Figure 3—This is a typical image line for a black-and-white video signal. The image line starts with a 4-µs sync pulse. The video data starts 8 µs after that. CRT televisions need this time to move the image-producing electron beam back to the left of the screen. A color video signal has a 3.58- or 4.43-MHz carrier wave superimposed on this holding the color information.