The composite video synchronous signal carries the luminance (typically referred to as black and white television) information of a television picture. To include color in the video signal, additional chrominance information needs to be overlaid. In Europe, the Phase Alternating Line (PAL) standard was introduced in 1967. It defines an IQ-modulated color subcarrier that is placed at a frequency of 4.43 MHz. Two color-difference signals referred to as U and V can be found on this subcarrier. PAL involves the alternation of the phase with each video line. Therefore, phase errors have no influence on the displayed color information. The combination of the luminance as well as the chrominance information results in the composite color video signal (CCVS).
