US20080074639A1 - Passive determination of ground target location - Google Patents
Passive determination of ground target location Download PDFInfo
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- US20080074639A1 US20080074639A1 US11/472,690 US47269006A US2008074639A1 US 20080074639 A1 US20080074639 A1 US 20080074639A1 US 47269006 A US47269006 A US 47269006A US 2008074639 A1 US2008074639 A1 US 2008074639A1
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- 230000008685 targeting Effects 0.000 claims description 12
- 238000004590 computer program Methods 0.000 claims description 10
- 238000004364 calculation method Methods 0.000 claims description 4
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C3/00—Measuring distances in line of sight; Optical rangefinders
- G01C3/02—Details
- G01C3/06—Use of electric means to obtain final indication
- G01C3/08—Use of electric radiation detectors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
- G01S19/50—Determining position whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
- G01S19/51—Relative positioning
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/16—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using electromagnetic waves other than radio waves
Definitions
- the invention relates generally to navigation and target location systems. More particularly, this invention relates to a passive target identification systems.
- Prior art target location systems exist, which can identify the latitude, longitude and elevation of a distant target using a laser beam that is directed at the target from an observation point, the latitude, longitude and elevation of which is known. If the latitude, longitude and elevation of an observation point are known, the latitude, longitude and elevation of a point in space that is distant from the observation point can be easily determined using simple trigonometric formulae on the azimuth, elevation angle and distance between the observation point and the target.
- Distance to a target point from an observation point can be easily and accurately determined by measuring the time required for a pulse of laser light to traverse the distance between the observation point where a laser is located and the target point.
- Laser beam elevation angle (positive and negative) and the beam's azimuth angle to a target point are also easily determined.
- Prior art target location systems that use a laser or other detectable signal are referred to herein as active target location systems.
- a problem with prior art active target location systems is that laser light or other electromagnetic energy used to locate or mark a target can be detected. Sighting a target using laser light energy therefore announces to the world that the target is being lased. Using a laser to mark a target and/or determine a target's location therefore has drawbacks. Thus, a need exists for a method and apparatus by which coordinates of a target or other destination point in a three-dimensional space can be determined without having to announce to all those concerned that the target is being marked or lased.
- the invention in one implementation encompasses a passive method for locating a distant target from a known location.
- the method is to iteratively determine latitude and longitude coordinates for locations at, around or near a target.
- the latitude and longitude coordinates around the target are determined using a line-of-sight elevation angle between an observation point to the target.
- the observation point is elevated above the ground, which determines a reference point elevation.
- Azimuth angles are also used to calculate latitude and longitude coordinates of the target from the observation point.
- the actual elevation of the terrain immediately above the location they define is read from a digital terrain elevation database or DTED. If the terrain elevation above the calculated latitude and longitude is different than the elevation of the reference point elevation, the reference point elevation is adjusted and the calculations repeated until the reference point elevation matches or substantially matches the elevation of the coordinates of the target, in which case the target's latitude, longitude and elevation are precisely determined. No detectable radiation is needed to mark or locate the target.
- FIG. 1 is a representation of one implementation of a method for passively determining a ground target's location in the simple case where the target is coplanar with a reference point;
- FIGS. 2-5 depict a second implementation of a method for passively determining a ground target's location by iteratively adjusting a reference point elevation until it is determined to be at the same elevation of the target;
- FIG. 6 depicts an apparatus for passively determining a ground target's location.
- FIG. 1 demonstrates a method 10 for passively determining or identifying the location 12 of a ground target 14 from an observation point 16 for the trivial case where the observation point 16 and the target 14 are on the same flat, horizontal plane.
- the observation point 16 is directly above a first reference point 20 by a height or elevation 18 .
- the first reference point 20 will itself have an elevation with respect to sea level. The elevation of the first reference point could of course be greater than or less than or equal to sea level.
- Every point on the Earth's surface 22 can be precisely identified by latitude and longitude coordinates. Since the first reference point 20 is located on the Earth's surface 22 , it is unambiguously identified by latitude and longitude coordinates. Since the observation point 16 is directly above the first reference point 20 by a known elevation 18 , the latitude and longitude of the first reference point 22 is known from the latitude and longitude of the first reference point 22 and the elevation 18 of the first observation point 16 above the first reference point 22 . These three scalars (latitude and longitude of first reference point 22 and elevation of the observation point 18 ) unambiguously identify the observation point 16 .
- a first step of passively determining the location of a remote or distant target 14 is to determine the latitude and longitude of the first reference point 22 , which is depicted in FIG. 1 as being on the Earth's surface 22 .
- a second step of passively determining the location of a remote target 14 is to determine the elevation 18 of the observation point 16 above the first reference point 22 .
- the next step of the method is to determine the line-of-sight elevation angle from the observation point 18 to the ground target 14 .
- an additional step of determining the target location is to determine the azimuth angle from true north to the ground target 14 (not shown in FIG. 1 ).
