A) A picture defect caused by the incorrect relative timing of a signal in relation to another signal. b) A change in the colour subcarrier signal which moves its timing out of phase, i.e., it occurs at a different instant from the original signal. Since colour information is encoded in a video signal as a relation between the colour subcarrier and the colour burst phase, a deviation in the colour subcarrier phase results in a change in the image’s hue.