Method and apparatus for high-accuracy position location using search mode ranging techniques

• US 6,876,326 B2
• Filed: 04/23/2001
• Issued: 04/05/2005
• Est. Priority Date: 04/23/2001
• Status: Expired due to Fees

• Current Assignee: Exelis Incorporated (L3Harris Technologies, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Martorana, Marc J.
• Primary Examiner(s): Gregory, Bernarr E.
• Assistant Examiner(s): MULL, FRED H
• Application Number:
  US09/839,598
• Publication Number:
  US 20020155845A1
• Time in Patent Office: 1,443 Days
• Field of Search: 342 47- 49, 342/126, 342/363, 342/387, 342457-458, 340/7.5, 340/825.49
• US Class Current: 342/463
• CPC Class Codes: G01S 1/022 Means for monitoring or calibrating
• CPC Class Codes: G01S 2205/002 for traffic control, mobile tracking, guidance, surveillance or anti-collision
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A high accuracy search and tracking system that uses a round-trip messaging scheme in which the time of arrive (TOA) of ranging signals is accurately determined to yield the range estimates between a target communications device and one or more search communications devices. Successive ranging estimates are used by a search device to home in upon the target device. The physical location pinpoint communications system can be used alone, or in combination with other location estimation systems that can be used initially, or throughout the search and tracking process to pinpoint the physical location of the target device. The search radio(s) transmits ranging signals to the target radio which responds by transmitting reply ranging signals. Upon reception of the reply ranging signal, the search radio determines the range to the reference radio from the signal propagation time. Errors in TOA estimates can be minimized using advanced processing techniques, if required.

Claims

1. A method of pinpointing the physical position of a target communication device, comprising:

(a) determining a position of the target communication device with sufficient accuracy to direct a search communication device to within a vicinity of the target communication device;

(b) repeatedly measuring the range between the target communication device and the mobile search communication device once the search communication device is within the vicinity by repeatedly exchanging an outbound ranging signal and a reply ranging signal between the target communication device and the search communication device and determining a round-trip signal propagation time of the outbound ranging signal and the reply ranging signal; and

(c) directing movement of the search communication device toward the target communication device in response to the repeatedly measured range, thereby pinpointing the position of the target communication device by reducing the range between the search and target communication devices, wherein synchronization of system clocks of the target communication device and the mobile search communication device is not necessary.

2. The method of claim 1, wherein (a) includes determining the position of the target communication device from measurements of ranges between the target communication device and reference communication devices whose positions are known.

3. The method of claim 1, wherein (a) includes determining the position of the target communication device based upon a position entered manually via a user interface.

4. The method of claim 1, wherein the target communication device initiates a search for itself by broadcasting a search mode request.

5. The method of claim 1, wherein a central control device initiates a search for the target communication device by broadcasting a search mode request to potential search devices.

6. The method of claim 5, wherein communication devices not within the vicinity of the target communication device retransmit search mode requests broadcasted by the central control device, thereby extending the broadcast range of the central control device.

7. The method of claim 1, wherein the search communication device initiates a search for the target communication device by transmitting a search mode request to the target communication device.

8. A search communication device for pinpointing the physical position of a target communication device in a vicinity of the search communication device, comprising:

a transmitter configured to transmit an outbound ranging signal to the target communication device;

a receiver configured to receive a reply ranging signal from the reference communication device in response to the outbound ranging signal; and

a processor configured to determine the range to the target communication device from a round-trip signal propagation time of the reply ranging signal and the outbound ranging signal,

wherein said search communication device is configurable to operate in a search mode in which said search communication device repeatedly determines the range to the target communication device to enable an operator to direct movement of the search communication device toward the target communication device, thereby pinpointing the position of the target communication device by reducing the range between the search and target communication devices, and wherein synchronization of system clocks of the target communication device and the mobile search communication device is not necessary.

9. The search communication device of claim 8, wherein said search communication device is initially directed to a vicinity of the target communication device by an estimate of the position of the target communication device determined measurements of ranges between the target communication device and reference communication devices whose positions are known.

10. The search communication device of claim 8, wherein said search communication device is initially directed to a vicinity of the target communication device based on a position of the target communication device entered manually via a user interface.

11. The search communication device of claim 8, wherein the search mode is initiated by a broadcast search mode request transmitted by the target communication device.

12. The search communication device of claim 8, wherein the search mode is initiated by a broadcast search mode request transmitted by a central control device.

13. The search communication device of claim 12, wherein said search communication device retransmits search mode requests broadcasted by the central control device when said search communication device is not within the vicinity of the target communication device, thereby extending the broadcast range of the central control device.