- azimuth is the angle measured about (i.e., around) the observation point 18 or the first reference point 22 between true north (or other reference point) and a vertical line passing through the center of the ground target 14 .
- Those of ordinary skill in navigation usually measure azimuth angle in a direction that is clockwise from the north point (or other reference point) through 360 degrees.
- FIG. 1 is considered to depict a trivial or simple case of locating a remote target 14 because FIG. 1 depicts the target 14 and the first reference point 20 to be on a flat plane in which the Earth's curvature is ignored.
- the tangent of the line of sight elevation angle A is determined by the quotient of the horizontal distance (along the x-axis) between the first reference point 22 and the elevation 18 of the observation point 18 .
- the horizontal distance (along the x-axis) between the first reference point 22 and the target 14 is therefore determined by dividing the elevation distance 18 by the tangent of the elevation angle ‘A.’
- the latitude and longitude coordinates of the target 14 can be determined from the horizontal distance to the target 14 from the first reference point 20 and by dividing the distance between the first reference point 22 and the target 14 by either the sine or cosine of the azimuth angle.
- the line of sight distance 22 between the target 14 and the observation point 16 can also be determined by dividing the elevation 18 of the observation point 16 by the cosine of the angle A.
- FIGS. 2-5 depict steps of a method 10 for passively determining or identifying the location 12 of a ground target 14 from an observation point 16 in the general case where the elevation of the target 14 is unknown.
- a terrain database of actual elevations of points around the target 14 wherein there are stored, the actual elevation of the Earth's surface at various latitude and longitude coordinates.
- a database wherein elevations of latitude and longitude coordinates are stored is referred to or known as a digital terrain elevations database or DTED.
- a DTED which is not shown in the figures, is a database of latitude and longitude coordinates throughout a geographic region (or world wide) and the ground's elevation at each latitude and longitude coordinate pair.
- the observation point 16 of FIG. 2 is directly above a first reference point 20 having an elevation 21 .
- the observation point 16 is directly above the first reference point 20 at a known elevation 18 above the elevation 21 of the Earth's surface.
- the target 14 is shown to be on a mountainside or a hillside, at an unknown elevation ‘E’ above the elevation 21 of the first reference point 18 .
- the target 14 in FIG. 2 is at an unknown elevation E above the first reference point 18 , its latitude and longitude cannot be reliably determined as in the simple case shown in FIG. 1 because the trigonometric relationships used to locate the target 14 in the simple case described with respect to FIG. 1 , work only with right triangles.
- the location of the target 14 i.e., its latitude, longitude and elevation, are determined by iteratively as described below.
- the method of passively determining the target's location relies on a topographic map or a digital terrain elevation database or DTED (not shown), which contains the actual elevation 26 above sea level of latitude and longitude coordinates all around the target 14 .
- the DTED includes the elevation of the point directly above the calculated target location 15 , which is referred to herein as the calculated target elevation 24 as shown in FIG. 2 .
- the elevation of the calculated target location 15 is the actual elevation of the point directly above the calculated target elevation 15 , which point is determined from the elevation 18 , the tangent of the line-of-sight inclination angle A and the azimuth angle, which is not shown in the figures for clarity.
- the next step of the general case method for passively determining a ground target's location is to determine the arithmetic difference between the calculated target location 24 and the first reference point elevation 21 .
- the first reference point elevation 21 is the elevation of the first reference point 20 .
- elevations of the various points used in the method are values with respect to sea level. So long as all elevations are with respect to sea level, the arithmetic difference between the first reference point elevation 21 and the calculated target elevation 24 will yield the elevation difference identified in FIG. 2 by reference numeral 26 .
- the calculated target elevation 24 is the first reference point elevation 21 . Therefore, the latitude and longitude coordinates of the calculated target location 15 can be determined using the simple case methodology described above with regard to FIG. 1 because the angle between the distance 18 and a line between the first reference point 18 and the target 14 is a right angle and conventional trigonometric relationships apply.
- the calculated target elevation 24 and the first reference point elevation 21 are the same, the elevation of the target 14 is known.
- the latitude and longitude coordinates of the calculated target location 15 will not correspond to the actual latitude and longitude coordinates of the target 14 .
- the trigonometric relationships used to calculate the latitude and longitude (and elevation) coordinates from the first reference point 20 , the line-of-sight elevation angle A and the azimuth apply only to right triangles.
- additional steps are required to passively determine the location of the target 14 when the target 14 is at an unknown elevation that happens to be different than the first reference point elevation 21 .
- the next step of the method of passively determining the location of the target 14 is shown in FIG. 3 .
- the next step of the method is to increment (or decrement in an alternate embodiment) the first reference point elevation 21 by a predetermined amount, which defines a second reference point 20 ′ (directly above the first reference point 20 ) and a second reference point elevation 21 ′.
- the method of passively locating the target 14 determines a 2 nd calculated target location 15 ′ latitude and longitude coordinates using the method described above with respect to FIG. 1 .
