Real-time emitter locating system and method

• US 7,242,351 B2
• Filed: 02/24/2004
• Issued: 07/10/2007
• Est. Priority Date: 02/24/2003
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Networkfab Corporation (Agilent Technologies, Inc.)
• Inventors: Karlsson, Lars, Soloviev, Dmitri
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Mull; Fred H.
• Application Number:
  US10/785,353
• Publication Number:
  US 20040164901A1
• Time in Patent Office: 1,232 Days
• Field of Search: 342/449, 342/450, 342/451, 342/457
• US Class Current: 342/449
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders

Abstract

A Real-time Emitter Locating (EL) System and Method is disclosed. The system provides a technique for taking in data sets (lines of bearing) from DF receivers and characterizing those signals with their respective probabilities of error. Then using a unique method, the preferred system applies a recursive processing technique to this continuous stream of data, displaying transmitter positions with significantly less uncertainty. Furthermore, the preferred system is able to perform these functions in real-time. The system is further capable of being fully automated to reduce the processing time and reduce the necessity of human intervention. Still further, in an alternative embodiment of the present invention the system can be remotely controlled over a communications network whereby collected locating data from a single DF set, or alternatively from more than one DF sets can be combined to arrive at estimated positions for a transmitter. In this way, a far more efficient EL System can be achieved in which the emitter'"'"'s position can be determined more quickly from a centralized command facility. This combination of data filtering and data collection techniques significantly reduces measurement uncertainties and enhances the accuracy of EL systems.

Claims

1. A direction-finding method comprising the steps of:

establishing a cross-over position point;

relocating a receiver to a new receiver spacial location;

said receiver at said new receiver position receiving a transmission from a transmitter at a transmitter position;

determining a real-time line of bearing from said receiver to said transmitter;

generating a connecting vector from said real-time line of bearing to said cross-over position point; and

identifying a real-time position of said transmitter along said connecting vector.

2. The method of claim 1, wherein said identifying comprises identifying a best guess transmitter position responsive to said real-time position of said transmitter.

3. The method of claim 2, further comprising the steps of:

again relocating said receiver to a new receiver spacial location;

said receiver at said new receiver position receiving a transmission from said transmitter at a transmitter position;

determining another said real-time line of bearing from said receiver to said transmitter;

generating a said connecting vector from said last real-time line of bearing to said best guess transmitter position; and

identifying said best guess position of said transmitter along said connecting vector.

4. The method of claim 3, wherein:

said determining step further comprises determining a quality factor for said real-time line of bearing; and

said identifying step further comprises assigning a probability factor to said real-time position of said transmitter responsive to said quality factor.

5. The method of claim 3, further comprising a repeating step to repeat said relocating, receiving, determining, generating and identifying steps until said probability factor exceeds a predetermined threshold value.

6. The method of claim 3, further comprising a repeating step to repeat said relocating, receiving, determining, generating and identifying steps until a user terminates said direction finding method.

7. The method of claim 3, further comprising a repeating step to repeat said relocating, receiving, determining, generating and identifying steps until said probability factor meets a user-defined threshold value.

8. A direction-finding method executed by a portable DF set comprising a receiver and a programmable computing system comprising a processors, an input device, an output device and a storage medium, the method comprising the steps of:

establishing a cross-over position point representing a position of a transmitter and outputting said point at said output device;

moving said DF set to a new DF set position;

receiving at said DF set in said new DF set position, a transmission from said transmitter;

determining, via said programmable computer, a real-time line of bearing from said DF set to said transmitter responsive to said transmission;

generating, via said programmable computer, a connecting vector from said real-time line of bearing to said cross-over position point; and

determining a real-time transmitter position along said connecting vector and outputting said position at said output device.

9. The method of claim 8, wherein said identifying comprises identifying a best guess transmitter position responsive to said real-time position of said transmitter.

10. The method of claim 9, further comprising the steps of:

again relocating said receiver to a new receiver spacial location;

said receiver at said new receiver position receiving a transmission from said transmitter at a transmitter position;

determining another said real-time line of bearing from said receiver to said transmitter;

generating a said connecting vector from said last real-time line of beating to said best guess transmitter position; and

identifying said best guess position of said transmitter along said connecting vector.

11. The method of claim 10, wherein:

said determining step further comprises determining a quality factor for said real-time line of bearing; and

said identifying step further comprises assigning a probability factor to said real-time position of said transmitter responsive to said quality factor.

12. The method of claim 10, further comprising a repeating step to repeat said relocating, receiving, determining, generating and identifying stops until said probability factor exceeds a predetermined threshold value.

13. The method of claim 10, further comprising a repeating step to repeat said relocating, receiving, determining, generating and identifying steps until a user terminates said direction finding method.

14. The method of claim 10, further comprising a repeating step to repeat said relocating, receiving, determining, generating and identifying steps until said probability factor meets a user-defined threshold value.

15. A real-time direction-finding system, comprising:

a transmitter transmitting wireless transmissions, said transmitter defining a spatial location;

a DF set comprising a movable receiver for receiving said transmissions; and

a computing device for determining said location of said transmitter responsive to transmissions received by said movable receiver and not responsive to other said receivers, wherein said computing device operatively;

generates a cross-over point, said cross-over point defined as the intersection of a pair of sequential real-time lines of bearing from said DF set each line of bearing corresponding to a wireless transmission from said transmitter received by said DF set;

receives a transmission signal responsive to a transmission received by said DF set after said DF set has been moved to a new spatial location;

determines areal-time line of bearing from said DF set to said transmitter responsive to said transmission signal;

generates a connecting vector from said real-time line of bearing; and

determines a real-time transmitter position along said connecting vector and outputting said position at an output device associated with said computing device.