Dual mode transmitter-receiver and decoder for RF transponder tags

• US 7,741,956 B1
• Filed: 07/28/2004
• Issued: 06/22/2010
• Est. Priority Date: 11/29/1996
• Status: Expired due to Fees

• Current Assignee: X-Cyte Inc.
• Original Assignee: X-Cyte Inc.
• Inventors: Nysen, Paul A.
• Primary Examiner(s): Brown; Vernal U
• Application Number:
  US10/901,743
• Time in Patent Office: 2,155 Days
• Field of Search: 340/10.41, 340/10.4, 340/10.1, 340/825.69, 340/825.72, 340/825.58, 340/10.32, 340/10.3, 340/10.2, 340/10.31, 340/5.64, 340/10.42, 340/10.43, 340/10.51, 340/10.33, 340/10.34, 340/572.5, 340/572.2, 340/572.4
• US Class Current: 340/10.41
• CPC Class Codes: G01S 13/755 using delay lines, e.g. acoustic delay lines
• CPC Class Codes: G06K 19/0675 the resonating marks being of the surface acoustic wave [SAW] kind SAW devices per se H03H9/64
• 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: H03H 9/642 SAW transducers details for remote interrogation systems, e.g. surface acoustic wave transducers details for ID-tags remote interrogation systems per se G06K7/10009, G01S13/74

Abstract

An enhanced backscatter RF-ID tag reader system and multiprotocol RF tag reader system is provided. In a multiprotocol mode, the system emits a non-stationary interrogation signal, and decodes a phase modulated backscatter signal by detecting a stronger phase component from quadrature phase representations or determining phase transition edges in a phase of a received signal. The RF tag reader system predicts or follows the phase of the backscatter signal, thereby avoiding interference from nulls in the received signal waveform due to the non-stationary interrogation signal, relative movement or environmental effects. An acoustic RF-ID tag detection system detects the reradiated signal corresponding to respective transformation of a signal in the tag. Detection of either type of RF-ID tags therefore is possible, and the absence of any tag or absence of any valid tag also determined.

Claims

1. A method of reading information from different types of tags in an RFID system using an RFID reader, comprising:

radiating, from an antenna of a transmitter of said RFID reader, a propagating radio frequency (RF) signal to a first tag of a first type and to a second tag of a second type, said first and second tags of said first and second types configured to employ respective first and second encoding schemes for generating first and second encoded RF signals;

receiving, by said RFID reader, the first and second encoded RF signals propagated from said first and second tags of said first and second types, said first and second encoded RF signals containing information associated with the first tag and information associated with the second tag;

demodulating the first and second encoded radio RF signals to generate demodulated first and second demodulated signals; and

decoding the demodulated first and second demodulated signals to extract said information associated with the first tag and said information associated with the second tag.

2. The method of claim 1 wherein said first and second tags of said first and second types employ first and second different modulation schemes.

3. The method of claim 2 wherein the first modulation scheme comprises FSK.

4. The method of claim 1 wherein one of the first and second tags of said first and second types is an active tag.

5. The method of claim 1 wherein one of the first and second tags of said first and second types is a passive tag.

6. The method of claim 5 wherein the passive tag comprises a semiconductor-based memory tag.

7. The method of claim 1 wherein the RF signal radiated from the antenna of said transmitter is modulated by a first interrogation signal associated with said first tag of said first type.

8. The method of claim 7 wherein the RF signal radiated from the antenna of said transmitter is modulated by a second interrogation signal associated with said second tag of said second type.

34. The method of claim 1 wherein the RFID reader and the first tag are separated by a distance that is greater than a wavelength of the RF signal transmitted from said transmitter to the first tag.