- the latitude and longitude coordinates of the 2 nd calculated target location 15 ′ will of course yield from the DTED, an elevation, which is shown in FIG. 3 and referred to herein as the 2 nd calculated target elevation 24 ′.
- the next step of the method is to calculate the elevation difference between the 2 nd nd calculated target elevation 24 ′ (as read from the DTED) and the second reference point elevation 21 ′. If the elevation between these two points is zero, the 2 nd calculated target elevation 24 ′ is the same as the second reference point elevation 21 ′.
- the trigonometric relationships used in the simple method described with respect to FIG. 1 will apply in which case, the latitude and longitude coordinates of the second calculated target location 15 ′ correspond to the latitude and longitude of the target 14 and elevation of the target 14 can be determined to be the 2 nd nd calculated target elevation 24 ′.
- the method of passively determining the location of the target 14 increments the second reference point elevation 21 ′ to define a third reference point elevation 21 ′′.
- the second reference point elevation is incremented by the aforementioned predetermined amount although alternate embodiments of the method contemplate incrementing (and/or decrementing the second reference point elevation by other amounts). Incrementing the second reference point elevation defines a third reference point 20 ′′ (directly above the first reference point 20 ) at a third reference point elevation 21 ′′.
- the method of passively locating the target 14 determines the latitude and longitude coordinates of a 3 rd calculated target location 15 ′′ using the method described above with respect to FIG. 1 .
- the latitude and longitude coordinates of the 3 rd calculated target location 15 ′′ are calculated from the line-of-sight elevation angle A and the azimuth angle, the coordinates are used as an index into the DTED from which an actual elevation of these coordinates is read and used to determine the 3 rd calculated target elevation 24 ′′.
- the next step of the method is to calculate the elevation difference between the 3 rd calculated target elevation 24 ′′ and the third reference point elevation 21 ′′. If the elevation between these two points is zero, the elevation of the 3 rd calculated target elevation is the same as the third reference point elevation 21 ′.
- the trigonometric relationships used in the simple method described with respect to FIG. 1 will apply.
- the latitude and longitude coordinates of the target 14 can be determined from the elevation of the observation point 16 above the third reference point elevation 21 ′ the line-of-sight inclination angle ‘A’ and an azimuth angle for the target 14 .
- the method of passively determining the location of the target 14 increments the second reference point elevation 21 ′′ yet again to yield a third reference point elevation 21 ′′′. Incrementing the second reference point elevation defines a fourth reference point 20 ′′′ directly above the first reference point 20 and a fourth reference point elevation 21 ′′′. After defining a fourth reference point elevation 21 ′′′, the method of passively locating the target 14 determines the latitude and longitude coordinates of a 4 the calculated target location 15 ′′′ using the method described above with respect to FIG. 1 .
- the latitude and longitude coordinates of the 4 th calculated target location 15 ′′′ are used as an index into the DTED from which an elevation of these coordinates is read and used to determine the 4 th calculated target elevation 24 ′′′.
- the next step of the method is to calculate the elevation difference between the 4 th calculated target elevation 24 ′′′ and the 4 th reference point elevation 21 ′′′. If the elevation between these two points is zero, as shown in FIG. 5 , the elevation of the 4 th calculated target elevation 24 ′′′ is the same as the 4 th reference point elevation 21 ′′′.
- the elevation of the target 14 is determined and the trigonometric relationships used in the simple method described with respect to FIG. 1 will apply to determine the latitude and longitude coordinates of the target 14 from the elevation of the observation point 16 above the fourth reference point elevation 21 ′′′ the line-of-sight inclination angle ‘A’ and an azimuth angle for the target 14 .
- an alternate embodiment of the method is to adjust the reference point elevation 21 by an amount equal to the difference between the calculated target elevation 24 and the reference point elevation.
- Such an alternate embodiment may be more computationally efficient than the method described above if the elevation differences are initially large, in which case a number of iterations required by the aforementioned method might be eliminated.
- the apparatus 50 includes a computer or CPU 52 that is operatively coupled to a storage device 54 wherein computer program instructions are stored, which when executed cause the CPU to send signals and/or information to, and receive signals and/or information from, a camera target sighting system 56 , a host attitude system 58 , a host navigation system 60 , controls and displays for an operator 62 , a terrain data base 66 , a solution storage device 64 and a radio 66 .
- the storage device 54 stores program instructions, which when executed cause the CPU to calculate the location of a ground target using the method described above.
- the storage device 54 can be implemented using a variety of semiconductor storage devices such as static and/or dynamic random access memory (RAM), ROM, EPROM and/or EPROM devices, as they are known in the art.
- RAM static and/or dynamic random access memory
- ROM read-only memory
- EPROM EPROM
- EPROM electrically erasable programmable read-only memory
- the CPU determines the location of the system 50 from a host navigation system 60 , the accuracy of which is important because the performance or accuracy of the method described above is dependent on the accuracy of the initial or starting location of an observation point.
- the host navigation system 60 provides real time latitude and longitude data of where an observation point 16 or observation aircraft is located.
