Method and apparatus to scan convert radar video to television outputs

Claim 1

Apparatus for converting polar format radar video data comprising radar video pixels each having an associated intensity value in a polar raster display into a horizontal raster format output to a TV monitor, wherein the TV monitor includes a display screen including a plurality of pixels and a plurality of scan lines and wherein each pixel has a corresponding X,Y address, wherein the apparatus comprises: (a) means for storing the radar video pixels indexed by radial and angular coordinates; (b) means for translating a display X,Y address into corresponding angular and radial coordinates wherein the translating means further comprises: (i) means for addition by operating on (X/Y) and (1/Y) wherein for each successive scan line the constant (1/Y) is added to the previous (X/Y) to calculate a new (X/Y) and further wherein at the start of each scan line the translating means is loaded with a new (1/Y) and ((X-1)/Y), (ii) means for providing the square root of [(X/Y) 2 +1] so as to yield R R , (iii) means for providing and scaling the arc tangent of (X,Y) so as to yield Θ R , (iv) means for multiplying R R by a scaling factor Y N to obtain -R R , (v) means for adding offsets to -Θ R and -R R wherein the offsets are the coordinates of the first pixel in the polar raster so as to provide Θ FFM and R FFM values, and (vi) means for formatting the Θ FFM and R FFM values as fixed point two's complement 13-bit representations wherein the 10 MSBs of each are provided as an address input to the storage means and the lower 3 bits are stored to maintain proper pipeline phasing; (c) means for scanning the storage means using the translated X,Y address to access at least four radar video pixels surrounding the translated X,Y address; and (d) means for interpolation of a radar intensity value for the translated X,Y address as a function of the intensity values associated with the surrounding pixels.

Claim 7

A method for converting polar format radar video data comprising radar video pixels each having an associated intensity value in a polar raster display into a horizontal raster format output to a TV monitor, wherein the TV monitor includes a display screen including a plurality of pixels and a plurality of scan lines and wherein each pixel has a corresponding X,Y address, wherein the method comprises the steps of: (a) storing the radar video pixels indexed by radial and angular coordinates; (b) translating a display X,Y address into corresponding angular and radial coordinates including the steps of; (i) adding by operating on (X/Y) and (1/Y) wherein for each successive scan line the constant (1/Y) is added to the previous (X/Y) to calculate a new (X/Y) and further wherein at the start of each scan line the translating means is loaded with a new (1/Y) and ((X-1)/Y), (ii) providing the square root of [(X/Y) 2 +1] so as to yield R R , (iii) providing and scaling the arc tangent of (X,Y), (iv) multiplying R R by a scaling factor Y N to obtain -R R , (v) adding offsets to -Θ R and -R R wherein the offsets are the coordinates of the first pixel in the polar raster so as to provide Θ FFM and R FFM values, and (vi) formatting the Θ FFM and R FFM values as fixed point two's complement 13-bit representations wherein the 10 MSBs of each are provided as an address input to the storage means and the lower 3 bits are stored to maintain proper pipeline phasing; (c) scanning the storage means using the translated X,Y address to access at least four radar video pixels surrounding the translated X,Y address; and (d) interpolating a radar intensity value for the translated X,Y address as a function of the intensity values associated with the surrounding pixels.

Claim 8

A method for converting polar format radar video data comprising radar video pixels each having an associated intensity value in a polar raster display into a horizontal raster format output to a TV monitor, wherein the TV monitor includes a display screen including a plurality of pixels and a plurality of scan lines and wherein each pixel has a corresponding X,Y address, wherein the method comprises the steps of: (a) storing the radar video pixels indexed by radial and angular coordinates; (b) translating a display X,Y address into corresponding angular and radial coordinates including the steps of; (i) adding by operating on (X/Y) and (1/Y) wherein for each successive scan line the constant (1/Y) is added to the previous (X/Y) to calculate a new (X/Y) and further wherein at the start of each scan line the translating means is loaded with a new (1/Y) and ((X-1)/Y), (ii) providing the square root of [(X/Y) 2 +1] so as to yield R R , (iii) providing and scaling the arc tangent of (X,Y), (iv) multiplying R R by a scaling factor Y N to obtain -R R , (v) adding offsets to -Θ R and -R R wherein the offsets are the coordinates of the first pixel in the polar raster so as to provide Θ FFM and R FFM values, and (vi) formatting the Θ FFM and R FFM values as fixed point two's complement 13-bit representations wherein the 10 MSBs of each are provided as an address input to the storage means and the lower 3 bits are stored to maintain proper pipeline phasing; (c) scanning the storage means using the translated X,Y address to access at least four radar video pixels surrounding the translated X,Y address; and (d) interpolating a radar intensity value for the translated X,Y address as a function of the intensity values associated with the surrounding pixels.

Claim 12

A method for converting polar format video data comprising video pixels each having an associated intensity value in a polar raster display into a horizontal raster format output to a TV monitor, wherein the TV monitor includes a display screen including a plurality of pixels and wherein each pixel has a corresponding X,Y address, wherein the method comprises the steps of: (a) storing the video pixels indexed by radial and angular coordinates; (b) translating a display X,Y address into corresponding angular and radial coordinates, and wherein the translating step further comprises the steps of: (i) initializing the X,Y coordinates on a line basis; (ii) adding delta x and delta y where delta x=SF.sub.B *COS(Θ), delta y=SF.sub.B *SIN(Θ), Θ is the angle of rotation, and SF B is the display-to-radar coordinate scale factor; (c) scanning the storage means using the translated X,Y address to access at least four video pixels surrounding the translated X,Y address; and (d) interpolating an intensity value for the translated X,Y address as a function of the intensity values associated with the surrounding pixels.

Claim 13

A method for converting polar format video data comprising video pixels each having an associated intensity value in a polar raster display into a horizontal raster format output to a TV monitor, wherein the TV monitor includes a display screen including a plurality of pixels and wherein each pixel has a corresponding X,Y address, wherein the method comprises the steps of: (a) storing the video pixels indexed by radial and angular coordinates; (b) translating a display X,Y address into corresponding angular and radial coordinates, and wherein the translating step further comprises the steps of: (i) initializing the X,Y coordinates on a line basis; (ii) adding delta x and delta y where delta x=SF.sub.B *COS(Θ), delta y=SF.sub.B *SIN(Θ), Θ is the angle of rotation, and SF B is the display-to-radar coordinate scale factor; (c) scanning the storage means using the translated X,Y address to access at least four video pixels surrounding the translated X,Y address; and (d) interpolating an intensity value for the translated X,Y address as a function of the intensity values associated with the surrounding pixels.