Differential phase
Differential phase is a kind of linearity distortion which affects the color hue in TV broadcasting. == Composite color video signal == Composite color video signal (CCVS) consists of three terms: Monochrome (luminance) signal Auxiliary signals (sync pulse and blanking signals) Color signal, which is actually a subcarrier modulated by chroma information The first two terms are usually called composite video signal (CVS) The modulation technique of the color subcarrier is quadrature amplitude modulation (QAM) both in PAL and NTSC systems.