- Examples of a host navigation system 60 include but are not limited to, a high-accuracy or an aided differential global positioning system or an inertial navigation system.
- the CPU 52 also communicates with a host attitude system 58 , which can provide inertial navigation but which also provides a heading reference and pitch and roll angles, of an aircraft or other vehicle in which the system is located.
- a host attitude system 58 which can provide inertial navigation but which also provides a heading reference and pitch and roll angles, of an aircraft or other vehicle in which the system is located.
- a camera targeting system 56 coupled to the CPU sends data to the CPU 52 that indicates or represents the aforementioned angle of inclination between an observation point 16 and a ground target 14 .
- Examples of a camera targeting system 56 include a color, black & white or infrared camera that can be directed to a target and which provides data to the CPU 52 that represents either absolute (with respect to the reference plane) or relative angles to a ground target 14 .
- Other examples of a camera targeting system include a helmet mounted display (HMD) or a Target Sighting System (TSS).
- a terrain database 66 coupled to the CPU 52 is implemented using devices such as those used to implement the storage device 54 .
- the terrain database 66 stores representations of the height above sea-level for geo-registered points (having latitude and longitudinal coordinates) in a grid of points.
- the terrain database 66 stores a geoidal height model database.
- Solutions that are computed by the CPU i.e., locations of ground targets that have been passively computed, are stored in a solution storage device 64 coupled to the CPU 52 .
- the identity of ground targets, which can include images of the targets, and their locations, which are stored in the solution storage 64 can be transmitted from the system 50 using a radio 66 that is also coupled to the CPU 52 .
- target identity and location can be transmitted to distant centers in real time.
- the controls and user interfaces 62 for the system 50 are also coupled to the CPU 52 .
- the controls and user interfaces 62 include various displays and controls by which an operator can control the camera targeting system 56 and/or the transmission of target image and location data from the radio 66 .
- the efficacy of the method and the accuracy of its results will also depend on how the latitude and longitude coordinates of the reference points are determined.
- Latitude and longitude coordinates can be determined from printed maps, inertial navigational systems but most accurately from the global positioning system.
- the step of adjusting the first reference point elevation 21 can include numerous variations. If surrounding terrain is generally smooth or has gently rolling hills, the first increment of the first reference point elevation 21 could be specified to be relatively large, if the elevation difference between the first calculated target elevation 24 and the first reference 21 is large, which would correspond to a great distance between the reference point 20 and the first calculated target location. Conversely, the step of adjusting the first reference point elevation 21 could be specified to be very small, in mountainous areas of if a very accurate determination of the target's location was desired.
- the step of determining the difference in elevation between a calculated target elevation and a reference point elevation need not be exactly zero. Differences in elevation between a calculated target elevation and a reference point elevation can be non-zero values to acknowledge the fact that minor variations in terrain around the target 14 may make it difficult to iteratively determine the exact elevation of the target 14 .
- a computer As described above, the general case of passively determining the location of a target requires a digital terrain elevation database or DTED.
- a computer that performs the calculations above is preferably coupled to a DTED so that it can read calculated target elevations as needed.
Abstract
Description
- The invention relates generally to navigation and target location systems. More particularly, this invention relates to a passive target identification systems.
- Prior art target location systems exist, which can identify the latitude, longitude and elevation of a distant target using a laser beam that is directed at the target from an observation point, the latitude, longitude and elevation of which is known. If the latitude, longitude and elevation of an observation point are known, the latitude, longitude and elevation of a point in space that is distant from the observation point can be easily determined using simple trigonometric formulae on the azimuth, elevation angle and distance between the observation point and the target.
- Distance to a target point from an observation point can be easily and accurately determined by measuring the time required for a pulse of laser light to traverse the distance between the observation point where a laser is located and the target point. Laser beam elevation angle (positive and negative) and the beam's azimuth angle to a target point are also easily determined. Prior art target location systems that use a laser or other detectable signal are referred to herein as active target location systems.
- A problem with prior art active target location systems is that laser light or other electromagnetic energy used to locate or mark a target can be detected. Sighting a target using laser light energy therefore announces to the world that the target is being lased. Using a laser to mark a target and/or determine a target's location therefore has drawbacks. Thus, a need exists for a method and apparatus by which coordinates of a target or other destination point in a three-dimensional space can be determined without having to announce to all those concerned that the target is being marked or lased.
- The invention in one implementation encompasses a passive method for locating a distant target from a known location. The method is to iteratively determine latitude and longitude coordinates for locations at, around or near a target. The latitude and longitude coordinates around the target are determined using a line-of-sight elevation angle between an observation point to the target. The observation point is elevated above the ground, which determines a reference point elevation. Azimuth angles are also used to calculate latitude and longitude coordinates of the target from the observation point.
- When latitude and longitude coordinates are first determined, the actual elevation of the terrain immediately above the location they define is read from a digital terrain elevation database or DTED. If the terrain elevation above the calculated latitude and longitude is different than the elevation of the reference point elevation, the reference point elevation is adjusted and the calculations repeated until the reference point elevation matches or substantially matches the elevation of the coordinates of the target, in which case the target's latitude, longitude and elevation are precisely determined. No detectable radiation is needed to mark or locate the target.
