Interrogator and interrogation system employing the same

• US 20050201450A1
• Filed: 03/03/2005
• Published: 09/15/2005
• Est. Priority Date: 03/03/2004
• Status: Active Grant

• Current Assignee: Lone Star SCM Systems, LP (f/k/a Medical I.P. Holdings, LP) (Incucomm Holdings Management, LLC)
• Original Assignee: Veroscan, Inc. (Tenet Healthcare Corporation)
• Inventors: McMurry, Eric, Volpi, John P., Scott, Logan
• Granted Patent: US 8,948,279 B2
• Time in Patent Office: Days
• US Class Current: 375/150
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications

Abstract

A control and processing system for use with an interrogator and an interrogation system employing the same. In one embodiment, the control and processing system includes a correlation subsystem having a correlator that correlates a reference code with a reply code from a radio frequency identification (RFID) tag and provides a correlation signal therefrom. The control and processing system also includes a decision subsystem that verifies a presence of the RFID tag as a function of the correlation signal.

Claims

1. A control and processing system, comprising:

a correlation subsystem configured to correlate a reference code with a reply code from a radio frequency identification (RFID) tag and provide a correlation signal therefrom; and

a decision subsystem configured to verify a presence of said RFID tag as a function of said correlation signal.

2. The control and processing system as recited in claim 1 wherein said correlation subsystem is configured to correlate in a time domain employing an exclusive OR function.

3. The control and processing system as recited in claim 1 wherein said correlation subsystem is configured to correlate employing a Fast Fourier Transform and a convolution theorem.

4. The control and processing system as recited in claim 1 wherein said correlation subsystem is configured to align said reply code with said reference code at a fraction of a data bit interval.

5. The control and processing system as recited in claim 1 wherein said correlation subsystem includes multiple correlators configured to correlate at least one of multiple timing and multiple phases of said reference code with at least one of multiple timing and multiple phases of said reply code, respectively.

6. The control and processing system as recited in claim 1 wherein said correlation subsystem includes multiple correlators configured to correlate said reference code with said reply code and another reference code with another reply code.

7. The control and processing system as recited in claim 1 wherein said correlation subsystem is configured to correlate portions of said reference code with portions of said reply code.

8. The control and processing system as recited in claim 1 wherein said correlation subsystem includes:

a correlator configured to correlate at least two bits of said reference code with at least two bits of said reply code to derive a correlation triangle,

a correlation threshold sense configured to compare said correlation triangle to a threshold criteria to derive a pulse to ascertain a peak of said correlation triangle, and

a summer configured to average a plurality of pulses from said correlation threshold sense to provide said correlation signal.

9. The control and processing system as recited in claim 1 wherein said decision subsystem includes a threshold detector configured to compare said correlation signal to a threshold.

10. The control and processing system as recited in claim 1 wherein said reference code is a synthetically derived reference code.

11. The control and processing system as recited in claim 1 wherein said reference code is configured to provided during an initialization stage of operation and said reply code is configured to be provided during a post-initialization stage of operation.

12. The control and processing system as recited in claim 1 wherein said reference code is configured to be provided from said RFID tag affixed to an RFID object.

13. The control and processing system as recited in claim 1 wherein said reference code is configured to be entered into memory of said control and processing system.

14. The control and processing system as recited in claim 1 wherein said correlation subsystem is configured to employ multiple amplitude bits of at least one of said reference code and said reply code.

15. The control and processing system as recited in claim 1 wherein said correlation subsystem is configured to employ at least one of said reference code and said reply code as a spreading code.

16. A method verifying a presence of a radio frequency identification (RFID) tag, comprising:

correlating a reference code with a reply code from an RFID tag and providing a correlation signal therefrom; and

verifying a presence of said RFID tag as a function of said correlation signal.

17. The method as recited in claim 16 further comprising aligning said reply code with said reference code at a fraction of a data bit interval.

18. The method as recited in claim 16 wherein said act of correlating includes:

correlating at least two bits of said reference code with at least two bits of said reply code to derive a correlation triangle,

comparing said correlation triangle to a threshold criteria to derive a pulse to ascertain a peak of said correlation triangle, and

averaging a plurality of pulses from said correlation threshold sense to provide said correlation signal.

19. The method as recited in claim 16 wherein said act of verifying includes comparing said correlation signal to a threshold.

20. The method as recited in claim 16 further comprising synthetically deriving said reference code.

21. An interrogator, comprising:

a radio frequency identification (RFID) sensing subsystem configured to provide a reply code associated with an RFID tag; and

a control and processing subsystem, including;

a correlation subsystem configured to correlate a reference code with said reply code and provide a correlation signal therefrom, and

a decision subsystem configured to verify a presence of said RFID tag as a function of said correlation signal.

22. The interrogator as recited in claim 21 wherein said correlation subsystem is configured to correlate in a time domain employing an exclusive OR function.

23. The interrogator as recited in claim 21 wherein said correlation subsystem is configured to correlate employing a Fast Fourier Transform and a convolution theorem.

24. The interrogator as recited in claim 21 wherein said correlation subsystem is configured to align said reply code with said reference code at a fraction of a data bit interval.

25. The interrogator as recited in claim 21 wherein said correlation subsystem includes multiple correlators configured to correlate at least one of multiple timing and multiple phases of said reference code with at least one of multiple timing and multiple phases of said reply code, respectively.

26. The interrogator as recited in claim 21 wherein said correlation subsystem includes multiple correlators configured to correlate said reference code with said reply code and another reference code with another reply code.

27. The interrogator as recited in claim 21 wherein said correlation subsystem is configured to correlate portions of said reference code with portions of said reply code.

