A specialized oscilloscope used to display the color information in a video signal. In particular, a vectorscope decodes the color information into R - Y & B - Y. Those signals are used to drive the x and y axis of the scope. Total lack of color in a video signal is displayed as a dot in the center of the vectorscope display. The angle, distance around the circle, and magnitude, distance away from the center, indicate the phase and amplitude of the color signal.