- Features of exemplary implementations of the invention will become apparent from the description, the claims, and the accompanying drawings in which:
-
FIG. 1 is a representation of one implementation of a method for passively determining a ground target's location in the simple case where the target is coplanar with a reference point; -
FIGS. 2-5 depict a second implementation of a method for passively determining a ground target's location by iteratively adjusting a reference point elevation until it is determined to be at the same elevation of the target; and -
FIG. 6 depicts an apparatus for passively determining a ground target's location. -
FIG. 1 demonstrates a method 10 for passively determining or identifying the location 12 of aground target 14 from anobservation point 16 for the trivial case where theobservation point 16 and thetarget 14 are on the same flat, horizontal plane. As shown in the figure, theobservation point 16 is directly above afirst reference point 20 by a height orelevation 18. As is also known, thefirst reference point 20 will itself have an elevation with respect to sea level. The elevation of the first reference point could of course be greater than or less than or equal to sea level. - It is well known that every point on the Earth's
surface 22 can be precisely identified by latitude and longitude coordinates. Since thefirst reference point 20 is located on the Earth'ssurface 22, it is unambiguously identified by latitude and longitude coordinates. Since theobservation point 16 is directly above thefirst reference point 20 by a knownelevation 18, the latitude and longitude of thefirst reference point 22 is known from the latitude and longitude of thefirst reference point 22 and theelevation 18 of thefirst observation point 16 above thefirst reference point 22. These three scalars (latitude and longitude offirst reference point 22 and elevation of the observation point 18) unambiguously identify theobservation point 16. - In light of the foregoing, a first step of passively determining the location of a remote or
distant target 14 is to determine the latitude and longitude of thefirst reference point 22, which is depicted inFIG. 1 as being on the Earth'ssurface 22. A second step of passively determining the location of aremote target 14 is to determine theelevation 18 of theobservation point 16 above thefirst reference point 22. - After the
observation point 18elevation 22 is determined, the next step of the method is to determine the line-of-sight elevation angle from theobservation point 18 to theground target 14. In addition to determining the line-of-sight elevation from theobservation point 18 to thetarget 14, an additional step of determining the target location is to determine the azimuth angle from true north to the ground target 14 (not shown inFIG. 1 ). As used herein, azimuth is the angle measured about (i.e., around) theobservation point 18 or thefirst reference point 22 between true north (or other reference point) and a vertical line passing through the center of theground target 14. Those of ordinary skill in navigation usually measure azimuth angle in a direction that is clockwise from the north point (or other reference point) through 360 degrees. - Once the
elevation 18 of theobservation point 16 is known and the line-of-sight elevation angle and azimuth are known, latitude and longitude coordinates of theground target 14 can be determined in the trivial case shown inFIG. 1 by using basic trigonometry.FIG. 1 is considered to depict a trivial or simple case of locating aremote target 14 becauseFIG. 1 depicts thetarget 14 and thefirst reference point 20 to be on a flat plane in which the Earth's curvature is ignored. - In the simple case shown in
FIG. 1 , the tangent of the line of sight elevation angle A, is determined by the quotient of the horizontal distance (along the x-axis) between thefirst reference point 22 and theelevation 18 of theobservation point 18. The horizontal distance (along the x-axis) between thefirst reference point 22 and thetarget 14 is therefore determined by dividing theelevation distance 18 by the tangent of the elevation angle ‘A.’ - Once the distance between the
first reference point 22 and thetarget 14 is known, the latitude and longitude coordinates of thetarget 14 can be determined from the horizontal distance to thetarget 14 from thefirst reference point 20 and by dividing the distance between thefirst reference point 22 and thetarget 14 by either the sine or cosine of the azimuth angle. - It should be noted that the line of
sight distance 22 between thetarget 14 and theobservation point 16 can also be determined by dividing theelevation 18 of theobservation point 16 by the cosine of the angle A. -
FIGS. 2-5 depict steps of a method 10 for passively determining or identifying the location 12 of aground target 14 from anobservation point 16 in the general case where the elevation of thetarget 14 is unknown. Key to the general case method, however, is a terrain database of actual elevations of points around thetarget 14 wherein there are stored, the actual elevation of the Earth's surface at various latitude and longitude coordinates. In some circles, a database wherein elevations of latitude and longitude coordinates are stored is referred to or known as a digital terrain elevations database or DTED. A DTED, which is not shown in the figures, is a database of latitude and longitude coordinates throughout a geographic region (or world wide) and the ground's elevation at each latitude and longitude coordinate pair. - As with the simple case shown in
FIG. 1 , theobservation point 16 ofFIG. 2 is directly above afirst reference point 20 having anelevation 21. Theobservation point 16 is directly above thefirst reference point 20 at aknown elevation 18 above theelevation 21 of the Earth's surface. Thetarget 14, however, is shown to be on a mountainside or a hillside, at an unknown elevation ‘E’ above theelevation 21 of thefirst reference point 18. Because thetarget 14 inFIG. 2 is at an unknown elevation E above thefirst reference point 18, its latitude and longitude cannot be reliably determined as in the simple case shown inFIG. 1 because the trigonometric relationships used to locate thetarget 14 in the simple case described with respect toFIG. 1 , work only with right triangles. The location of thetarget 14, i.e., its latitude, longitude and elevation, are determined by iteratively as described below. - In the general case of passively determining the location of a target shown in
