Patent US 4,081,802

A display system for simultaneously showing slewed radar and navigation ct information on a real time basis. A slewed radar signal from a ship mounted radar is processed to maintain the terrain as a fixed display and the moving ship, upon which the radar is mounted, as a moving display. A video TV signal is also generated that represents a navigation chart that corresponds to the slewed radar signal. The TV signal representing the processed slewed radar signal is mixed with the navigation chart TV signal and both are simultaneously presented on a TV display. The navigation chart TV signal is adjusted so that the terrain is matched to and is coincident with the terrain of the processed slewed radar signal. The TV display, therefore, presents both slewed radar information and navigation chart information wherein the navigation chart information is fixed on the TV display and all radar presented information that moves with respect to the terrain moves on the TV display.