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US 6,388,603 B1Granted
System and method for bistatically determining altitude and slant range to a selected target
AssigneeRaytheon Company
InventorsLawrence M. Frazier, Benjamin G. Lewis
Life of this patent
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Abstract
A bistatic passive radar system is used in conjunction with a host transmitter that is a determinable distance D from the radar system for determining the distance D and for displaying video images of a selected target, the position of the radar system and the position of the transmitter on a display. The invention is characterized by a system and method of using the display to determine the slant range S and the altitude H of the selected target relative to the position of the radar system. Three alternative embodiments of the invention are disclosed.
Claims26
A bistatic passive radar system for use in conjunction with a host transmitter that is a determinable distance D from the radar system, and which includes means for determining the distance D, a display and means for displaying video images of a selected target, the position of the radar system and the position of the transmitter on the display, characterized by
- means for using the display to determine the slant range S and the altitude H of the selected target relative to the position of the radar system.
A bistatic passive radar system for use in conjunction with a host transmitter that is a determinable distance D from the radar system, and which includes means for determining the distance D, a display and means for displaying video images of a selected target, the position of the radar system and the position of the transmitter on the display, characterized by
- the means for displaying the video image of the selected target including means for determining the azimuth angle φ between the extension of a line extending from the radar system through the host transmitter and a line extending from the host transmitter to the selected target;
- means for determining the apparent range Ra from the host transmitter to the selected target;
- and means for computing the corrected range Rc from the host transmitter to the selected target in accordance with the equation:
- R c = ( R a 2 + 2 R a D ) cos θ 2 R a + 2 D ( 1 - cos φ cos θ ) ;
- and by the system comprising
- means for displaying a first cursor on the display extending from the displayed position of the host transmitter to bisect the video image of the selected target;
- means for determining the azimuth angle B between the line of sight from the radar system to the host transmitter and a line extending from the radar system to the selected target;
- means for displaying a second cursor on the display at the angle B from a line extending between the displayed positions of the radar system and the host transmitter, and for extending the length of the second cursor from the displayed position of the radar system to terminate at the first cursor;
- means for determining the horizontal range C from the radar system to the selected target in accordance with the length of the second cursor;
- means for multiplying the quantity cos φ by a quantity cos θ to provide the term cos φ cos θ when computing Rc, wherein θ is a variable angle of elevation from the host transmitter, whereby when θ is the angle of the elevation θc from the host transmitter to the selected target, the video image of the selected target is aligned with the second cursor;
- means for computing the altitude H of the selected target relative to the position of the radar system by using the angle of elevation θc and the value of Rc that is computed when θ equals θc;
- and
- means for computing the slant range S of the selected target relative to the position of the radar system from the computed altitude H and the determined horizontal range C from the radar system to the selected target.
10 more elements
A bistatic passive radar system for use in conjunction with a host transmitter that is a determinable distance D from the radar system, and which includes means for determining the distance D, a display and means for displaying video images of a selected target, the position of radar system and the position of the transmitter on the display, characterized by
- the means for displaying the video image of the selected target includes means for determining the azimuth angle φ between the extension of a line extending from the radar system through the host transmitter and a line extending from the host transmitter to the selected target;
- means for determining the apparent range Ra from the host transmitter to the selected target;
- and means for computing the corrected range Rc from the host transmitter to the selected target in accordance with the equation:
- R c = ( R a 2 + 2 R a D ) cos θ 2 R a + 2 D ( 1 - cos φ cos θ ) ;
- and by the system comprising
- means for displaying a first cursor on the display extending from the displayed position of the host transmitter to bisect the video image of the selected target;
- means for determining the azimuth angle B between the line of sight from the radar system to the host transmitter and a line extending from the radar system to the selected target;
- means for displaying a second cursor on the display at the angle B from a line extending between the displayed positions of the radar system and the host transmitter, and for extending the second cursor from the displayed position of the radar system toward the first cursor;
- means for determining the angle of elevation E from the radar system to the selected target;
- means for multiplying the quantity cos φ by a quantity cos θ to provide the term cos φ cos θ when computing Rc, wherein θ is a variable angle of elevation from the host transmitter, whereby when θ is the angle of the elevation θc from the host transmitter to the selected target, the video image of the selected target is aligned with the second cursor;
- means for computing the altitude H of the selected target relative to the position of the radar system by using the angle of elevation θc and the value of Rc that is computed when θ equals θc;
- and
- means for computing the slant range S of the selected target relative to the position of the radar system by using the computed altitude H and the determined angle of elevation E from the radar system to the selected target.