FIG. 2 , when thetarget 14 is at an unknown elevation, simply dividing theelevation distance 18 by the tangent of the line-of-sight angle ‘A’ yields an incorrect result for the distance between thefirst observation point 20 and thetarget 14. Dividing theelevation 18, by the tangent of the observation point line-of-sight angle “A” yields a distance to the point identified inFIG. 2 byreference numeral 15, which point is referred to herein as the calculatedtarget location 15 and which is well beyond the actual distance of thetarget 14 from thefirst reference point 20. - In order to passively determine a target's location when the
target 14 is at an unknown elevation, the method of passively determining the target's location relies on a topographic map or a digital terrain elevation database or DTED (not shown), which contains theactual elevation 26 above sea level of latitude and longitude coordinates all around thetarget 14. The DTED includes the elevation of the point directly above the calculatedtarget location 15, which is referred to herein as the calculatedtarget elevation 24 as shown inFIG. 2 . The elevation of the calculatedtarget location 15 is the actual elevation of the point directly above the calculatedtarget elevation 15, which point is determined from theelevation 18, the tangent of the line-of-sight inclination angle A and the azimuth angle, which is not shown in the figures for clarity. - Having determined the calculated
target elevation 24 by reading it's elevation from a DTED using the latitude and longitude of the calculatedtarget location 15, the next step of the general case method for passively determining a ground target's location is to determine the arithmetic difference between the calculatedtarget location 24 and the firstreference point elevation 21. InFIG. 2 , the firstreference point elevation 21 is the elevation of thefirst reference point 20. - In one embodiment, elevations of the various points used in the method are values with respect to sea level. So long as all elevations are with respect to sea level, the arithmetic difference between the first
reference point elevation 21 and thecalculated target elevation 24 will yield the elevation difference identified inFIG. 2 byreference numeral 26. - If the elevation difference between the first
reference point elevation 21 and thecalculated target elevation 24 is zero, thecalculated target elevation 24 is the firstreference point elevation 21. Therefore, the latitude and longitude coordinates of the calculatedtarget location 15 can be determined using the simple case methodology described above with regard toFIG. 1 because the angle between thedistance 18 and a line between thefirst reference point 18 and thetarget 14 is a right angle and conventional trigonometric relationships apply. When thecalculated target elevation 24 and the firstreference point elevation 21 are the same, the elevation of thetarget 14 is known. - If the elevation difference between the first
reference point elevation 21 and the firstcalculated target elevation 24 is non-zero as shown inFIG. 2 , the latitude and longitude coordinates of the calculatedtarget location 15 will not correspond to the actual latitude and longitude coordinates of thetarget 14. This is because the trigonometric relationships used to calculate the latitude and longitude (and elevation) coordinates from thefirst reference point 20, the line-of-sight elevation angle A and the azimuth, apply only to right triangles. Thus, additional steps are required to passively determine the location of thetarget 14 when thetarget 14 is at an unknown elevation that happens to be different than the firstreference point elevation 21. - If the elevation difference between the first
reference point elevation 21 and the firstcalculated target elevation 24 is non-zero as shown inFIG. 2 , the next step of the method of passively determining the location of thetarget 14 is shown inFIG. 3 . - Referring now to
FIG. 3 , the next step of the method is to increment (or decrement in an alternate embodiment) the firstreference point elevation 21 by a predetermined amount, which defines asecond reference point 20′ (directly above the first reference point 20) and a secondreference point elevation 21′. After defining asecond reference point 20′ and a secondreference point elevation 21, the method of passively locating thetarget 14 determines a 2nd calculatedtarget location 15′ latitude and longitude coordinates using the method described above with respect toFIG. 1 . As shown inFIG. 3 , the latitude and longitude coordinates of the 2nd calculatedtarget location 15′ will of course yield from the DTED, an elevation, which is shown inFIG. 3 and referred to herein as the 2ndcalculated target elevation 24′. - After the 2nd nd calculated
target elevation 24′ is determined, the next step of the method is to calculate the elevation difference between the 2nd nd calculatedtarget elevation 24′ (as read from the DTED) and the secondreference point elevation 21′. If the elevation between these two points is zero, the 2ndcalculated target elevation 24′ is the same as the secondreference point elevation 21′. The trigonometric relationships used in the simple method described with respect toFIG. 1 will apply in which case, the latitude and longitude coordinates of the secondcalculated target location 15′ correspond to the latitude and longitude of thetarget 14 and elevation of thetarget 14 can be determined to be the 2ndnd calculatedtarget elevation 24′. - Referring now to
