Method for determining a direction to a signal-emitting object

• US 9,625,562 B2
• Filed: 07/03/2012
• Issued: 04/18/2017
• Est. Priority Date: 07/03/2012
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Holte, Sven
• Primary Examiner(s): Gregory, Bernarr
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US14/405,669
• Publication Number:
  US 20150168534A1
• Time in Patent Office: 1,750 Days
• CPC Class Codes: G01S 11/04 using angle measurements
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H01Q 1/287 integrated in a wing or a stabiliser
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence

Abstract

The present invention relates to a method for determining a direction to a signal-emitting object by means of a platform comprising at least two antennas separated by a known distance. The method comprises said steps of: receiving, with each of said at least two antennas, a signal from said signal-emitting object at first positions, determining a first phase relation of said signal between said at least two antennas, —receiving, with each of said at least two antennas, a signal from said signal-emitting object at at least second positions, determining at least a second phase relation of said signal between said at least two antennas, characterized by the steps of: determining change(s) in position(s) of at least one antenna of said at least two antennas, and determining a direction to a signal-emitting object based on said first phase relation, said at least second phase relation and said change(s) in position(s) of said at least one antenna. The invention further relates to a platform performing a determination of a direction to a signal-emitting object.

Claims

1. A computer-implemented method for determining a direction (44) to a signal-emitting object via a platform comprising at least two antennas separated by a known distance, said method comprising the steps of:

(a) receiving, with each of said at least two antennas (31, 32), one or more signals from said signal-emitting object at first positions (41a);

(b) automatically determining, via at least one processing unit, a first phase relation of said one or more signals between said at least two antennas (31, 32);

(c) receiving, with each of said at least two antennas (31, 32), one or more signals from said signal-emitting object at at least second positions (41b);

(d) automatically determining, via the at least one processing unit, at least a second phase relation of said one or more signals between said at least two antennas (31, 32);

(e) automatically detecting, via the at least one processing unit and a position determination unit, a change in orientation of said platform;

(f) automatically determining, via the at least one processing unit, one or more corresponding changes in one or more positions (43) of each of said at least two antennas (31, 32) of said at least two antennas (31, 32), said one or more corresponding changes in said one or more positions (43) of each of said at least two antennas (31, 32) is based on said detected change in orientation of said platform; and

(g) automatically, determining, via the at least one processing unit, a direction (44) to said signal-emitting object based on said first phase relation, said at least second phase relation, and said one or more changes in said one or more positions (43) of each of said at least two antennas (31, 32),

wherein;

said at least two antennas (31, 32) define a long base interferometer (LBI);

said at least two antennas (31, 32) are mounted on said platform (30);

said platform (30) is an airborne vehicle;

said change in orientation of said platform (30) is at least one of a roll or a turn of said airborne vehicle;

said at least one of a roll or a turn occurs in a direction perpendicular to a travelling movement of said airborne vehicle; and

said method further comprises the step of repeating said steps (a)-(g) at least until ambiguities have been resolved with a desired degree of accuracy.

2. Method according to claim 1, wherein the reception of the first and the at least second signal are taken into account only when a main lobe of the antenna radiation pattern from the signal-emitting object is facing said platform.

3. Method according to claim 1, wherein the determination of said direction (44) to said signal-emitting object is based on virtual antenna array aperture formed by said one or more changes in said one or more positions (43) of said at least one antenna (31).

4. Method according to claim 1, further comprising the step of determining a distance (46) to said signal-emitting object based on variations in determined directions to said signal-emitting object over a period of time.

5. Method according to claim 1, further comprising the step of determining a distance (46) to said signal-emitting object based on the direction to a land-based signal emitting object and on the height of an airborne platform.

6. Method according to claim 1, further comprising the step of determining a distance (46) to said signal-emitting object based on determined directions from at least two platforms with different geographical positions using a cross bearing technique.