Communication Systems :: Section 11

ECE :: Communication Systems

  1. In case of stabilized reactance modulator AFC system

  2. A.
    phase modulator is converted into frequency modulation by equalizer circuit
    B.
    the discriminator must have a fast time constant to provide demodulation
    C.
    the higher discriminator frequency, the better oscillator frequency
    D.
    the discriminator frequency must be too low, or the system will fail

    View Answer

    Workspace

    Discuss Discuss in Forum


  3. Assertion (A): Demodulation of SSB and AM signals is exactly similar

    Reason (R): The basic SSB demodulation device is product detector.

  4. 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


  5. In shot noise

  6. A.
    the current rises around mean value
    B.
    the current rises to peak value, decreases to zero and then again rises
    C.
    the current may become negative
    D.
    the current is always less than the mean value

    View Answer

    Workspace

    Discuss Discuss in Forum


  7. In VCR, the chrominance signal's frequency is

  8. A.
    up converted during recording and down converted during playback
    B.
    down converted during recording and up converted during playback
    C.
    not changed during recording and playback
    D.
    any of the above depending on VCR system

    View Answer

    Workspace

    Discuss Discuss in Forum


  9. Assertion (A): A video monitor does not need RF tuner and IF amplifier

    Reason (R): The picture tube in TV is basically a CRT.

  10. 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


  11. Consider the following statements as regards IF in radio receivers

    1. If IF is too high, poor selectivity and poor adjacent channel rejection could result
    2. If IF is high, tracking difficulties increase
    3. A very low IF makes selectivity too sharp
    4. As IF is decreased, image frequency rejection becomes better
    Which of the above are correct?

  12. A.
    1, 2, 3, 4
    B.
    1, 2, 3
    C.
    2, 3, 4
    D.
    1, 3, 4

    View Answer

    Workspace

    Discuss Discuss in Forum


  13. Audio-signal modulates a 125 MHz carrier, causing a frequency deviation of 5 kHz. The bandwidth of the narrowband FM signal is __________ kHz.

  14. A.
    10
    B.
    8
    C.
    9
    D.
    20

    View Answer

    Workspace

    Discuss Discuss in Forum


  15. Assertion (A): Radar gave birth to microwave technology.

    Reason (R): In radar systems very high frequencies give the most accurate results.

  16. 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


  17. A channel has a SNR of 7 and BW 4 kHz. Keeping the channel capacity (BPS) same, the BW is reduced to accommodate more channels. The SNR

  18. A.
    decreases
    B.
    increases
    C.
    remains same
    D.
    partially affected

    View Answer

    Workspace

    Discuss Discuss in Forum


  19. The output VR of the ratio detector is related with the output VF of similar Foster-Seeley discriminator as follows.

  20. A.
    VR = VF
    B.
    VR < VF
    C.
    VR = 2VF
    D.
    VF = 2VR

    View Answer

    Workspace

    Discuss Discuss in Forum