a) This nonlinear distortion is often referred to as “diff phase” or “dP.” It is present if a signal’s chrominance phase is affected by the luminance level. It occurs because of the system’s inability to uniformly process the high-frequency chrominance information at all luminance levels. Diff Phase is expressed in degrees of subcarrier phase. The subcarrier phase can be distorted such that the subcarrier phase is advanced (lead or positive) or delayed (lag or negative) in relation to its original position. In fact, over the period of a video line, the subcarrier phase can be both advanced and delayed. For this reason, it is important to specify whether “peak to peak diff phase” is being specified or “maximum deviation from 0” in one direction or another. Normally the “peak to peak diff phase” is given. dP distortions cause changes in hue when picture brightness changes. Colors may not be properly reproduced, particularly in high-luminance areas of the picture. b) The phase change of the 3.6 MHz color subcarrier introduced by the overall circuit, measured in degrees, as the subcarrier is varied from blanking to white level.