14. The search communication device of claim 8, wherein said search communication device initiates a search for the target communication device by transmitting a search mode request to the target communication device.

15. The search communication device of claim 8, wherein said search communication device is a handheld device.

16. The search communication device of claim 8, wherein said search communication device is configured to be carried on a human body.

17. The search communication device of claim 8, wherein said search communication device is configured to operate in search mode onboard a moving vehicle.

18. The search communication device of claim 8, wherein said search communication device is capable of exchanging ranging signals with a target communication device located indoors.

19. A search communication device for pinpointing the physical position of a target communication device in a vicinity of the search communication device, comprising:

means for transmitting an outbound ranging signal to the target communication device;

means for receiving a reply ranging signal from the reference communication device in response to the outbound ranging signal; and

means for determining the range to the target communication device from a round-trip signal propagation time of the reply ranging signal and the outbound ranging signal, wherein said search communication device is configurable to operate in a search mode in which said search communication device repeatedly determines the range to the target communication device to enable an operator to direct movement of the search communication device toward the target communication device, thereby pinpointing the position of the target communication device by reducing the range between the search and target communication devices, wherein synchronization of system clocks of the target communication device and the mobile search communication device is not necessary.

20. The search communication device of claim 19, wherein said search communication device is initially directed to a vicinity of the target communication device by an estimate of the position of the target communication device determined measurements of ranges between the target communication device and reference communication devices whose positions are known.

21. The search communication device of claim 19, wherein said search communication device is initially directed to a vicinity of the target communication device based on a position of the target communication device entered manually via a user interface.

22. The search communication device of claim 19, wherein the search mode is initiated by a broadcast search mode request transmitted by the target communication device.

23. The search communication device of claim 19, wherein the search mode is initiated by a broadcast search mode request transmitted by a central control device.

24. The search communication device of claim 23, wherein said search communication device retransmits search mode requests broadcasted by the central control device when said search communication device is not within the vicinity of the target communication device, thereby extending the broadcast range of the central control device.

25. The search communication device of claim 19, wherein said search communication device initiates a search for the target communication device by transmitting a search mode request to the target communication device.

26. The search communication device of claim 19, wherein said search communication device is a handheld device.

27. The search communication device of claim 19, wherein said search communication device is configured to be carried on a human body.

28. The search communication device of claim 19, wherein said search communication device is configured to operate in search mode onboard a moving vehicle.

29. The search communication device of claim 19, wherein said search communication device is capable of exchanging ranging signals with a target communication device located indoors.

30. A system for pinpointing the physical position of a target communication device, comprising:

a search communication device configured to transmit an outbound ranging signal and receive a reply ranging signal;

a target mobile communication device configured to receive the outbound ranging signal and transmit the reply ranging signal to said search communication device, said search communication device determining the range to the target communication device from a round-trip signal propagation time of the reply ranging signal and the outbound ranging signal,

wherein said search and target communication devices are configurable to operate in a search mode in which said search communication device repeatedly determines the range to said target communication device to enable an operator to direct movement of said search communication device toward said target communication device, thereby pinpointing the position of said target communication device by reducing the range between said search and target communication devices, and wherein synchronization of system clocks of the target communication device and the mobile search communication device is not necessary.

31. The system of claim 30, wherein said search communication device is initially directed to a vicinity of the target communication device by an estimate of the position of the target communication device determined measurements of ranges between the target communication device and reference communication devices whose positions are known.

32. The system of claim 30, wherein said search communication device is initially directed to a vicinity of the target communication device based on a position of the target communication device entered manually via a user interface.

33. The system of claim 30, wherein the search mode is initiated by a broadcast search mode request transmitted by the target communication device.

34. The system of claim 30, wherein the search mode is initiated by a broadcast search mode request transmitted by a central control device.

35. The system of claim 34, wherein said search communication device retransmits search mode requests broadcasted by the central control device when said search communication device is not within the vicinity of the target communication device, thereby extending the broadcast range of the central control device.

36. The system of claim 30, wherein said search communication device initiates a search for the target communication device by transmitting a search mode request to the target communication device.

37. The system of claim 30, wherein said target communication device is a handheld device.

38. The system of claim 30, wherein said target communication device is configured to be carried on a human body.

39. The system of claim 30, wherein said target communication device is incorporated into clothing worn on the body.

40. The system of claim 30, wherein said target communication device is a mobile telephone.

41. The system of claim 30, wherein said search and target communication devices operate in the search mode onboard moving vehicles.

42. The system of claim 30, wherein said search and target communication devices are capable of exchanging ranging signals while indoors.