Cartographic indicator system

Claim 1

A cartographic indicator system aboard an aircraft, comprising: data-storing means including a video disk, carrying prerecorded information reproducible on a screen of a cathode-ray tube as an image of a map of territory overflown by the aircraft, and reading means for extracting the information carried on selected portions of said disk, the information in said portions relating to image points of respective rectangular zones of a map to be visualized, said zones all having the same width and height, said map being subdivided into a plurality of bands extending in a first reference direction Y and adjoining one another in a second reference direction X orthogonal to said direction Y, each of said bands having a width equal to that of said zones in said direction X and containing a multiplicity of said zones adjoining one another in said direction Y, one of said reference directions corresponding to geographic longitude, the other of said reference directions corresponding to geographic latitude; sensing means for supplying coordinate signals S X , S Y representing geographical position and a rotational signal S.sub.θ representing heading of the aircraft at any instant; an intermediate memory with cells arranged in a multiplicity of rows of a matrix, said multiplicity exceeding the number of cells necessary for storing the data relating to all the image points of a zone, the number of rows and the number of cells per row being at least equal to the number of image points lying in the diagonal of a zone to facilitate a visual representation of the map image in any angular orientation upon sequential readout of said cells; monitoring means including a cathode-ray tube connected to said intermediate memory; and processing means responsive to said sensing means for controlling the loading of said cells with data extracted from selected portions of said disk in a manner enabling a display of a map image on the screen of said cathode-ray tube, upon sequential readout of said cells, with variable angular orientation determined by said rotational signal S.sub.θ.