Definitions for "Differential Phase"
Change of the chrominance phase as function of luminance level. Synonyms: DP
Differential phase is how much the hue changes when the luma level changes (it isn't supposed to). For a video system, the better the differential phase -- that is, the smaller the number specified -- the better the system is at figuring out the correct color.
Variation in the phase of the chrominance subcarrier as the luminance signal on which it rides is varied from blanking to white level.