FIG. 4 , if the elevation difference between the secondreference point elevation 21′ and the 2ndnd calculatedtarget elevation 24′ is non-zero, as shown inFIG. 3 , the method of passively determining the location of thetarget 14 increments the secondreference point elevation 21′ to define a thirdreference point elevation 21″. In one embodiment, the second reference point elevation is incremented by the aforementioned predetermined amount although alternate embodiments of the method contemplate incrementing (and/or decrementing the second reference point elevation by other amounts). Incrementing the second reference point elevation defines athird reference point 20″ (directly above the first reference point 20) at a thirdreference point elevation 21″. After defining athird reference point 20″ with a thirdreference point elevation 21″, the method of passively locating thetarget 14 determines the latitude and longitude coordinates of a 3rd calculatedtarget location 15″ using the method described above with respect toFIG. 1 . - Once the latitude and longitude coordinates of the 3rd calculated
target location 15″ are calculated from the line-of-sight elevation angle A and the azimuth angle, the coordinates are used as an index into the DTED from which an actual elevation of these coordinates is read and used to determine the 3rdcalculated target elevation 24″. After the 3rdcalculated target elevation 24″ is determined from the DTED, the next step of the method is to calculate the elevation difference between the 3rdcalculated target elevation 24″ and the thirdreference point elevation 21″. If the elevation between these two points is zero, the elevation of the 3rd calculated target elevation is the same as the thirdreference point elevation 21′. The trigonometric relationships used in the simple method described with respect toFIG. 1 will apply. The latitude and longitude coordinates of thetarget 14 can be determined from the elevation of theobservation point 16 above the thirdreference point elevation 21′ the line-of-sight inclination angle ‘A’ and an azimuth angle for thetarget 14. - Referring now to
FIG. 5 , since the elevation difference between the secondreference point elevation 21″ the 2ndcalculated target elevation 24′ was non-zero as shown inFIG. 3 , the method of passively determining the location of thetarget 14 increments the secondreference point elevation 21″ yet again to yield a thirdreference point elevation 21′″. Incrementing the second reference point elevation defines afourth reference point 20′″ directly above thefirst reference point 20 and a fourthreference point elevation 21′″. After defining a fourthreference point elevation 21′″, the method of passively locating thetarget 14 determines the latitude and longitude coordinates of a 4the calculatedtarget location 15′″ using the method described above with respect toFIG. 1 . - The latitude and longitude coordinates of the 4th calculated
target location 15′″ are used as an index into the DTED from which an elevation of these coordinates is read and used to determine the 4thcalculated target elevation 24′″. After the 4thcalculated target elevation 24′″ is determined from the DTED, the next step of the method is to calculate the elevation difference between the 4thcalculated target elevation 24′″ and the 4threference point elevation 21′″. If the elevation between these two points is zero, as shown inFIG. 5 , the elevation of the 4thcalculated target elevation 24′″ is the same as the 4threference point elevation 21′″. The elevation of thetarget 14 is determined and the trigonometric relationships used in the simple method described with respect toFIG. 1 will apply to determine the latitude and longitude coordinates of thetarget 14 from the elevation of theobservation point 16 above the fourthreference point elevation 21′″ the line-of-sight inclination angle ‘A’ and an azimuth angle for thetarget 14. - While the embodiment described above adjusted the reference point elevation by one or more fixed amounts in each iteration, an alternate embodiment of the method is to adjust the
reference point elevation 21 by an amount equal to the difference between thecalculated target elevation 24 and the reference point elevation. Such an alternate embodiment may be more computationally efficient than the method described above if the elevation differences are initially large, in which case a number of iterations required by the aforementioned method might be eliminated. - Referring now to
FIG. 6 , there is shown a block diagram of anapparatus 50 for passively determining a ground target's location. Theapparatus 50 includes a computer orCPU 52 that is operatively coupled to astorage device 54 wherein computer program instructions are stored, which when executed cause the CPU to send signals and/or information to, and receive signals and/or information from, a cameratarget sighting system 56, ahost attitude system 58, ahost navigation system 60, controls and displays for anoperator 62, aterrain data base 66, asolution storage device 64 and aradio 66. - The
storage device 54 stores program instructions, which when executed cause the CPU to calculate the location of a ground target using the method described above. Thestorage device 54 can be implemented using a variety of semiconductor storage devices such as static and/or dynamic random access memory (RAM), ROM, EPROM and/or EPROM devices, as they are known in the art. Thestorage device 54 can also be implemented using magnetic and/or optical disks. - In the course of executing program instructions stored in the
storage device 54, the CPU determines the location of thesystem 50 from ahost navigation system 60, the accuracy of which is important because the performance or accuracy of the method described above is dependent on the accuracy of the initial or starting location of an observation point. The more accurate theobservation point 16 location is, the more accurate will be the determinedlocation ground target 14. - In one embodiment, the
host navigation system 60 provides real time latitude and longitude data of where anobservation point 16 or observation aircraft is located. Examples of ahost navigation system 60 include but are not limited to, a high-accuracy or an aided differential global positioning system or an inertial navigation system. - The