35. The method of claim 1 wherein the transmitter consists of a single transmitter.

36. The method of claim 1 wherein the first tag is a backscatter modulation type of tag.

37. The method of claim 1 wherein said RF signal has a frequency that is greater than ten (10) MHz.

9. An RFID system, comprising:

a reader configured to radiate a radio frequency (RF) signal to RFID tags employing different encoding schemes; and

a plurality of tags configured to receive the RF signal, said plurality of tags including a first tag configured to modify the RF signal according to a first encoding scheme to generate a first encoded RF signal, and a second tag configured to modify the RF signal according to a second encoding scheme different than the first encoding scheme to generate a second encoded RF signal,

wherein said reader is configured to receive said first and second encoded RF signals from said first and second tags by way of propagation of the first and second encoded RF signals from the first and second tags to said reader and not by way of near-field electromagnetic coupling with said reader.

10. The RFID system of claim 9 wherein the reader further comprises a decoder configured to extract information associated with the first and second tags encoded in the first and second encoded RF signals.

11. The RFID system of claim 9 wherein the reader comprises:

a first decoder configured to extract information associated with the first tag encoded by the first encoding scheme; and

a second decoder configured to extract information associated with the second tag encoded by the second encoding scheme.

12. The RFID system of claim 9 wherein the first tag is an active tag.

13. The RFID system of claim 9 wherein the first tag is a passive tag.

14. The RFID system of claim 9 wherein the first tag is a semiconductor-based memory tag.

15. The RFID system of claim 9 wherein said first and second tags are further configured to employ different modulation schemes.

16. The RFID system of claim 9 wherein the RF carrier is modulated by a first interrogation signal, which said first tag is responsive to.

17. The RFID system of claim 16 wherein the RF carrier is modulated by a second interrogation signal, which said second tag is responsive to.

38. The RFID system of claim 9 wherein said reader includes a singular transmitter configured to transmit said RF signal to said plurality of tags.

39. The RFID system of claim 38 wherein a distance between the first tag and said reader is greater than a wavelength of the RF signal transmitted by said singular transmitter.

40. The RFID system of claim 39 wherein said distance is multiple wavelengths of the RF signal.

41. The RFID system of claim 9 wherein the RF signal transmitted by said transmitter has a frequency that is greater than ten (10) MHz.

18. An RFID reader, comprising:

a transmitter configured to radiate a radio frequency (RF) signal to a first group of tags employing a first encoding scheme and a second group of tags employing a second encoding scheme different from said first encoding scheme;

a receiver configured to receive a first encoded RF signal reflected from a tag of said first group of tags and a second encoded RF signal reflected from a tag of said second group of tags, said first encoded RF signal containing information associated with the tag of said first group of tags and said second encoded RF signal containing information associated with the tag of said second group of tags; and

a decoder operable to extract the information associated with the tag of said first group of tags and extract the information associated with the tag of said second group of tags.

19. The RFID reader of claim 18 wherein said decoder comprises:

a first decoder operable to extract the information associated with the tag of said first group of tags; and

a separate, second decoder operable to extract the information associated with the tag of said second group of tags.

20. The RFID reader of claim 18 wherein said tag of said first group of tags comprises an active tag.

21. The RFID reader of claim 18 wherein said tag of said first group of tags comprises a passive tag.

22. The RFID reader of claim 18 wherein the tag of said first group of tags comprises a semiconductor-based memory tag.

23. The RFID reader of claim 18 wherein the first and second groups of tags are configured to employ different modulation schemes.

24. The RFID reader of claim 18 wherein the RF signal transmitted from said transmitter is modulated by a first interrogation signal, which only said first group of tags is responsive to.

25. The RFID reader of claim 24 wherein the RF signal transmitted from said transmitter is modulated by a second interrogation signal, which only said second group of tags is responsive to.

42. The RFID reader of claim 18 wherein said transmitter consists of a single transmitter.

43. The RFID reader of claim 18 wherein a distance between the tag of the first group of tags and said reader is greater than a wavelength of the RF signal transmitted by said transmitter.

44. The RFID reader of claim 43 wherein said distance is multiples of the wavelength of the RF signal transmitted by said transmitter.

45. The RFID reader of claim 18 wherein the tag of the first group of tags is a backscatter modulation type of tag.

46. The RFID reader of claim 18 wherein the RF signal transmitted by said transmitter has a frequency that is greater than ten (10) MHz.

