Consumer Electronics

CHROMINANCE SIGNAL

The generation of chrominance signal involves the separation of the luminance signal, E_Y from the natural colour signals, E_R, E_G and E_B. This is shown in Fig. 31.6. The natural colour signals E_R, E_G and E_B are developed across resistors R₁, R₂ and R₃ respectively. Part of the voltage across these resistors (0.3 V across R₁, 0.59 V across R₂, and 0.11 V across R₃) is tapped off. The full potential difference across R₁, R₂ and R₃ is simultaneously fed to the adders in stages 2, 3 and 4.

When a white scene is being televised, the three pick-up tubes will extract the three primary colours from the white light and develop corresponding voltages across R₁ R₂ and R₃. Since light falls on all the three pick-up tubes with the same intensity, ...