Systems and methods for TDOA/FDOA location

• US 7,508,344 B2
• Filed: 11/29/2005
• Issued: 03/24/2009
• Est. Priority Date: 11/29/2005
• Status: Expired due to Fees

• Current Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Inventors: Stroud, Ken A.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Nguyen; Nga X
• Application Number:
  US11/288,975
• Publication Number:
  US 20070120738A1
• Time in Patent Office: 1,211 Days
• Field of Search: 342/387, 342/444, 342/446, 342/449
• US Class Current: 342/387
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

Systems and methods that may be implemented to determine the location of an emitter of electromagnetic radiation, such as an RF signal emitter having an unknown location, using at least two electromagnetic radiation sensor antennas that are co-located on a single sensing platform in combination with at least one other electromagnetic radiation sensor antenna located on another sensing platform.

Claims

1. A method of processing electromagnetic radiation, comprising:

receiving said electromagnetic radiation at a first position, said first position being located on a first sensing platform;

receiving said electromagnetic radiation at a second position and at a third position, said second and third positions being co-located in spaced relationship on a second sensing platform;

measuring first time difference of arrival (TDOA) information for said electromagnetic radiation between said first position and said second position;

measuring frequency difference of arrival (FDOA) information for said electromagnetic radiation between said first position and at least one of said second and third positions;

at least one of;

measuring second TDOA information for said electromagnetic radiation between said second position and said third position, or

measuring third TDOA information for said electromagnetic radiation between said first position and said third position, or

a combination thereof; and

determining a location of an emitter of said electromagnetic radiation based at least in part on an intersection of data determined from said first measured TDOA information with data determined, from said measured FDOA information and with at least one of data determined from said second TDOA information, data determined from said third TDOA information, or a combination thereof;

wherein said location of said emitter of said electromagnetic radiation is determined using data determined from TDOA and FDOA information measured while said first sensing platform and said second sensing platform are moving differently relative to each other and are moving relative to said emitter of said electromagnetic radiation;

wherein said location of said emitter of said electromagnetic radiation is determined without receiving said electromagnetic radiation at a position on a third sensing platform and without repositioning said first and second sensing platforms to new locations for measurement of additional TDOA or FDOA information.

2. The method of claim 1, further comprising:

defining a first hyperboloid using said first measured TDOA information;

defining a surface using said measured FDOA information;

defining a second hyperboloid using said second measured TDOA information, or defining a third hyperboloid using said third measured TDOA information, or a combination thereof; and

determining a location of said earth-based emitter of said electromagnetic radiation based on an intersection point of said surface of the earth with said first hyperboloid, said surface, and at least one of said second or third hyperboloids.

3. The method of claim 1, wherein said first sensing platform is a first aircraft;

wherein said second sensing platform is a second aircraft;

wherein said first aircraft is moving at a first heading and first velocity relative to the emitter of the electromagnetic radiation;

wherein said second aircraft is moving at a second heading and second velocity relative to the emitter of the electromagnetic radiation; and

wherein said first heading is different from said second heading and said first velocity is different from said second velocity such that said first aircraft and said second aircraft are moving differently relative to each other while said TDOA and FDOA information is measured.

4. The method of claim 1, wherein said emitter of said electromagnetic radiation is earth-based;

wherein said first sensing platform is a first aircraft; and

wherein said second sensing platform is a second aircraft.

5. A method for locating an emitter of a radio frequency (RF) signal, said method comprising:

receiving said RF signal at a first sensor antenna, said first sensor antenna being located on a first sensing platform;

receiving said RF signal at a second sensor antenna and at a third sensor antenna, said second and third sensor antennas being co-located in spaced relationship on a second sensing platform;

measuring first time difference of arrival (TDOA) information for said RF signal between said first position and said second antenna sensors;

measuring frequency difference of arrival (FDOA) information for said RF signal between said first antenna sensor and at least one of said second and third antenna sensors;

measuring second TDOA information for said RF signal between said second antenna sensor and said third antenna sensor, or measuring third TDOA information for said RF signal between said first antenna sensor and said third antenna sensor, or a combination thereof; and

determining a location of said RF signal emitter based at least in part on an intersection of data determined from said first measured TDOA information with data determined from said measured FDOA information and with at least one of data determined from said second TDOA information, data determined from said third TDOA information, or a combination thereof;

wherein said location of said RF signal emitter of said electromagnetic radiation is determined using data determined from TDOA and FDOA information measured while said first sensing platform and said second sensing platform are moving differently relative to each other and are moving relative to said RF signal emitter of said electromagnetic radiation; and

wherein said location of said RF signal emitter is determined without receiving said RF signal at a sensor antenna on a third sensing platform, and without repositioning said first and second sensing platforms to new locations for measurement of additional TDOA or FDOA information.

