Covariance rotation with perspective projection for creating radar search volumes from remote cues

Abstract

A radar installation searches a limited volume within view, such as a covariance ellipsoid where a target is expected to be found based on a cue from a remote radar. The radar activates beams selected from an angularly diverging array of beams spanning the azimuth and elevation of an acquisition face whose area increases with range from the radar. A controller projects the search volume relative to the acquisition face, for selecting beam positions intersecting the search volume, and activates beams for a time interval that determines maximum range. A coordinate transformation is effected, so that with decreasing range, the angular divergence between projected points of the search volume is correspondingly increased, including points tangent to outer edges of the ellipsoid. The search volume accurately corresponds to the covariance ellipsoid by accounting for perspective in this way, reducing the time needed to examine the search volume for the target.