CPU 52 also communicates with ahost attitude system 58, which can provide inertial navigation but which also provides a heading reference and pitch and roll angles, of an aircraft or other vehicle in which the system is located. - A
camera targeting system 56 coupled to the CPU sends data to theCPU 52 that indicates or represents the aforementioned angle of inclination between anobservation point 16 and aground target 14. Examples of acamera targeting system 56 include a color, black & white or infrared camera that can be directed to a target and which provides data to theCPU 52 that represents either absolute (with respect to the reference plane) or relative angles to aground target 14. Other examples of a camera targeting system include a helmet mounted display (HMD) or a Target Sighting System (TSS). - A
terrain database 66 coupled to theCPU 52 is implemented using devices such as those used to implement thestorage device 54. Theterrain database 66 stores representations of the height above sea-level for geo-registered points (having latitude and longitudinal coordinates) in a grid of points. In an alternate embodiment, theterrain database 66 stores a geoidal height model database. - Solutions that are computed by the CPU, i.e., locations of ground targets that have been passively computed, are stored in a
solution storage device 64 coupled to theCPU 52. The identity of ground targets, which can include images of the targets, and their locations, which are stored in thesolution storage 64, can be transmitted from thesystem 50 using aradio 66 that is also coupled to theCPU 52. Thus, target identity and location can be transmitted to distant centers in real time. - Finally, the controls and
user interfaces 62 for thesystem 50 are also coupled to theCPU 52. The controls anduser interfaces 62 include various displays and controls by which an operator can control thecamera targeting system 56 and/or the transmission of target image and location data from theradio 66. - Those of ordinary skill in the navigation arts will recognize that passively locating a target, avoids having to use a laser or other energy source to mark or identify a target. Thus, announcing the fixation of the target by irradiating it with detectable energy is avoided and announcing the location of a person targeting a location by irradiating it is also avoided.
- Those of ordinary skill in the art will also recognize that the efficacy of the method described above and the accuracy of its results directly depend on the line-of-sight angle measurement accuracy and the elevation measurement accuracy. Various methods and apparatus exist for measuring line-of-sight angles. Some of these devices include mounted camera, helmet mounted displays (HMD) used in prior art weapons aiming systems and prior art Target Sighting Systems (TSS).
- The efficacy of the method and the accuracy of its results will also depend on how the latitude and longitude coordinates of the reference points are determined. Latitude and longitude coordinates can be determined from printed maps, inertial navigational systems but most accurately from the global positioning system.
- Those of ordinary skill in the art will also recognize that the step of adjusting the first
reference point elevation 21 can include numerous variations. If surrounding terrain is generally smooth or has gently rolling hills, the first increment of the firstreference point elevation 21 could be specified to be relatively large, if the elevation difference between the firstcalculated target elevation 24 and thefirst reference 21 is large, which would correspond to a great distance between thereference point 20 and the first calculated target location. Conversely, the step of adjusting the firstreference point elevation 21 could be specified to be very small, in mountainous areas of if a very accurate determination of the target's location was desired. - It should be noted that the step of determining the difference in elevation between a calculated target elevation and a reference point elevation need not be exactly zero. Differences in elevation between a calculated target elevation and a reference point elevation can be non-zero values to acknowledge the fact that minor variations in terrain around the
target 14 may make it difficult to iteratively determine the exact elevation of thetarget 14. - Those of ordinary skill in the art will recognize that the method described above is best carried out by a computer. As described above, the general case of passively determining the location of a target requires a digital terrain elevation database or DTED. A computer that performs the calculations above is preferably coupled to a DTED so that it can read calculated target elevations as needed.
- Finally, it should be noted that the steps described herein are just examples. The steps may be performed in a differing order, or steps may be added, deleted, or modified.
- Although an example of the invention have been described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.
Claims (22)
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Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4954837A (en) * | 1989-07-20 | 1990-09-04 | Harris Corporation | Terrain aided passive range estimation |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2368042A1 (en) * | 1976-10-18 | 1978-05-12 | Sfim | METHOD AND DEVICE FOR CORRECTING THE POINTING OF AN OPTICAL ILLUMINATOR ON A TARGETED TARGET. |
US5568152A (en) * | 1994-02-04 | 1996-10-22 | Trimble Navigation Limited | Integrated image transfer for remote target location |
US5969676A (en) * | 1997-09-30 | 1999-10-19 | Honeywell Inc. | Radio frequency interferometer and laser rangefinder/destination base targeting system |
-
2006
- 2006-06-22 US US11/472,690 patent/US7359038B1/en active Active
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4954837A (en) * | 1989-07-20 | 1990-09-04 | Harris Corporation | Terrain aided passive range estimation |
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