Method for scanning a radar search volume within an allowable scan time
AssigneeLockheed Martin Corporation
InventorMark A. Friesel
Life of this patent
Estimating the term…
Abstract
A radar volume in a cued direction is searched with sequential pencil beams. The allowable scan time is limited. The cued direction and uncertainty identify a search face, and the range gives a search volume. The number of beams required to scan the volume is determined, and compared with the maximum time. If less than the maximum, the scan is initiated. If greater than the maximum time, the scan region about the cued volume is subdivided into smaller portions, each of which is scanned sequentially.
Claims18
A method for searching an angular region of a radar search volume about a given cued direction and with a maximum range, where the search of the radar search volume is performed with sequentially applied radar beams having defined beamwidths, said method comprising the steps of:
- acquiring error information;
- from said error information, determining azimuth and elevation extents of a search face of the radar search volume about the cue direction;
- determining an angular extent of each of a plurality of radar beams in azimuth and elevation;
- from said angular extents in azimuth and elevation for each radar beam, determining a number of beams required to cover the search face of the radar search volume;
- determining a dwell time for each of the radar beams given the maximum range;
- taking a product of said number of beams multiplied by the dwell time per beam to obtain a search time;
- comparing said search time with a maximum allowable search time;
- initiating radar scanning over said search face with said number of beams if said search time is less that said maximum allowable search time;
- and
- partitioning said search face into sub-search-faces if said search time is greater than said maximum allowable search time, and for each of said sub-search-faces, initiating radar scanning;
- wherein said step of determining the number of beams required to cover the search face includes the calculation of
- N
- =
- [
- 1
- +
- 2
-
-
- flr
-
-
- (
- (
- A
- ext
- 2
-
- Δ
-
-
- A
- )
- +
- (
- 1
- 2
- )
- )
- ]
-
- [
- 1
- +
- 2
-
-
- flr
-
-
- (
- (
- E
- ext
- 2
-
- Δ
-
-
- E
- )
- +
- (
- 1
- 2
- )
- )
- ]
- +
- 4
-
- [
- 1
- +
- flr
-
-
- (
- A
- ext
- 2
-
- Δ
-
-
- A
- )
- ]
-
- [
- 1
- +
- flr
-
-
- (
- E
- ext
- 2
-
- Δ
-
-
- E
- )
- ]
- where:
- Aext is half the azimuth extent of the search face;
- Eext is half the elevation extent of the search face;
- ΔA is the azimuthal beam separation at constant elevation;
- ΔA=(β/2)cos α, where β is the beam width and α is equal to ½ the acute angle of the two lines that extend from the center of a radar beam to the points of intersection of the circumference of the beam with the circumference of an adjacent beam;
- ΔE is the elevation separation of the line of centers of the horizontal rows;
- ΔE=(β/2)(1+sin α);
- and
- flr is a floor function that truncates the argument to the highest integer less than the argument.
A system for searching an angular region of a radar search volume, said system comprising:
- a command and decision unit for:
- determining azimuth and elevation extents of a search face of the radar search volume about a cue direction from error information;
- and
- determining an angular extent of each of a plurality of radar beams in azimuth and elevation;
- and
- a radar beam controller for:
- from said angular extents in azimuth and elevation for each radar beam, determining a number of beams required to cover the search face of the search volume;
- determining a dwell time for each of the radar beams given a maximum range;
- taking a product of said number of beams multiplied by the dwell time per beam to obtain a search time;
- comparing said search time with a maximum allowable search time;
- initiating radar scanning over said search face with said number of beams if said search time is less that said maximum allowable search time;
- and
- partitioning said search face into sub-search-faces if said search time is greater than said maximum allowable search time, and for each of said sub-search-faces, initiating radar scanning.
A method for searching a portion of a radar search volume, said method comprising the steps of:
- determining azimuth and elevation extents of a search face of the search volume about the cue direction from error information;
- determining an angular extent of each of a plurality of radar beams in azimuth and elevation;
- from said angular extents in azimuth and elevation for each radar beam, determining a number of beams required to cover the search face of the radar search volume;
- determining a dwell time for each of the radar beams given a maximum search range of said plurality of radar beams;
- obtaining a search time by multiplying said number of beams by the dwell time per beam;
- comparing said search time with a maximum allowable search time;
- initiating radar scanning of the search face if said search time is less than said maximum allowable search time;
- and
- reducing a size of said search face if said search time is greater than said maximum allowable search time, and for said reduced size search face, initiating radar scanning.
Dependencies are inferred from the claim text.