Passive target data acquisition method and system

• US 7,107,179 B2
• Filed: 08/17/2005
• Issued: 09/12/2006
• Est. Priority Date: 03/02/2003
• Status: Active Grant

• Current Assignee: Tomer Malchi, Yaniv Malchi
• Original Assignee: Tomer Malchi, Yaniv Malchi
• Inventors: Malchi, Yaniv, Malchi, Tomer
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Washburn, Douglas N.
• Application Number:
  US11/205,697
• Publication Number:
  US 20050273254A1
• Time in Patent Office: 391 Days
• Field of Search: 702/92, 702/150, 702/152, 702/153
• US Class Current: 702/152
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

Method and passive target data acquisition system operable continuously from an observation point for passively sighting a target and acquiring the target on a DTM for passively deriving target data and associated information without emitting radiations prone to detection. The location of the target is shown on a display, and so is an error-area due to measurement inaccuracies. When terrain topography causes the system to indicate more than one error-area, the target and the accompanying error-areas are displayed. The distance between error-areas indicates dead terrain zones. A north finding procedure provides accurate north direction correction to rough north readings taken with a coarse north-indicating device. The system is small enough for integration with handheld personal binoculars, and is operable from static and mobile observation points, possibly on a stabilized platform, on land, at sea, in the air, and in space.

Claims

1. A method using a passive target data acquisition system (PTAS) operative from an observation point for passively sighting a target, the PTAS having:

passive sighting means coupled to a navigation device and to azimuth and elevation angle measuring devices, a computer module operatively coupled sighting means, and to a display, to a digital terrain model DTM database, to the the method comprising the steps of;

measuring location data of the observation point, and azimuth and elevation angle data to the target, and feeding measured data to the computer module and presenting on the display both the observation point and the target on a corresponding DTM surface derived from the DTM database, the method comprising the steps of;

directing a vector toward the target and defining an envelope surrounding the vector originating at the observation point, and an envelope mantle distanced away from the vector proportionally to errors of measurement, running a PTAS computer program on the computer module for calculating intersection points of the vector and of the envelope with the DTM surface, and presenting the intersection points and associated information on the display, whereby target data is acquired passively to avoid emission of radiations.

2. The method according to claim 1, including:

running the PTAS computer program to derive a distance separating between intersection points selected on the DTM surface, and

deriving a range measurement separating the observation point from the target.

3. The method according to claim 1, including:

running the PTAS computer program for deriving target data including target range and target location.

4. The method according to claim 1, including:

operating uninterruptedly for continuously deriving measured and calculated data, and

operating uninterruptedly to continuously provide target range, target location data, and associated information.

5. The method according to claim 1, including:

detecting existence of dead zone(s) distributed along the vector, between the observation point and the target, and

mapping the dead zone(s) on the display.

6. The method according to claim 1, including:

feeding the PTAS computer program with selected data including position location, line of sight (LOS) vector length, azimuth and elevation angles, and running the PTAS computer module according to the selected data to display dead zone(s) of terrain and associated information.

7. The method according to claim 1, including:

sighting a target from an observation point located above the DTM surface and disposed on either one of both an airborne platform and a space-borne platform.

8. The method according to claim 1, including:

sighting a target from an observation point disposed on either one of both a land-base platform and a sea-borne platform.

9. The method according to claim 1, including:

supporting the PTAS on a stabilized platform.

10. The method according to claim 1, wherein:

measured data and associated information are available for output in digital format, and

displayed data and associated information are retrievable from the display.

11. The method according to claim 1, for rapidly finding accurate north direction, including:

obtaining at least a coarse north direction reading for input into the computer module,

running a north-finding procedure (NFP) computer program on the computer module for determining an observation zone sector, dividing the observation zone into sub-sectors and defining reference targets,

using an active range measuring device to actively measure range from the observation point to at least two reference targets,

feeding the at least two actively measured ranges into the computer module, and

running the NFP computer program for calculating deviation in azimuth data to the at least two reference targets by respectively associating range as calculated by the PTAS and range as actively measured for deriving a common azimuth deviation factor providing a correction factor for indicating the accurate north.

12. The method according to claim 11, including:

selecting randomly either one of both, one reference target in at least one sub-sector, and one reference target in each one of at least two non-adjacent sub-sectors.

13. The method according to claim 11, wherein running the NFP computer program includes:

dividing the observation zone automatically into sub-sectors, and

defining a selected reference target as a locus for which each small azimuth deviation of the sighting vector encounters a large change in range.

14. The method according to claim 11, including:

running the NFP computer program for calculating whether adjustment of the observation point location reduces the value of the common deviation factor, and

adjusting the observation point location when the accordingly calculated adjustment reduces the value of the common deviation factor.

