Colour Encoder in Colour TV – Block Diagram | New Topic

In this note, we are going to know about Colour Encoder in Colour TV and Its Block Diagram. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.

Author Name: Arun Paul.

What is Colour Encoder in Colour TV?

A color encoder is an electronic circuit or mechanism found in color televisions that converts RGB (Red, Green, and Blue) signals into composite video signals. It modulates color information into a carrier wave by mixing luminance (Y), chrominance (U & V), and synchronization signals to ensure that color images are sent and shown correctly.

Importance of Colour Encoder in Television

• Colour signal conversion.
• Efficient transmission.
• Maintains colour accuracy.
• Synchronization with Display Devices
• Compatibility with Older Systems

Block Diagram of Colour Encoder in Colour TV

Here is the colour encoder block diagram in colour television –

• Composite Video Signal: The composite video signal includes both luminance (brightness) and chrominance (color) information in a single channel. It is transmitted as an analog signal and includes sync pulses to ensure image stability. This signal is required for appropriate color reproduction, ensuring that all details, contrast, and shades are conveyed correctly to the TV.
• 1st Stage Video Amplifier: This stage strengthens the composite video signal prior to further processing. It ensures low distortion while maintaining signal integrity. Amplification compensates for signal loss caused by transmission across long distances. Without this amplification, the image quality may deteriorate, resulting in a poor or unclear visual output on the display.
• Relay Line: A relay line transfers the amplified signal to the next processing stage. It functions as a buffer, ensuring that there is no major loss in signal quality. Relay lines are intended to guarantee transmission stability while also preventing unwanted interference that could cause output distortions.
• 2nd Stage Video Amplifier: This amplifier amplifies the video signal obtained from the first amplifier. It enhances the signal before it enters the display processing circuitry. The second stage of amplification is critical for improving image quality, ensuring color consistency, and preparing the signal for conversion into primary color components for display.
• PAL-D Decoder: The PAL-D decoder separates the chrominance (color) components of the composite video output. It distinguishes between U (blue difference) and V (red difference) signals, allowing for more accurate color composition. PAL-D is a popular color encoding technique in television transmission that ensures accurate synchronization and color stability.
• Matrix Circuit: To generate RGB (Red, Green, and Blue) signals, the matrix circuit combines U and V signals as well as the brightness (Y). These primary colors are employed to create the final image on the television screen. The matrix guarantees that colors are appropriately represented and shown in the appropriate proportions.
• Output to Picture Tube: The final RGB signals are fed into the picture tube, which controls electron beams in a CRT TV or pixel illumination in a contemporary display. The appropriate combination of these signals produces full-color image reproduction. This assures colorful and sharp visuals, providing a high-quality viewing experience for the audience.