Transmitter location for ultra-wideband, transmitted-reference CDMA communication system

• US 7,499,711 B2
• Filed: 06/30/2003
• Issued: 03/03/2009
• Est. Priority Date: 10/09/2001
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Tomlinson, Harold Woodruff Jr., Hershey, John Erik, Van Stralen, Nick Andrew, Hoctor, Ralph Thomas
• Primary Examiner(s): ZEWDU, MELESS NMN
• Application Number:
  US10/609,891
• Publication Number:
  US 20040002347A1
• Time in Patent Office: 2,073 Days
• Field of Search: 4554561-4566, 455/16, 455/67.11, 455/433, 455/440, 455524-526, 455/550.1, 455/556.2, 455/561, 455 411- 413, 455100-105, 455/115.1, 455/132, 455224-225, 4554041-4042, 455410-411, 455418-420, 455/422.1, 455457-458, 455/3.01, 455/66.1, 455/67.16, 455/91, 455 95- 96, 4552261-2264, 455/424, 369/13.2, 369/30, 340/426.19, 340/426.2, 340/426.21, 340/426.22, 340989-994, 3405391-53919, 340/539.32, 340/572.1, 340/572.7, 3405731-5734, 34053921-53923, 340540-541, 340/686.6, 340/825.49, 340/7.25, 330305-306, 381320-321, 701300-302, 701/207, 701/209, 701213-216, 701/225, 342125-134, 348/116
• US Class Current: 455/456.1
• 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: H04B 1/7163 using impulse radio

Abstract

A system and method involve determining the location of objects within an area of interest using wireless signals. The system includes at least three base stations communicating with a central processor and a plurality of mobile devices. Further, at least one fixed beacon transmitter of known location may be provided. The mobile devices transmit a wireless signal to the base stations, which then determine a location of the mobile devices based on time difference of arrival information between the mobile devices measured at all the base stations.

Claims

1. A method for determining a location of at least one transmitting object within an area of interest, comprising:

transmitting wireless signals from a plurality of transmitting objects to at least three receivers;

transmitting signals from a plurality of beacon transmitters to the at least three receivers, each of said plurality of beacon transmitters being at a known location and having an independent local clock;

calculating, at each of the at least three receivers, a plurality of time differences of arrival data based on respective signals from said plurality of beacon transmitters and the wireless signals transmitted from the plurality of transmitting objects; and

determining the location of the at least one of the plurality of transmitting objects within said area of interest based on said plurality of time differences of arrival data from said at least three receivers.

2. The method of claim 1, wherein said wireless signals comprise RF signals.

3. The method of claim 2, wherein said RF signals comprise UWB signals.

4. The method of claim 3, wherein said UWB signals comprise TR-UWB signals.

5. The method of claim 3, wherein said UWB signals comprise TR/DH UWB signals;

and wherein the step of transmitting TR/DH UWB signals comprises generating pairs of pulses separated by a time interval D and encoding by relative polarity of pulses of said pairs; and

wherein the step of calculating time difference of arrival data comprises delaying received signals by the time interval D.

6. The method of claim 5, wherein the step of transmitting further comprises generating the pairs of pulses at a pulse repetition rate which is variable in order to shape a spectrum of transmission.

7. The method of claim 5, wherein the TR/DH UWB signals are transmitted from a plurality of objects, each TR/DH UWB signal having a different time interval D between pulses of said pairs.

8. The method of claim 7, wherein the step of transmitting the UWB signals further includes transmitting medical information of a patient with the UWB signals.

9. The method of claim 3, wherein the step of transmitting the UWB signals is performed by a transmitter carried by a patient, and wherein said area of interest is a medical facility.

10. The method of claim 3, wherein the step of transmitting the UWB signals is performed by a transmitter attached to medical equipment, and wherein said area of interest is a medical facility.

11. The method of claim 1, wherein the step of determining the location of the at least one of the plurality of transmitting objects comprises using a least squares algorithm.

12. A system for determining a location of an object within an area of interest, comprising:

a mobile device carried by each of a plurality of objects, said mobile device including a transmitter for transmitting a wireless signal, the wireless signal comprising a TD/DH UWB (transmitted-reference, delayed hopped ultra-wide band) RF signal;

at least three base stations within said area of interest, each of said at least three base stations comprising a detector for detecting wireless signals transmitted from a plurality of said mobile devices, and further comprising a processor for deriving time difference of arrival information based on the detected wireless signals, the detector comprising a pulse-pair correlator; and

a controller for determining the location of at least one of the objects within said area of interest based on the time difference of arrival information calculated by each of the three base stations.

13. The system of claim 12, wherein said transmitter transmits said TR/DH UWB signals having a variable pulse repetition time.

14. The system of claim 12, wherein at least one of said objects is a patient and said area of interest is a medical facility.

15. The system of claim 12, wherein at least one of said objects is medical equipment and said area of interest is a medical facility.

16. The system of claim 12, wherein the transmitter of the mobile device transmits medical information of said patient with the RF signal.

17. A method for determining a location of a transmitting object within an area of interest, comprising:

receiving a plurality of wireless signals from a plurality of transmitting objects, the plurality of wireless signals received by at least three receivers, the signals comprising pair of pulses separated by a time interval D; and

determining the location of least one of the transmitting objects within said area of interest based on time difference of arrival information calculated at each of the at least three receivers, said calculation of the time difference of arrival information based on the plurality of wireless signals delayed by the time interval D.

19. The method of claim 17, wherein said wireless signals comprise TR/DH UWB RF signals.

20. The method of claim 17, wherein the step of determining the location of the at least one of the objects comprises using a least squares algorithm.

18. A system for determining a location of an object within an area of interest, comprising:

a mobile device carried by each of a plurality of objects, said mobile device including a transmitter for transmitting a wireless signal;

at least three base stations within said area of interest, each of said at least three base stations comprising a detector for detecting wireless signals transmitted from the plurality of said objects each carrying said mobile device, the detector comprising a pulse-pair correlator and each of said at least three base stations further comprising a processor for deriving time difference of arrival information based on the detected wireless signals; and

a controller for determining the location of at least one of the plurality of objects within said area of interest based on the time difference of arrival information calculated by each of the three base stations.

21. The system of claim 18, wherein said wireless signals comprise TR/DH UWB RF signals.

22. The system of claim 18, wherein said transmitter transmits said wireless signals having a variable pulse repetition time.