RS-170 RGB refers to RGB signals timed to RS-170 specifications. In RS-170 RGB, the red, green and blue signals are actually three individual monochrome signals representing their respective red, green, and blue colors which conform to the RS-170 video format, and which share one composite sync signal which is (usually) combined with the green signal. Although video intensity information and blank timing intervals are present in the red and blue signals, the composite synchronization pulses typically are not. Alternatively, a fourth signal containing only the composite synchronization information may be used to drive an external synchronization input of an RGB display. Some computer graphic displays and some cameras require separate horizontal and vertical drive inputs as well and may require Transistor/Transistor Logic (TTL) voltage pulses (3-5 V).