10 more elements
A method wherein a bistatic passive radar system is used in conjunction with a host transmitter that is a determinable distance D from the radar system, for determining the distance D and for displaying video images of a selected target, the position of the radar system and the position of the transmitter on a display, characterized by the steps of:
- (a) displaying the video image of the selected target by determining the azimuth angle φ between the extension of a line extending from the radar system through the host transmitter and a line extending from the host transmitter to the selected target;
- determining the apparent range Ra from the host transmitter to the selected target;
- and computing the corrected range Rc from the host transmitter to the selected target in accordance with the equation:
- R c = R a 2 + 2 R a D 2 R a + 2 D ( 1 - cos φ cos θ ) ;
- (b) displaying a first cursor on the display extending from the displayed position of the host transmitter to bisect the video image of the selected target:
- (c) determining the azimuth angle B between the line of sight from the radar system to the host transmitted and a line extending from the radar system to the selected target;
- (d) displaying a second cursor on the display at the angle B from a line extending between the displayed positions of the radar system and the host transmitter, and extending the length of the second cursor from the displayed position of the radar system to terminate at the first cursor;
- (e) determining the horizontal range C from the radar system to the selected target in accordance with the length of the second cursor;
- (f) multiplying the quantity cos φ by a quantity cos θ to provide the term cos φ cos θ when computing Rc, wherein θ is a variable angle of elevation from the host transmitter, whereby when θ is the angle of the elevation θc from the host transmitter to the selected target, the video image of the selected target is aligned with the second cursor;
- (g) computing the altitude H of the selected target relative to the position of the radar system by using the angle of elevation θc and the value of Rc that is computed when θ equals θc;
- and
- (h) computing the slant range S of the selected target relative to the position of the radar system by using the computed altitude H and the determined horizontal range C from the radar system to the selected target.
9 more elements
A method wherein a bistatic passive radar system in conjunction with a host transmitter that is a determinable distance D from the radar systems for determining the distance D and for displaying video images of a selected target, the position of the radar system and the position of the transmitter on a display, characterized by the steps of:
- (a) displaying the video image of the selected target by determining the azimuth angle φ between the extension of a line extending from the radar system through the host transmitter to the selected target;
- determining the apparent range Ra from the host transmitter to the selected target;
- and computing the corrected range Rc from the host transmitter to the selected target in accordance with the equation:
- R c = ( 2 R a 2 + 2 R a D ) cos θ 2 R a + 2 D ( 1 - cos φ cos θ ) ;
- (b) displaying a first cursor on the display extending from the displayed position of the host transmitter to bisect the video image of the selected target;
- (c) determining the azimuth angle B between the line of sight from the radar system to the host transmitter and a line extending from the radar system to the selected target;
- (d) displaying a second cursor on the display at the angle B from a line extending between the displayed positions of the radar system and the host transmitter, and for extending the second cursor from the displayed position of the radar system toward the first cursor;
- (e) determining the angle of elevation E from the radar system to the selected target;
- (f) multiplying the quantity cos φ by a quantity cos θ to provide the term cos φ cos θ when computing Rc, wherein θ is a variable angle of elevation from the host transmitter, whereby when θ is the angle of the elevation θc from the host transmitter to the selected target, the video image of the selected target is aligned with the second cursor;
- (g) computing the altitude H of the selected target relative to the position of the radar system by using the angle of elevation θc and the value of Rc that is computed when θ equals θc;
- and
- (h) computing the slant range S of the selected target relative to the position of the radar system by using the computed altitude H and the determined angle of elevation E from the radar system to the selected target.
