Color TV Signal

A color TV signal starts off looking just like a black-and-white signal. An extra chrominance signal is added by superimposing a 3.579545 MHz sine wave onto the standard black-and-white signal. Right after the horizontal sync pulse, eight cycles of a 3.579545 MHz sine wave are added as a color burst.


Following these eight cycles, a phase shift in the chrominance signal indicates the color to display. The amplitude of the signal determines the saturation. The following table shows you the relationship between color and phase:

Color
Phase
Burst
0 degrees
Yellow
15 degrees
Red
75 degrees
Magenta
135 degrees
Blue
195 degrees
Cyan
255 degrees
Green
315 degrees

A black-and-white TV filters out and ignores the chrominance signal. A color TV picks it out of the signal and decodes it, along with the normal intensity signal, to determine how to modulate the three color beams.