15. The method according to claim 1, for rapidly finding accurate north direction, including:

obtaining at least a coarse north direction reading for input into the computer module,

running a north-finding procedure (NFP) computer program on the computer module for determining an observation zone, dividing the observation zone in sub-sectors and defining reference targets,

using an active range measuring device to actively measure range from the observation point to at least one reference target,

feeding the at least one actively measured range into the computer module, and

running the NFP computer program for calculating deviation in azimuth data to the at least one reference target by associating range to the reference target as calculated by the PTAS, and range as actively measured, for deriving an azimuth deviation factor providing a correction factor for indicating the accurate north.

16. The method according to claim 1, for passive super-rapid finding of accurate north direction, including:

defining a specific sighted target on the terrain surrounding the observation point and taking a coarse azimuth data reading thereto,

measuring location of the observation point, and both azimuth and elevation angle data to the specific sighted target, and feeding measured data as input data into the computer module,

running the PTAS computer program for calculating with input data and displaying results on the DTM surface as a coarsely calculated target,

finding the sighted singular target on the display, and reading specific sighted target data as accurate azimuth from the DTM surface, and

adjusting the coarsely calculated target azimuth with the accurate azimuth, which is fed to the computer module, for deriving an azimuth deviation factor providing a correction factor for indicating the accurate north.

17. A passive target data acquisition system (PTAS) positioned and operative at an observation point for passively sighting a target along a LOS vector, including:

passive sighting means comprising a navigation device for measuring location data of the observation point, and azimuth and elevation angle measuring devices for measuring azimuth and elevation angle data to the target,

a computer module operatively coupled to a DTM module, to the sighting means, and to a display, the computer module receiving measured location of the observation point and angular data of the target for presentation on display of a corresponding DTM surface derived from the DTM module, the PTAS comprising;

an envelope radially surrounding the LOS vector length which originates at the observation point, and an envelope mantle distanced away from the LOS vector proportionally to errors of measurement,

a PTAS computer program running on the computer module for calculating intersection points of the vector and of the envelope with the DTM surface, and

presenting the intersection points with associated information on the display, whereby target data is acquired passively to avoid emission of radiations.

18. The PTAS according to claim 17, wherein:

at least one target error-area is shown on the display in association with the target.

19. The PTAS according to claim 17, wherein associated information processed by the computer module, includes:

a way-point for the observation point and for the target, and

a range indicating the distance from the observation point to the target and to the at least one target error-area, and

associated information output in digital format configured for transmission, and for presentation on the display.

20. The PTAS according to claim 19, including:

a dead-zone detection capability provided by the PTAS computer program, for deriving the distance separating between target error-areas, when more than at least one target error-area is detected, and

dead-zone and error-area associated information output in digital format configured for transmission, and for presentation of dead-zone and error-area associated information on the display.

21. The PTAS according to claim 17, including:

a system configuration implemented as an aggregation of readily available modules integrated with added complementary modules and appropriate computer programs.

22. The PTAS according to claim 17, including:

a platform for operably supporting the PTAS, the platform being selected from the group of static and mobile platforms consisting of platforms based on land, in the air, at sea, and in space, and

the selected platform being implemented as either one of both a stabilized and a non-stabilized platform.

23. The PTAS according to claim 17, operating in association with a north finding procedure (NFP) computer program, having a coarse north direction reading obtained for input into the computer module, including:

a north-finding procedure (NFP) computer program running on the computer module for determining an observation zone sector, which is divided into sub-sectors with reference targets being defined therein,

an active range measuring device being used for actively measure range from the observation point to at least two reference targets,

at least two actively measured ranges being fed into the computer module, and

the NFP computer program being run for calculating deviation in azimuth data to the at least two reference targets by respectively associating range as calculated by the PTAS and range as actively measured for deriving a common azimuth deviation factor providing a correction factor for indicating the accurate north.

24. The PTAS according to claim 17, used for rapid north finding, including:

a specific sighted target chosen on the terrain, toward which a coarse azimuth angle reading is taken together with the observation point location and the elevation angle as measured with the sighting means, for input into the PTAS computer program and calculation of a resulting coarsely calculated target,

the PTAS computer module being run for display of the DTM surface showing the coarsely calculated target and surrounding terrain containing the specific sighted target, and

the specific sighted target is detected on the surface of the DTM on display, from which DTM azimuth data to the specific sighted target is retrieved as a true azimuth for input into the PTAS computer program, for correction therewith of the azimuth of the coarsely calculated target.

25. The PTAS according to claim 17, used for rapid north finding, including:

operating the PTAS for obtaining observation point location and pointing sighting means in the direction of a specific sighted target for display of a DTM surface,

identifying the selected target on the display and retrieving therefrom an accurate azimuth to the selected target, and

feeding the accurate azimuth into the PTAS computer program.