Sunday 15 December 2013

TELEVISION ENGINEERING (T.V.FUNDAMENTALS)-Tamilnadu Polytechnic one mark question and Answers (L-Sheme )


What is Television or TV?
Ans : Television means “to see from distance” is a system for converting visual images (with sound) into electrical signals, transmitting them by radio or other means, and displaying them electronically on a screen.
What is the use of Camera Tube?
Ans : Camera tube is used to convert an optical image into electrical signals.
What is the use of Picture Tube?
Ans : Picture Tube is used in television receivers to produce an image by varying the electron-beam intensity as the beam is deflected from side to side and up and down to scan a raster on the fluorescent screen at the large end of the tube
What is the use of Microphone?
Ans : Microphone is used to convert Sound waves to corresponding electrical variations for the Audio Signal.
What is the use of Loud Speaker?
Ans :Loud Speaker is used in television receivers to convert electrical Variations to the Original Sound Waves for the audio signal.
Which type of modulation is used for transmitting audio signal?
 Ans : Frequency Modulation is used for transmitting audio signal in televisions.
 Mention the Frequency of Horizontal Scanning and Vertical Scanning used in TV system?
  • Horizontal Scanning Frequency is 15,625 Hz.
  • Vertical Scanning Frequency is 25 Hz.
How Many Frames are scanned in one second?
Ans : There are 25 frames are scanned in one Second.
Mention the Various Pulses Placed in the Vertical blanking duration intervals. 
  • Horizontal Sync Pulses
  • Five Pre equalising Pulses
  • Serrated Vertical Pulse
  • Five Post equalizing Pulses.
Mention the time periods of front porch and back porch. 
  • Front Porch – 1.5µs
  • Back Porch – 5.8µs
What is the use of Back Porch? 
Ans : At the Receiver,it is used to AGC Voltage proportional to the signal strength picked up at the antenna.
What is the use of equalizing pulses? 
Ans : Equalizing pulses are used to shift the half line discrepancy away both from the beginning and end of vertical sync pulses.
 Define Negative Modulation?
Ans :The Intensity of picture brightness causes decreases in amplitude of the modulated envelope, it is called negative modulation.
 Mention any two merits of negative modulation. 
  • Noise interference on picture signal is low.
  • Noise interference on synchronization is low.


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