초록 ▼

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 fac

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.

대표청구항 ▼

1. A computer implemented method for locating a radar search target, comprising: providing a radar installation with an array of adjacent beam positions diverging angularly from a radar transceiver coupled to a radar command and control processor, the radar command and control processor being operab

1. A computer implemented method for locating a radar search target, comprising: providing a radar installation with an array of adjacent beam positions diverging angularly from a radar transceiver coupled to a radar command and control processor, the radar command and control processor being operable for selectively activating transmitted beams and monitoring for reflected beams at least for a subset of the beam positions between limits of azimuth and elevation, the array of beam positions defining an acquisition face along one of a plane and a spherical surface, normal to a centerline of the radar installation and having an area increasing with range from the radar installation, wherein a time interval for activation of the beams defines a near and far range for the beams, between minimum and maximum limits of range;identifying using said radar command and control processor at least one search volume to be examined for a presence of at least one search target;projecting using the radar command and control processor the search volume onto the acquisition face and operating the controller for activating beam positions that correspond on the acquisition face to projected portions of the search volume;wherein said projecting of the search volume onto the acquisition face includes correcting using the radar command and control processor for differences of perspective caused by certain portions of the search volume being closer to the radar installation than other portions of the search volume. 2. The method of claim 1, wherein the search volume is defined by coordinate positions of points defining a three dimensional geometric shape in a coordinate system, and wherein said correcting for the differences of perspective for projecting the search volume onto the acquisition face comprises applying a matrix conversion to the coordinate positions of the points. 3. The method of claim 2, wherein the search volume is at least partly defined by a three dimensional numeric function in the coordinate system, and projecting the search volume onto the acquisition face comprises applying the matrix conversion to the numeric function defining the search volume. 4. The method of claim 1, wherein the search volume is defined by a covariance ellipsoid defining a volume in which the at least one search target is expected to be located, based on a cue comprising at least one of a previous location, a previous velocity vector, and an expected target category. 5. The method of claim 1, wherein the search volume is defined by a covariance ellipsoid defining a volume in which the at least one search target is expected to be located, based on a cue reported from a remote radar installation. 6. The method of claim 1, wherein said correcting for differences of perspective comprises calculating a differential angle between points of the search volume, and relatively increasing and decreasing the differential angle between points as a function of a range that is nearer and farther from the radar installation, respectively. 7. The method of claim 6, wherein said correcting for differences of perspective comprises determining a differential angle between points of the search volume, at least one of said points being an outer edge of the search volume, and modifying the differential angle as a function of range. 8. The method of claim 7, wherein the at least one of said points on the outer edge is located as a tangent point on a covariance ellipse. 9. The method of claim 6, further comprising determining in azimuth and elevation an angular extent of the search volume as corrected for said differences in perspective, associating a set of beam positions that correspond to the search volume as corrected, and operating the radar installation to apply said transmitted beams, wherein the subset of beam positions corresponds to projection of the search volume on to the acquisition face as corrected. 10. The method of claim 9, further comprising determining at least a far range extent of the search volume as corrected for said differences in perspective, and wherein the controller is operable to maintain said monitoring for reflected beams as necessary to detect reflected beams from the at least one search target up to the far range extent. 11. The method of claim 6, wherein said correcting for differences of perspective comprises the steps of: projecting a 3D covariance ellipsoid onto a range-traverse plane and onto a range-elevation plane to thereby produce two-D ellipses, one being on each of said range-traverse and range-elevation planes;determining maximum angular extents in said two ellipses in each of the range-transverse and range-elevation planes;determining ranges at which margins of said two ellipses occur and from said ranges and said two-D ellipses, determining subtended angles between the margins;increasing the subtended angles between the margins with decreasing range and decreasing the subtended angles with increasing range, thereby accounting for differences of perspective;deeming the increased and decreased subtended angles to be the angle representing the total extents in said transverse and elevation directions; and,controlling the radar to search within limits of angular extent corresponding to the increased and decreased subtended angles. 12. The method of claim 11, further comprising controlling the radar to search with limits of maximum and minimum range of the 2-D ellipses. 13. A computer implemented method for locating a radar search target, comprising: providing a radar installation with an array of adjacent beam positions diverging angularly from a radar transceiver coupled to a controller, the controller being operable for selectively activating transmitted beams and monitoring for reflected beams at least for a subset of the beam positions between limits of azimuth and elevation, the array of beam positions defining an acquisition face along one of a plane and a spherical surface, normal to a centerline of the radar installation and having an area increasing with range from the radar installation, wherein a time interval for activation of the beams defines a near and far range for the beams, between minimum and maximum limits of range;identifying in a processor at least one search volume to be examined for a presence of at least one search target;projecting in the processor the search volume onto the acquisition face and operating the controller for activating beam positions that correspond on the acquisition face to projected portions of the search volume;correcting in the processor for differences of perspective caused by certain portions of the search volume being closer to the radar installation than other portions of the search volume, wherein correcting for difference of perspective comprises: projecting a 3D covariance ellipsoid onto a range-traverse plane and onto a range-elevation plane to thereby produce two-D ellipses, one being on each of said range-traverse and range-elevation planes;determining maximum angular extents in said two ellipses in each of the range-transverse and range-elevation planes;determining ranges at which margins of said two ellipses occur and from said ranges and said two-D ellipses, determining subtended angles between the margins;increasing the subtended angles between the margins with decreasing range and decreasing the subtended angles with increasing range, thereby accounting for differences of perspective;deeming the increased and decreased subtended angles to be the angle representing the total extents in said transverse and elevation directions; and,controlling the radar to search within limits of angular extent corresponding to the increased and decreased subtended angles. 14. A non-transitory computer readable medium configured to store instructions which when executed by a processor cause the processor to perform the steps of: selectively activating transmitted beams and monitoring for reflected beams for at least a subset of beam positions between limits of azimuth and elevation provided by a radar installation having an array of adjacent beam positions diverging angularly from a radar transceiver, the array of beam positions defining an acquisition face along one of a plane and a spherical surface, normal to a centerline of the radar installation and having an area increasing with range from the radar installation, wherein a time interval for activation of the beams defines a near and far range for the beams, between minimum and maximum limits of range;identifying at least one search volume to be examined for a presence of at least one search target;projecting the search volume onto the acquisition face including correcting for differences of perspective caused by certain portions of the search volume being closer to the radar installation than other portions of the search volume;and activating beam positions that correspond on the acquisition face to projected portions of the search volume. 15. The non-transitory computer readable medium of claim 14, further comprising instructions that when executed by a processor cause the processor to perform the steps of: calculating a differential angle between points of the search volume, and relatively increasing and decreasing the differential angle between points as a function of a range that is nearer and farther from the radar installation, respectively. 16. The non-transitory computer readable medium of claim 14, further comprising instructions that when executed by a cause the processor to perform the steps of: projecting a 3D covariance ellipsoid onto a range-traverse plane and onto a range-elevation plane to thereby produce two-D ellipses, one being on each of said range-traverse and range-elevation planes;determining maximum angular extents in said two ellipses in each of the range-transverse and range-elevation planes;determining ranges at which margins of said two ellipses occur and from said ranges and said two-D ellipses, determining subtended angles between the margins;increasing the subtended angles between the margins with decreasing range and decreasing the subtended angles with increasing range, thereby accounting for differences of perspective;deeming the increased and decreased subtended angles to be the angle representing the total extents in said transverse and elevation directions; and,controlling the radar to search within limits of angular extent corresponding to the increased and decreased subtended angles.