47. The RFID reader of claim 18 wherein said first and second encoded RF signals are generated by modulating the RF signal with both said information associated with the tag of said first group of tags and said information associated with said second group of tags.

26. An RFID reader, comprising:

a transmitter configured to radiate a radio frequency (RF) signal to first and second tags;

a receiver configured to receive a first encoded RF signal reflected from the first tag and a second encoded RF signal reflected from the second tag, said first encoded RF signal encoded by an encoding scheme different than an encoding scheme used to encode said second encoded RF signal, and said receiver including a demodulator configured to demodulate said first and second encoded RF signals; and

a decoder configured to decode demodulated first and second encoded RF signals from said demodulator,

wherein said first tag is a passive tag comprising an integrated circuit chip, and wherein said receiver is configured to receive said first encoded RF signal reflected from said passive tag when said passive tag is separated from said receiver by a distance greater than a wavelength of the RF signal radiated from said transmitter.

27. The RFID reader of claim 26 wherein said first tag is configured to employ a first modulation scheme, said second tag is configured to employ a second modulation scheme different from said first modulation scheme, and said demodulator is configured to demodulate encoded RF signals from said first tag that are modulated in accordance with said first modulation scheme and to demodulate encoded RF signals from said second tag that are modulated in accordance with said second modulation scheme.

48. The RFID reader of claim 26 wherein said transmitter consists of a single transmitter.

49. The RFID reader of claim 26 wherein said first tag is in the far-field, relative to the receiver, and the receiver is configured to receive said first encoded RF signal by way of propagation from said first tag to the receiver and not by way of inductive coupling between said first tag and the receiver.

50. The RFID reader of claim 26 wherein said distance is multiple wavelengths of the RF signal transmitted by the transmitter.

51. The RFID reader of claim 26 wherein said first tag is a backscatter modulation type of tag.

52. The RFID reader of claim 26 wherein the RF signal transmitted from said transmitter has a frequency that is greater than ten (10) MHz.

28. A method of reading tag information, comprising:

radiating, from a transmitter of an RFID reader, a radio frequency (RF) signal to a first plurality of tags employing a first modulation scheme and to a second plurality of tags employing a second modulation scheme different from said first modulation scheme; and

receiving, by a receiver of said RFID reader, first modulated RF signals reflected from said first plurality of tags and second modulated RF signals reflected from said second plurality of tags,

wherein said first plurality of tags comprises a plurality of backscatter modulation tags configured to generate said first modulated RF signal by way of backscatter modulation.

29. The method of claim 28 wherein said first and/or second modulation schemes employ frequency shift keying (FSK).

53. The method of claim 28 wherein said transmitter of said RFID reader consists of a single transmitter.

54. The method of claim 28 wherein a distance between said tags of first plurality of tags and said receiver is greater than a wavelength of the RF signal transmitted by said transmitter.

55. The method of claim 54 wherein said distance is multiple wavelengths of the RF signal transmitted by said transmitter.

56. The method of claim 28 wherein a phase shift of the RF signal resulting from the RF signal traveling from the transmitter to a tag of the first plurality of tags and back to the receiver is greater than forty-five (45) degrees.

57. The method of claim 28 wherein the RF signal transmitted from the transmitter has a frequency that is greater than ten (10) MHz.

30. An RFID reader, comprising:

a transmitter configured to transmit RF signals to RFID tags of first and second types; and

a receiver including a demodulator circuit configured to demodulate first and second RF modulated signals reflected from said RFID tags of the first and second types,

wherein the receiver is configured to receive the first and second RF modulated signals from the RFID tags of the first and second types by way of propagation and not by way of inductive coupling to an inductive field of said receiver.

31. The RFID reader of claim 30 wherein said RFID tag of the first type employs an encoding scheme that is different than an encoding scheme employed by said RFID tag of the second type.

32. The RFID reader of claim 30 wherein said RFID tag of the first type employs a modulation scheme that is different than a modulation scheme employed by said RFID tag of the second type.

33. The RFID reader of claim 30 wherein said transmitter consists of a single transmitter.