Dual mode transmitter-receiver and decoder for RF transponder tags

• US 6,531,957 B1
• Filed: 05/17/2002
• Issued: 03/11/2003
• 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): Horabik, Michael
• Assistant Examiner(s): Dalencourt, Yves
• Application Number:
  US10/150,848
• Time in Patent Office: 298 Days
• Field of Search: 340/10.1, 340/10.3, 340/10.4, 340/10.41, 342/42, 342/44, 342/51, 455/73, 455/106, 375/219
• US Class Current: 340/10.1
• 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. An interrogation apparatus for reading an identification from a remote transponder, comprising:

(a) a transceiver, producing a radio frequency interrogation signal which is radiated through an antenna toward the remote transponder, and receiving a backscatter response from the remote transponder, having an identification signal modulating said interrogation signal, said backscatter response being in accordance with one of a plurality of protocols;

(b) a homodyne detector for producing a demodulated representation of the identification signal from said received backscatter response and said interrogation signal;

(c) a plurality of signal processing channels coupled to said homodyne detector, each analyzing said demodulated representation of the identification to extract a series of digital data states therein according to a selected one of said protocols, each of said plurality of signal processing channels receiving said demodulated representation of the identification signal from a common homodyne detector and independently producing said series of data states;

(d) at least one analyzer coupled to said signal processing channels, employing digital logic circuitry having a plurality of logic gates to logically analyze said series of data states and determine the identification of the remote transponder; and

(e) a common output coupled to said at least one analyzer, communicating the identification of the remote transponder.

2. The apparatus according to claim 1, wherein said plurality of signal processing channels each process said demodulated representation of the identification differently.

3. The apparatus according to claim 2, further comprising digital logic circuitry which selects the identification produced by a single analyzer, which is communicated to said common output.

4. The apparatus according to claim 1, wherein an identification signal compatible with at least one analyzer comprises a frequency shift key modulated, biphase encoded serial data stream.

5. The apparatus according to claim 1, wherein the identification signal compatible with at least one analyzer is defined within the remote transponder by a set of semiconductor memory locations, which are sequentially read to produce a sequence of modulation states which are imposed on the backscatter response.

6. The apparatus according to claim 1, further comprising:

means disposed at the transponder and responsive to the interrogation signal for generating successive pluralities of signal cycles in a pattern individual to the object, the signal cycles in each plurality including signal cycles at both first and second frequencies in a pattern representative of a binary “

1”

or a binary “

0”

,

means disposed at the transponder for transmitting the successive pluralities of signal cycles at the first and second frequencies to the reader, and

at least one of said analyzers decoding the pattern of the frequencies of the signal cycles in each of the successive pluralities to identify the object.

7. The apparatus according to claim 1, further comprising:

means disposed at the transponder for generating successive pluralities of signals cycles in a pattern individual to the remote transponder, the signal cycles in each plurality including one signal cycle at a first frequency and two signal cycles at a second frequency constituting the second harmonic of the first frequency, the signal cycles at the second frequency preceding the signal cycle at the first frequency in each plurality representative of a binary “

1” and

the signal cycles at the first frequency preceding the signal cycle at the second frequency for each plurality representing a binary “

0”

, said successive pluralities of signals being modulated with said radio frequency signal to produce the backscatter response,

at least one of said analyzers being means for decoding the pattern of the frequencies of the signal cycles in each of the successive pluralities to identify the object.

8. The apparatus according to claim 7, wherein at least one of said analyzers comprises:

means for delaying the successive pluralities of the received signal cycles by a first delay time;

means for comparing the received signal cycles and the signal cycles delayed by the first delay time to obtain a demodulation of the information represented by the signal cycles in the successive pluralities;

means for delaying the successive pluralities of the received signal cycles by a second delay time different from the first delay time;

means for comparing the received signal cycles and the signal cycles delayed by the second delay time to generate phase-locked signals; and

means responsive to the phase-locked signals for generating clock signal cycles to facilitate the decoding of the information represented by the signal cycles in the successive pluralities.

