System and method for locating an object using global positioning system receiver

• US 6,657,586 B2
• Filed: 05/02/2002
• Issued: 12/02/2003
• Est. Priority Date: 05/03/2001
• Status: Expired due to Term

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Wherenet Corporation (Zebra Technologies Corporation)
• Inventors: Turner, Thomas E.
• Primary Examiner(s): Phan, Dao
• Application Number:
  US10/137,746
• Publication Number:
  US 20030001775A1
• Time in Patent Office: 579 Days
• Field of Search: 342/357.01, 342/357.03, 342/357.06, 342/357.07, 701/213, 701/215, 455/456.1, 455/456.3, 455/457
• US Class Current: 342/357.48
• CPC Class Codes: G01S 2205/002 for traffic control, mobile tracking, guidance, surveillance or anti-collision
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/0284 Relative positioning
• 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

Abstract

A system and method for locating an object uses a plurality of tag signal readers that receive wireless tag signals from a tag transmitter coupled with an object to be located. The tag signals include data indicating the identity of the object to which the tag transmitter is coupled. Each tag signal reader includes a global positioning system receiver associated therewith for determining the location of a tag signal reader. A wireless transmitter transmits a wireless data signal incorporating the wireless tag signal and location of the tag signal reader to a location processor, which receives the wireless data signals and determines which tag signals are first-to-arrive signals and conducts differentiation of the first-to-arrive signals to locate a tag transmitter and object coupled therewith.

Claims

1. A system for locating an object comprising:

a plurality of tag signal readers for receiving wireless tag signals from a tag transmitter coupled with an object to be located, said tag signals having data indicating the identity of the object to which the tag transmitter is coupled, each tag signal reader further comprising a global positioning system receiver associated therewith for determining the location of a tag signal reader, and a wireless transmitter for transmitting a wireless data signal incorporating the wireless tag signal and location of the tag signal reader; and

a location processor for receiving the wireless data signal from the tag signal readers for determining which tag signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals relative to the location of the tag signal readers as determined by the global positioning system receivers to locate a tag transmitter and object coupled therewith.

2. A system according to claim 1, wherein said wireless tag signals comprise pseudo random spread spectrum radio frequency signals.

3. A system according to claim 1, wherein said location processor comprises a matched filter correlator.

4. A system according to claim 3, wherein said matched filter correlator further comprises matched filter banks having parallel correlators that correlate a received communications signal with time offset versions of a reference spreading code.

5. A system according to claim 1, wherein said location processor further comprises a plurality of processors for distributing processing capability.

6. A system according to claim 1, wherein three tag signal readers are used for determining the location of the object to be located.

7. A system according to claim 1, wherein each tag signal reader comprises a plurality of mutually diverse antennas for detecting wireless tag signals at each tag signal reader.

8. A system according to claim 1, wherein each tag signal reader further comprises a mobile device having a battery for self-powering the tag signal reader.

9. A system according to claim 8, wherein said wireless data signal transmitted from a tag signal reader further comprises telemetry information regarding power levels of a battery within the tag signal reader.

10. A system according to claim 1, wherein said wireless data signal transmitted from a wireless transmitter comprises a packet signal.

11. A system according to claim 10, wherein said packet signal comprises a header containing global positioning system information related to the location of a tag signal reader.

12. A system according to claim 1, wherein said global positioning system receiver at each tag signal reader comprises a differential global positioning system receiver.

13. A method for locating an object comprising the steps of:

generating a wireless tag signal from a tag transmitter coupled with an object to be located to a plurality of tag signal readers, said tag signals having data indicating the identity of the object to which the tag transmitter is coupled, each tag signal reader further comprising a global positioning system receiver associated therewith for determining the location of a tag signal reader;

transmitting a wireless data signal incorporating the wireless tag signal and location of the tag signal reader;

receiving the wireless data signal from the tag signal readers within a location processor; and

determining within the location processor which tag signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals relative to the location of the tag signal readers as determined by the global positioning system receivers to locate a tag transmitter and object coupled therewith.

14. A method according to claim 13, and further comprising the step of transmitting the wireless tag signals as pseudo random spread spectrum radio frequency signals.

15. A method according to claim 13, and further comprising the step of processing the wireless data signals within the location processor using a matched filter correlator.

16. A method according to claim 15, and further comprising the step of processing with matched filter banks having parallel correlators that correlate a received communications signal with time offset versions of a reference spreading code.

17. A method according to claim 13, and further comprising the step of distributing processing capability within the location processor by using a plurality of processors.

18. A method according to claim 13, and further comprising the step of using three tag signal readers for determining the location of an object.

19. A method according to claim 13, and further comprising the step of receiving tag signals with mutually diverse antennas.

20. A method according to claim 13, and further comprising the step of self-powering a tag signal reader using a battery.

21. A method according to claim 20, and further comprising the step of transmitting telemetry information regarding power levels of a battery within a tag signal reader.

22. A method according to claim 13, and further comprising the step of transmitting the wireless data signal as a packet signal.

23. A method according to claim 22, and further comprising the step of transmitting a header within the packet signal that contains global positioning system information related to the location of a tag signal reader.