Quadruplexing: An NTSC-compatible encoding technique that assures crosstalk-free transmission of luminance, chrominance, and two new signals

Quadruplexing is a new NTSC-compatible video encoding technique that allows full separation of luminance and chrominance information under all conditions, as well as the transmission and separation of 3.0 MHz of additional information which may be used by advanced television systems, such as ACTV. Quadruplexing relies on the inability of the eye (and most TV cameras) to perceive detail in motion. The method doesn't send more information in the given 4.2 MHz bandwidth-strictly speaking, that's impossible. Instead, it sends less luminance information (that part of luminance which the eye doesn't see anyway) and sends other information in its place.<>