Method and system for localizing a target in an interrogation-response system

• US 6,933,879 B2
• Filed: 04/03/2003
• Issued: 08/23/2005
• Est. Priority Date: 04/05/2002
• Status: Expired due to Term

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Roze, Thierry, Trin, Jean-Marc
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/405,933
• Publication Number:
  US 20030222810A1
• Time in Patent Office: 873 Days
• Field of Search: 342119-127, 342450-465, 342/27, 342/28, 342 33- 40, 342 42- 51, 342104-107, 342/109, 342/115, 342/118, 342/128, 342133-135, 342/139, 342/146, 342/147, 342/149, 342150-154, 342/175, 342/195
• US Class Current: 342/45
• CPC Class Codes: G01S 13/78 discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe G01S13/75, G01S13/79 take precedence
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

In a method and system to determine the position of a target by means of an IFF type antenna, the antenna having a given direction of aim, the method comprises a step for combining the distance D from the target to the carrier, the altitude A of the target, the altitude A_pf of the carrier equipped with the IFF antenna and the angular error value of the target and the direction of aim of the antenna beam to localize the target with precision. Application to IFF interrogations in mode C.

Claims

1. A method of determining the position of a target using an antenna having a given direction of aim, wherein the method comprises;

combining at least three parameters that represent a position of the target, a position of a carrier of the antenna and an antenna beam-aiming direction to localize the target.

wherein the three parameters used are a distance D from the target to the carrier, an altitude A of the target and an altitude A_pf of the carrier equipped with the IFF antenna and the angular error value of the target.

2. The method according to claim 1, comprising the following steps:

determining a circle C₁ resulting from an intersection between an iso-distance sphere on which the target is situated and a plane substantially parallel to the vertical plane of the carrier equipped with the antenna;

determining a circle C₂ that comes from the intersection between an iso-altitude plane of the target and an iso-distance sphere; and

achieving the intersection of the two circles C₁ and C₂ to obtain the coordinates of the target.

3. The method according to claim 2, wherein the coordinates of the target are given by the following relationships:

$\hspace{1em}<br><br>\{\begin{array}{cc}z=D<br><br>\text{\hspace{1em}<br><br>}<br><br>\sin <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{\alpha <br><br>}<br><br>\text{\hspace{1em}<br><br>}+P\right)<br><br>\text{\hspace{1em}<br><br>}& \text{\hspace{1em}<br><br>}<br><br>\left(2\right)\\ y=A-A_{\mathrm{pf}}<br><br>\text{\hspace{1em}<br><br>}& \text{\hspace{1em}<br><br>}<br><br>\left(4\right)\\ x=\pm <br><br>\sqrt{D^2<br><br>\left(1-{\sin }^2<br><br>\left(\mathrm{\alpha <br><br>}+P\right)\right)-y_a^2}& \text{\hspace{1em}<br><br>}<br><br>\left(6\right)\end{array}$

4. The method according to claim 3, wherein the x coordinates are specified as follows:

$\hspace{1em}<br><br>\{\begin{array}{c}\mathrm{Si}-{90}^{\mathrm{°<br><br>}}<<br><br>\left(P+\mathrm{\alpha <br><br>}\right)<<br><br>+{90}^{\mathrm{°<br><br>}}\Rightarrow <br><br>x=\sqrt{D^2<br><br>\left(1-{\sin }^2<br><br>\left(\mathrm{\alpha <br><br>}+P\right)\right)-y_a}\\ \mathrm{Si}<br><br>\{\begin{array}{c}\left(P+\mathrm{\alpha <br><br>}\right)><br><br>+{90}^{\mathrm{°<br><br>}}\\ \left(P+\mathrm{\alpha <br><br>}\right)<<br><br>-{90}^{\mathrm{°<br><br>}}\end{array}\Rightarrow <br><br>x=-\sqrt{D^2<br><br>\left(1-{\sin }^2<br><br>\left(\mathrm{\alpha <br><br>}+P\right)\right)-y_a^2}<br><br>\text{\hspace{1em}<br><br>}\end{array}$

5. The method according to claim 4, wherein a mode of interrogation from the carrier to the target is an IFF mode C.

6. The method according to claim 3, wherein a mode of interrogation from the carrier to the target is an IFF mode C.

7. The method according to claim 2, wherein a mode of interrogation from the carrier to the target is an IFF mode C.

8. The method according to claim 2, wherein a mode of interrogation from the carrier to the target is an IFF mode C.

9. The method according to claim 1, wherein a mode of interrogation from the carrier to the target is an IFF mode C.

10. The method according to claim 1, comprising the following steps:

determining a circle C₁ resulting from an intersection between an iso-distance sphere on which the target is situated and a plane substantially parallel to the vertical plane of the carrier equipped with the antenna;

determining a circle C₂ that comes from the intersection between an iso-altitude plane of the target and an iso-distance sphere; and

achieving the intersection of the two circles C₁ and C₂ to obtain the coordinates of the target.

11. The method according to claim 1, wherein a mode of interrogation from the carrier to the target is an IFF mode C.

12. The system for the localization of a target by a carrier by means of a carrier equipped with an antenna wherein the system comprises:

a primary radar; and

an IFF system adapted to combine at least three parameters that represent a position of the target, a position of the carrier and an antenna beam-aiming direction to localize the target.

13. The system according to claim 12, wherein the three parameters used are a distance D from the target to the carrier, an altitude A of the target and an altitude A_pf of the carrier equipped with the IFF antenna and the angular error value of the target.

14. The system according to claim 12, wherein one parameter is a distance D from the target to the carrier.

15. The system according to claim 12, wherein one parameter is a position of the carrier.

16. The system according to claim 12, wherein one parameter is an antenna beam-aiming direction to localize the target.

17. The system according to claim 12, wherein the antenna has one of a given direction of aim and a secondary antenna.