Digital display generators

Claim 2

A digital display generator for producing simulated coastline display for a radial-scan radar comprising first storage means operable to store signals representing the cartesian co-ordinates of each of a plurality of spaced points along a required simultaed coastline relative to a fixed datum, second storage means operable to store signals representing a number of sets of elements each set being defined by one of said spaced points and determining the simulated coastline between said one point and the next, computer means operable to determine, for each stroke of the radial scan, the set or sets of elements in which at least one element may intersect the scan stroke and to transform the co-ordinates of the spaced point defining the or each such set of elements relative to a variable datum, and logic means operably interconnected to said computer means and said second storage means for determining, for each scan stroke, the presence of such an intersection and the range from the variable datum of the point of intersection of the stroke and the nearest one of said intersecting elements.

Claim 3

A digital display generator as claimed in claim 1 in which the logic means includes means for representing each element as a straight line of unit length in one of a fixed number of directions from a point.

Claim 4

A digital display generator as claimed in claim 1 in which the logic means includes means for representing each element as a straight line of unit length in one or the other sense in either of two perpendicular co-ordinate directions from a point to give four directions from said point.

Claim 5

A digital display generator as claimed in claim 3 in which the logic means includes means for representing each element as a straight line in either of two perpendicular co-ordinate directions from a point thereby giving four mutually perpendicular directions from said point, said four mutually perpendicular directions represent the four cardinal compass directions.

Claim 6

A digital display generator as claimed in claim 1 in which the logic means includes means operable to determine, for each scan stroke, which element or elements in the or each of said sets of elements intersects the scan stroke.

Claim 7

A digital display generator as claimed in claim 5 in which the logic means includes means for determining for each element in each of said sets of elements, the cartesian co-ordinates of the end of each element and of the point of intersection between the scan stroke and the element or a projection thereof in a fixed predetermined co-ordinate direction, and the sense of the direction from the end of the element to said point of intersection, a change in the sense of this direction relative to that for the previous element denoting an intersection between the element and the scan stroke.

Claim 8

A digital display generator as claimed in claim 6 in which the logic means includes means for determining the range from the variable datum of each one of said points of intersection between an element and the scan stroke and means for passing to the computer the parameters of the element containing the point of intersection nearest to said datum.

Claim 9

A digital display generator for producing a simulated topographical displsy for a radial-scan radar comprising first storage means operable to store signals representing the cartesian co-ordinates of each of a plurality of spaced points along a required simulated topogrphicial contour relative to a fixed datum, second storage means operable to store signals representing a number of sets of elemens each set being defined by one of said spaced points and determining the simulated topographical contour line between said one point and the next, computer means, operable means for interconnecting said computer means and said first storage means, said computer means being operable to determine, for each stroke of the radial scan, thE set or sets of elements in which at least one element may intersect the scan stroke and to transform the co-ordinates of the spaced point defining the or each such set of elements relative to a variable datum, the logic means interconnected to said computer means and said second storage means for determining, for each scan stroke, the presence of such an intersection and the range from the variable datum of the point of intersection of the stroke, and the nearest one of said intersecting elements.

Claim 10

A digital display generator for producing a simulated topographical displsy for a radial-scan radar comprising first storage means operable to store signals representing the cartesian co-ordinates of each of a plurality of spaced points along a required simulated topogrphicial contour relative to a fixed datum, second storage means operable to store signals representing a number of sets of elemens each set being defined by one of said spaced points and determining the simulated topographical contour line between said one point and the next, computer means, operable means for interconnecting said computer means and said first storage means, said computer means being operable to determine, for each stroke of the radial scan, thE set or sets of elements in which at least one element may intersect the scan stroke and to transform the co-ordinates of the spaced point defining the or each such set of elements relative to a variable datum, the logic means interconnected to said computer means and said second storage means for determining, for each scan stroke, the presence of such an intersection and the range from the variable datum of the point of intersection of the stroke, and the nearest one of said intersecting elements.

Claim 11

A digital display generator as claimed in claim 8 in which the logic means includes means for representing each element as a straight line of unit length drawn in one of a fixed number of directions from a point.

Claim 12

A digital display generator as claimed in claim 9 in which the logic means includes means for representing each element as a straight line of unit length in one or the other sense in either of two perpendicular co-ordinate directions to give four mutually perpendicular directions from said point, said four mutually perpendicular directions representing the four cardinal compass directions.

Claim 13

A digital display generator as claimed in claim 8 in which the logic means includes means operable to determine, for each scan stroke, which element or elements in the or each of said sets of elements intersects the scan stroke.

Claim 14

A digital display generator as claimed in claim 11 in which the logic means includes means for determining for each element in each of said sets of elements, the cartesian co-ordinates of the end of each element and of the point of intersection between the scan stroke and the element or a projection thereof in a fixed predetermined co-ordinate direction, and the sense of the direction from the end of the element to said point of intersection, a change in the sense of this direction relative to that for the previous element denoting an intersection between the element and the scan stroke.

Claim 15

A digital display generator as claimed in claim 12 in which the logic means includes means for determining the range from the variable datum of each one of said points of intersection between an element and the scan stroke and means for translating to the computer signals representing the parameters of the element containing the point of intersection nearest to said datum.