3. Reverse compatibility (fig 1-11) or black and white reception on a color
receiver is the next requirement.
A black and white signal' transmitted by a
monochrome system is split three ways and is applied to the red, blue and green
electron gun cathodes of a tricolor kinescope. Before the signal is applied to its
electron guns, the tricolor tube is adjusted to produce a white raster.
white raster is obtained, the signal is applied to all three guns and the black and
white signal being transmitted produces a monochrome picture on the tricolor
kinescope. In the process of producing a white screen, the kinescope automatically
separates the brightness signal into a ratio of 30 percent red, 11 percent blue,
and 59 percent green as the signal is applied to the electron guns.