Algorithm for radar coordinate conversion in digital scan converters
First Claim
1. A system for high speed coversion of polar coordinates of radar returns from radially spaced apart radar pulses into cartesian coordinates for storage in a digital memory comprising means for determining an initial Xi,Yi address corresponding to where a radar pulse crosses a raster display at an angle θ
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i, means for determining subsequent addresses Xi+1 and Yi+1 for said pulse by adding constant values sin θ
i and cosθ
i to Xi and Yi, means for storing data representative of said radar returns at said addresses Xi and Yi, and means for filling said display between adjacent radar pulses at ranges where spoking tends to occur with data related to the data stored at each address Xi, Yi.
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Abstract
Disclosed is a system for high speed conversion of radar formats from polar coordinates to cartesian coordinates. From an initial address Xi Yi where a radar pulse crosses a display, subsequent addresses are determined by adding constant values sin θi and cos θi to Xi and Yi. This is faster than the prior method of calculating xi and Yi by multiplying Ri (range) by sin θi and cos θi. Also disclosed is a system for filling the display between adjacent radials at long ranges where spoking of the display tends to occur. This is done by adding constant increments to one cartesian value on one vector until the next vector is reached while maintaining the other cartesian value constant.
30 Citations
6 Claims
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1. A system for high speed coversion of polar coordinates of radar returns from radially spaced apart radar pulses into cartesian coordinates for storage in a digital memory comprising means for determining an initial Xi,Yi address corresponding to where a radar pulse crosses a raster display at an angle θ
-
i, means for determining subsequent addresses Xi+1 and Yi+1 for said pulse by adding constant values sin θ
i and cosθ
i to Xi and Yi, means for storing data representative of said radar returns at said addresses Xi and Yi, and means for filling said display between adjacent radar pulses at ranges where spoking tends to occur with data related to the data stored at each address Xi, Yi. - View Dependent Claims (2, 3, 4)
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i, means for determining subsequent addresses Xi+1 and Yi+1 for said pulse by adding constant values sin θ
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5. A system for high speed conversion of polar coordinates of radar returns from radially spaced apart radar pulses into cartesian coordinates for storage in a digital memory comprising means for determining an initial Xi, Yi address corresponding to where a radar pulse crosses a raster display at an angle θ
-
i, means for determining subsequent addresses Xi+1 and Yi+1 for said pulse by adding constant values sin θ
i and cosθ
i to Xi and Yi, means for storing data representative of said radar returns at said addresses Xi and Yi, and means for filling said display between adjacent radar pulses at ranges where spoking tends to occur with data related to the data stored at each address Xi, Yi, said means for filling comprising means for sequentially addressing a plurality of locations spaced apart along one cartesian axis from a location representing one radar pulse to a location representing a subsequent radar pulse while maintaining a constant value for the address along the other cartesian axis, said locations being spaced apart a constant distance for any two adjacent radar pulses, and wherein said distance is cosθ
tanθ
'"'"' for filling along the x-axis and r sinθ
cotθ
'"'"' for filling along the y-axis, wherein θ
is the angle between said first radar pulse and the y-axis and θ
'"'"' is the angle between said subsequent radar pulse and the y-axis. - View Dependent Claims (6)
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i, means for determining subsequent addresses Xi+1 and Yi+1 for said pulse by adding constant values sin θ
Specification