In this note, we are going to explain Composite Video Signal for Monochrome TV. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.
Author Name: Arun Paul.
Composite Video Signal for Monochrome TV
A composite video signal for a monochrome (black-and-white) television is an analog video transmission that includes both luminance (brightness) and synchronization signals in a single channel. It has no color (chrominance) information because monochrome televisions only display shades of gray.
Components of Composite Video Signal for Monochrome TV
- Luminance (Y): Represents the brightness level of the image, determining different shades of gray.
- Horizontal Sync Pulse: Synchronizes the start of each horizontal scan line.
- Vertical Sync Pulse: Synchronizes the start of each new frame.
- Blanking Intervals: Ensures that the retrace (return) of the electron beam is invisible.
Function of Composite Video Signal for Monochrome TV
The composite video signal ensures that video frames are properly sent and shown on a CRT-based monochrome TV by directing the electron beam to scan the screen in a structured manner.
Composite Video Signal Diagram
Here we have discussed the composite video signal waveform with explanation –
As all components of a composite video signal are to be received on one single channel (7MHz wide), so that they may be tuned by a single tuner, all these must be located properly within the channel.
The blanking pulse, sync pulses, color-burst signal, and actual video signal ( picture brightness and color information) all form one composite signal called composite video signal (or CVS) as shown in Fig, for one H- scanning line. Percentages indicated in the figure, represent amplitude in terms of percentage of carrier level. The width of the pulses has also been shown.
The vertical blanking pulse is of much longer duration (1280 us than the H-blanking pulse, and appears 50 times per second. Five pre-equalizing pulses are superimposed on the blanking pulse before and an equal number of post-equalizing pulses after the V-sync pulse to ensure correct interlacing. The V-sync pulse(2.5 H-width in India) is serrated after every H/2(32 us) interval to ensure the continuation of the H-synchronization during the long time interval (160 us) of the V-sync pulse.
Vertical blanking also forms part of the composite video signal in the same way as the horizontal blanking pulse. Vertical blanking pulse is shown in fig, at the end of odd field, and in fig, at the end of even field, Vertical sync is slotted so that H sync is not lost during a long period.
A composite video signal is an analog format that mixes luminance, chrominance, and sync pulses for video transmission. Horizontal and vertical scanning are required to display images on CRTs and some early LCDs, assuring perfect frame and line synchronization.