logo

CuriousTab

CuriousTab

Discussion

Home ‣ Electronics and Communication Engineering ‣ Communication Systems Comments
  • Question

  • In colour TV receiver, varactor diode is used for


  • Options
  • A. detection
  • B. rectification
  • C. tuning
  • D. both (a) and (b)

  • Correct Answer
  • tuning 

    Explanation
    In varactor diode the applied reverse bias controls the width and therefore capacitance of depletion layer.

    This capacitance is used for tuning.

    Communication Systems problems

    Search Results

    • 1. Which of the following cannot be the Fourier series expansion of a periodic signal?

    • Options
    • A. x(t) = 2 cos t + 3 cos 3t
    • B. x(t) = 2 cos pt + 7 cos t
    • C. x(t) = cos t + 0.5
    • D. x(t) = 2 cos 1.5pt + sin 3.5 pt
      • Discuss
    • 2. If C is capacity of noisy channel, (bits/s), ?f is bandwidth Hz and S/N is signal to noise ratio, then

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 3. A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. Which of the following frequency is least likely to be present in the output?

    • Options
    • A. 1002 kHz
    • B. 1000 kHz
    • C. 999.2 kHz
    • D. 998.0 kHz
      • Discuss
    • 4. Tracking of extra terrestrial objects requires

    • Options
    • A. high transmitting power
    • B. very sensitive receiver
    • C. fully steerable antenna
    • D. all of the above
      • Discuss
    • 5. In sound recording the degree of pre-emphasis is about 6 dB/ octave.

    • Options
    • A. True
    • B. False
      • Discuss
    • 6. Frequency shift keying is used mostly in

    • Options
    • A. telegraphy
    • B. telephony
    • C. satellite communication
    • D. radio transmission
      • Discuss
    • 7. Which of the following has the highest input impedance?

    • Options
    • A. CE
    • B. CB
    • C. CC
    • D. Push pull
      • Discuss
    • 8. Degaussing in a picture tube means

    • Options
    • A. Adding magnetism in mask and mounting frame
    • B. Removing residual magnetism in mask, shield etc...
    • C. Increasing resistance of coils to decrease time constant
    • D. Decreasing resistance of coils to increase time constant.
      • Discuss
    • 9. Space wave may be a direct wave or wave reflected from earth.

    • Options
    • A. True
    • B. False
      • Discuss
    • 10. If the bandwidth is increased by 2, the ?FM ?AM (where ? is the ratio of SNR of output to SNR at input, FM is frequency modulation and AM is amplitude modulation) is increased by a factor of

    • Options
    • A. 2
    • B. 3
    • C. 4
    • D. 6
      • Discuss

    Comments

    There are no comments.
Enter a new Comment




Aptitude

Engineering

Programming

Reasoning

Links

Copyright ©CuriousTab. All rights reserved.