9 more elements
A bistatic passive radar system for use in conjunction with a host transmitter that is a determinable distance D from the radar system, and which includes means for determining the distance D, a display and means for displaying video images of a selected target, the position of the radar system and the position of the transmitter on the display, characterized by
- means for displaying a first cursor on the display extending from the displayed position of the host transmitter to bisect the video image of the selected target;
- means for determining the azimuth angle B between the line of sight from the radar system to the host transmitter and a line extending from the radar system to the selected target;
- means for displaying a second cursor on the display at the angle B from the line extending between the displayed positions of the radar system and the host transmitter, and for extending the length of the second cursor from the displayed position of the radar system to terminate at the first cursor:
- means for determining the horizontal range C from the radar system to the selected target in accordance with the length of the second cursor;
- means for determining the angle of elevation E from the radar system to the selected target;
- and
- means for computing the slant range S and the altitude H of the selected target relative to the position of the radar system by using the determined horizontal range C from the radar system to the selected target and the determined angle of elevation E from the radar system to the selected target;
- wherein the means for determining the horizontal range C from the radar system to the selected target comprises
- a cursor length control for controlling the length of the second cursor, and
- a cursor length-to-range converter coupled to the cursor length control for providing a horizontal range signal as a function of second cursor length for indicating the horizontal range C from the radar system to the selected target;
- wherein the means for determining the angle of elevation comprises
- a tracking system for tracking the selected target;
- and
- means coupled to the tracking system for providing an E angle signal for indicating the angle of elevation E at which the selected target is tracked;
- and
- wherein the means for computing the slant range and altitude comprises
- a first memory for providing a first signal representative of the tangent of the angle of elevation E in response to receipt of the E angle signal;
- a second memory for providing a second signal representative of the cosine of the angle of elevation E in response to receipt of the E angle signal;
- a multiplier for multiplying the first signal by the horizontal range signal to provide an altitude signal for indicating the altitude H of the selected target;
- and
- a divider for dividing the horizontal range signal to provide a slant range signal for indicating the slant range S from the radar system to the selected target.
18 more elements
A method wherein a bistatic passive radar system is used in conjunction with a host transmitter that is a determinable distance D from the radar system, for determining the distance D and for displaying video images of a selected target, the position of the radar system and the position of the transmitter on a display, characterized by the steps of:
- (a) displaying a first cursor on the display extending from the displayed position of the host transmitter to bisect the video image of the selected target;
- (b) determining the azimuth angle B between the line of sight from the radar system to the host transmitter and a line extending from the radar system to the selected target;
- (c) displaying a second cursor on the display at the angle B from the line extending between the displayed positions of the radar system and the host transmitter, and extending the length of the second cursor from the displayed position of the radar system to terminate at the first cursor;
- (d) determining the horizontal range C from the radar system to the selected target in accordance with the length of the second cursor;
- (e) determining the angle of elevation E from the radar system to the selected target;
- and
- (f) computing the slant range S and the altitude H of the selected target relative to the position of the radar system by using the determined horizontal range C from the radar system to the selected target and the determined angle of elevation E from the radar system to the selected target;
- wherein step (d) comprises the steps of:
- (g) controlling the length of the second cursor;
- and
- (h) providing a horizontal range signal as a function of second cursor length for indicating the horizontal range C from the radar system to the selected target;
- wherein step (e) comprises the steps of:
- (i) tracking the selected target;
- and
- (j) providing an E angle signal for indicating the angle of elevation E at which the selected target is tracked;
- and
- wherein step (f) comprises the steps of:
- (k) providing a first signal representative of the tangent of the angle of elevation E from a first memory in response to receipt of the E angle signal;
- (l) providing a second signal representative of the cosine of the angle of elevation E from a second memory in response to receipt of the E angle signal;
- (m) multiplying the first signal by the horizontal range signal to provide an altitude signal for indicating the altitude H of the selected target;
- and
- (n) dividing the horizontal range signal to provide a slant range signal for indicating the slant range S from the radar system to the selected target.
19 more elements
Dependencies are inferred from the claim text.