28. The interrogator as recited in claim 21 wherein said correlation subsystem includes:

a correlator configured to correlate at least two bits of said reference code with at least two bits of said reply code to derive a correlation triangle,

a correlation threshold sense configured to compare said correlation triangle to a threshold criteria to derive a pulse to ascertain a peak of said correlation triangle, and

a summer configured to average a plurality of pulses from said correlation threshold sense to provide said correlation signal.

29. The interrogator as recited in claim 21 wherein said decision subsystem includes a threshold detector configured to compare said correlation signal to a threshold.

30. The interrogator as recited in claim 21 wherein said reference code is a synthetically derived reference code.

31. The interrogator as recited in claim 21 wherein said reference code is configured to provided to said interrogator during an initialization stage of operation and said RFID sensing subsystem is configured to provide said reply code during a post-initialization stage of operation.

32. The interrogator as recited in claim 21 wherein said RFID sensing subsystem is configured to provide said reference code from said RFID tag affixed to an RFID object.

33. The interrogator as recited in claim 21 wherein said correlation subsystem is configured to employ multiple amplitude bits of at least one of said reference code and said reply code.

34. The interrogator as recited in claim 21 wherein said correlation subsystem is configured to employ at least one of said reference code and said reply code as a spreading code.

35. The interrogator as recited in claim 21 further comprising a metal sensing subsystem configured to provide a signal having a metal signature representing a presence of a metal object, said control and processing subsystem configured to discern a presence of said metal object from said signal.

36. A method of operating an interrogator, comprising:

providing a reference code associated with an RFID tag of an RFID object;

entering said reference code into memory;

subsequently sensing a reply code from said RFID tag;

correlating said reference code with said reply code and providing a correlation signal therefrom; and

verifying a presence of said RFID tag as a function of said correlation signal.

37. The method as recited in claim 36 wherein said act of correlating includes:

correlating at least two bits of said reference code with at least two bits of said reply code to derive a correlation triangle,

comparing said correlation triangle to a threshold criteria to derive a pulse to ascertain a peak of said correlation triangle, and

averaging a plurality of pulses from said correlation threshold sense to provide said correlation signal.

38. The method as recited in claim 36 wherein said act of verifying includes comparing said correlation signal to a threshold.

39. The method as recited in claim 36 wherein said act of providing said reference code includes synthetically deriving said reference code.

40. The method as recited in claim 36 further comprising providing a signal having a metal signature representing a presence of a metal object and discerning a presence thereof.

41. An interrogation system, comprising:

a computer system;

a transceiver that transmits and receives signals for said computer system; and

an interrogator, including;

a radio frequency identification (RFID) sensing subsystem that provides a reply code associated with an RFID tag of an RFID object,

a control and processing subsystem, including;

a correlation subsystem that correlates a reference code with said reply code and provides a correlation signal therefrom, and

a decision subsystem that verifies a presence of said RFID tag as a function of said correlation signal, and

a communications subsystem that communicates with said transceiver.

42. The interrogation system as recited in claim 41 wherein said correlation subsystem correlates in a time domain employing an exclusive OR function.

43. The interrogation system as recited in claim 41 wherein said correlation subsystem correlates employing a Fast Fourier Transform and a convolution theorem.

44. The interrogation system as recited in claim 41 wherein said correlation subsystem aligns said reply code with said reference code at a fraction of a data bit interval.

45. The interrogation system as recited in claim 41 wherein said correlation subsystem includes multiple correlators that correlate at least one of multiple timing and multiple phases of said reference code with at least one of multiple timing and multiple phases of said reply code, respectively.

46. The interrogation system as recited in claim 41 wherein said correlation subsystem includes multiple correlators that correlate said reference code with said reply code and another reference code with another reply code.

47. The interrogation system as recited in claim 41 wherein said correlation subsystem correlates portions of said reference code with portions of said reply code.

48. The interrogation system as recited in claim 41 wherein said correlation subsystem includes:

a correlator that correlates at least two bits of said reference code with at least two bits of said reply code to derive a correlation triangle,

a correlation threshold sense that compares said correlation triangle to a threshold criteria to derive a pulse to ascertain a peak of said correlation triangle, and

a summer that averages a plurality of pulses from said correlation threshold sense to provide said correlation signal.

49. The interrogation system as recited in claim 41 wherein said decision subsystem includes a threshold detector that compares said correlation signal to a threshold.

50. The interrogation system as recited in claim 41 wherein said reference code is a synthetically derived reference code.

51. The interrogation system as recited in claim 41 wherein said interrogator receives said reference code during an initialization stage of operation and said RFID sensing subsystem provides said reply code during a post-initialization stage of operation.

52. The interrogation system as recited in claim 41 wherein said RFID sensing subsystem provides said reference code from said RFID tag.

53. The interrogation system as recited in claim 41 wherein said correlation subsystem employs multiple amplitude bits of at least one of said reference code and said reply code.

54. The interrogation system as recited in claim 41 wherein said correlation subsystem employs at least one of said reference code and said reply code as a spreading code.

55. The interrogation system as recited in claim 41 wherein said interrogator further includes a metal sensing subsystem that provides a signal having a metal signature representing a presence of a metal object, said control and processing subsystem discerning a presence of said metal object from said signal.

56. The interrogation system as recited in claim 41 wherein said interrogator further includes memory and a user interface.

57. The interrogation system as recited in claim 41 wherein said RFID sensing subsystem employs a RFID position marker to indicate a location of a feature.

58. The interrogation system as recited in claim 41 wherein said RFID sensing subsystem employs a RFID sensing antenna interface and a RFID sensing antenna.

59. The interrogation system as recited in claim 41 wherein said communications subsystem communicates with said transceiver over an Internet.

60. The interrogation system as recited in claim 41 further comprising a database coupled to said computer system.