This set of Video Engineering Multiple Choice Questions & Answers focuses on “Television Fundamentals – Composite Video Signal”.
1. What is the full form of CVS?
a) Composite video signal
b) Composite video system
c) Color video system
d) Composite value signal
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Explanation: CVS stands for composite video signal. As the name suggests, composite video signal is composed of more than one information signals. It is also often designated as CVBS, where C stands for color, V for video, B for burst and S for sync.
2. What is the period of one scanning line in composite video signal?
a) 52 μs
b) 25 μs
c) 36 μs
d) 64 μs
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Explanation: The composite video signal consists of the luminance or brightness information of the picture, Chroma signal or color information, color burst, horizontal blanking pulse and sync pulse. The CVS correspond to one scanning line of a video signal which is equal to 64 μs.
3. How much cycles do the color burst (CB) in the composite video signal consists of?
a) 1 to 3
b) 4 to 6
c) 3 to 5
d) 8 to 10
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Explanation: Color burst (CB) which consists of 8 to 10 cycles of color subcarrier signal, is used to keep the chrominance subcarrier synchronized in a color television signal. By synchronizing an oscillator with the color burst at the back porch of the horizontal sync pulse, a television receiver is able to restore the suppressed carrier off the chrominance signal, and in turn decode the color information.
4. What is the range of peak white level in composite video signal?
a) 72 %
b) 50 to 70 %
c) 10 to 12.5 %
d) 75 %
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Explanation: The video signal varies between certain limits. The range of peak white level in composite video signal is 10 to 12.5 %. The black level comes at the height of 72 %. From 75 % to 100 % there is a blanking level.
5. What is termed as the difference between black level and blanking level?
a) Pedestal
b) Pedestal height
c) Black level
d) DC level
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Explanation: Pedestal is termed as difference between black level and blanking level. While pedestal height is defined as distance between the pedestal level and the DC level which indicates the average brightness.
6. Average brightness does not change from frame to frame and from line to line.
a) True
b) False
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Explanation: The above statement is false. Average brightness can change only from frame to frame and not from line to line. If the pedestal height is low, the scene is darker and if the pedestal height is larger, it means the scene have higher average brightness.
7. The horizontal sweep is of 64 μs in composite video signal.
a) True
b) False
View Answer
Explanation: In the CVS(Composite Video Signal) the horizontal sweep is of 64 μs which include picture details (52 μs) along with that horizontal blanking pulse (12 μs) which shuts off the electron gun during horizontal retrace. The horizontal sync pulses are required to synchronize the horizontal oscillator of the TV receiver to reproduce sawtooth voltage on the horizontal deflection plate so that scanning of the line can start.
8. What will be the voltage if the picture is darker in composite video signal?
a) Lower
b) Higher
c) Constant
d) Varying
View Answer
Explanation: Darker the picture, higher will be the voltage within those limits. Video signal has average brightness value or DC component corresponding to the average brightness of the scene. Average brightness can change only from frame to frame and not from line to line.
Sanfoundry Global Education & Learning Series – Video Engineering.
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