6. The method of claim 5, wherein said first sensing platform is moving at a first velocity and first heading relative to said RF signal emitter;

wherein said second sensing platform is moving at a second velocity and second heading relative to said RF signal emitter; and

wherein said first velocity is different from said second velocity and said first heading is different from said second heading such that said first sensing platform and said second sensing platform are moving differently relative to each other while said TDOA and FDOA information is measured.

7. The method of claim 5, wherein said RE signal emitter is earth-based and wherein said method further comprises:

defining a first hyperboloid using said first measured TDOA information;

defining a surface using said measured FDOA information;

defining a second hyperboloid using said second measured TDOA information, or defining a third hyperboloid using said third measured TDOA information, or a combination thereof; and

determining a geo-location of said RF signal emitter based on an intersection point of said surface of the earth with said first hyperboloid, said surface, and at least one of said second or third hyperboloids.

8. The method of claim 7, wherein said first and second sensing platforms are each aircraft.

9. The method of claim 7, wherein said first and second sensing platforms are each satellites in earth orbit.

10. The method of claim 7, wherein said RF signal emitter comprises a cell phone.

11. The method of claim 10, wherein said first and second sensing platforms are each satellites in earth orbit.

12. An emitter location system, comprising:

a first sensing platform configured to receive electromagnetic radiation at a first position on said first sensing platform, said first sensing platform comprising signal processing circuitry configured to process electromagnetic radiation received at said first position on said first sensing platform on a time and frequency basis;

a second sensing platform configured to receive electromagnetic radiation at a second position on said second sensing platform and at a third position on said second sensing platform, said second and third positions being co-located in spaced relationship on said second sensing platform, and said second sensing platform comprising signal processing circuitry configured to process electromagnetic radiation received at said second and third positions on said second sensing platform on a time and frequency basis;

time difference of arrival (TDOA) processing circuitry configured to communicate with said signal processing circuitry of said first sensing platform and said signal processing circuitry of said second sensing platform; and

frequency difference of arrival (FDOA) processing circuitry configured to communicate with said signal processing circuitry of said first sensing platform and said signal processing circuitry of said second sensing platform, said TDOA and FDOA processing circuitry being configured to;

measure first TDOA information for said electromagnetic radiation between said first position and said second position,

measure FDOA information for said electromagnetic radiation between said first position and at least one of said second or third positions,

measure second TDOA information for said electromagnetic radiation between said second position and said third position, or measure third TDOA information for said electromagnetic radiation between said first position and said third position, or a combination thereof, and

determine a location of an emitter of said electromagnetic radiation based at least in part on an intersection of data determined from said first measured TDOA information with data determined from said measured FDOA information and with data determined from at least one of said second TDOA information, said third TDOA information, or a combination thereof;

wherein said TDOA and FDOA processing circuitry are further configured to determine said location of said emitter of said electromagnetic radiation using data determined from TDOA and FDOA information measured while said first sensing platform and said second sensing platform are moving differently relative to each other and are moving relative to an emitter of said electromagnetic radiation;

wherein said TDOA and FDOA processing circuitry are further configured to determine said location of said emitter of said electromagnetic radiation without receiving said electromagnetic radiation at a sensor on a third sensing platform, and without repositioning said first and second sensing platforms to new locations for measurement of additional TDOA or FDOA information.

13. The system of claim 12, wherein said TDOA and FDOA processing circuitry is configured to:

define a first hyperboloid using said first measured TDOA information;

define a surface using said measured FDOA information;

define a second hyperboloid using said second measured TDOA information, or define a third hyperboloid using said third measured TDOA information, or a combination thereof; and

determine a geo-location of an earth-based emitter of said electromagnetic radiation based on an intersection point of the surface of the earth with said first hyperboloid, said surface, and at least one of said second hyperboloid, said third hyperboloid, or a combination thereof.

14. The system of claim 12, wherein said first and second sensing platforms are each aircraft;

wherein said electromagnetic radiation comprises a radio frequency (RF) signal;

wherein said first sensing platform comprises a first sensor antenna at said first position, said first sensor antenna being coupled to said signal processing circuitry of said first sensing platform; and

wherein said second sensing platform comprises a second sensor antenna at said second position and a third sensor antenna at said third position, said second sensor antenna and said third sensor antenna being coupled to said signal processing circuitry of said second sensing platform.

15. The system of claim 12, wherein said first and second sensing platforms are each satellites.