9. The apparatus according to claim 1, further comprising a modulator to modulate the radio frequency interrogation signal, at least one of said analyzers being responsive to a signal from the remote transponder triggered by the modulation of the radio frequency signal.

10. The apparatus according to claim 1, wherein at least two different types of remote transponders are irradiated by the radio frequency interrogation signal, each producing a backscatter response having different characteristics, a first type of remote transponder producing an identification signal processed by a first of said analyzers and a second type of remote transponder producing an identification signal processed by a second of said analyzers, thereby permitting a mixed population of remote transponders to be identified by an apparatus having a single radio frequency signal processing circuit.

11. The apparatus according to claim 1, further comprising a variable frequency oscillator for generating said radio frequency signal.

12. The apparatus according to claim 11, wherein said variable frequency oscillator is a voltage controlled oscillator.

13. The apparatus according to claim 1, wherein the remote transponder is responsive to a radio frequency pulse to produce the backscatter response.

14. The apparatus according to claim 1, wherein said radio frequency signal is radiated toward an interrogation window, wherein said apparatus determines a type of remote transponder, if any, within said interrogation window.

15. The apparatus according to claim 1, further comprising a plurality of different types of remote transponders respectively employing different RF-ID techniques, to provide a single hybrid tag system.

16. The apparatus according to claim 1, wherein said remote transponder comprises an interactive tag which downloads information from said radio frequency interrogation signal, said radio frequency interrogation signal being modulated to provide a signal communicating information to the remote transponder.

17. The apparatus according to claim 1, wherein the backscatter response is monitored for an information transmission protocol.

18. The apparatus according to claim 1, wherein the backscatter response comprises, in a particular identifying pattern, pluralities of signal cycles at first an second frequencies in a first sequence to identify a binary “

0” and

in a second sequence, different from the first sequence, to identify a binary “

1” and

transmits the pluralities of signal cycles in the particular pattern of the first and second sequences;

at least one of said analyzers comprising;

first means for receiving the pluralities of signal cycles in the particular pattern of the first and second sequences;

second means for comparing the received pluralities of signal cycles and the received pluralities of signal cycles delayed by a first time period to detect the information coded by the received pluralities of signal cycles;

third means for comparing the received pluralities of signal cycles and the received pluralities of signal cycles delayed by a second time period different from the first time period to generate phase-locked signals;

fourth means for comparing the received pluralities of signal cycles and the received pluralities of signal cycles delayed by a third time period different from the first and second time periods to generate additional phase-locked signal cycles at times different from the phase-locked signals generated by the third means; and

fifth means responsive to the phase-locked locked signals generated by third and fourth means for synchronizing the detection of the information generated by the received pluralities of signals with the generation of the phase-locked signals and the additional phase-locked signals.

19. The apparatus according to claim 1, wherein the backscatter response comprises the radio frequency signal modulated in a pattern comprising pluralities of signal cycles at first and second frequencies in a first sequence to identify a binary “

0” and

in a second sequence, different from the first sequence, to identify a binary “

1”

, said binary “

0” and

“

1”

being used to encode the identification;

at least one of said analyzers comprising;

means for delaying the signal cycles for a first particular time period related to the first and second frequencies;

means for delaying the signal cycles for a second particular time period related to the first and second frequencies but different from the first particular time period;

means for delaying the signal cycles for a third particular time period related to the first and second frequencies but different from the first and second particular time periods;

means for comparing the received signal cycles and the signal cycles delayed by the first time period for generating phase-locked signals;

means for comparing the received signals and the signals delayed by the second time period for generating additional phase lock signals at the times not generated by the first comparing means;

means for comparing the received signal cycles and the signal cycles delayed by the third time period for generating demodulated signals; and

means responsive to the demodulated signals and the phase-locked signal cycles and the additional phase-locked signal cycles for recovering the identification.

20. The apparatus according to claim 1, wherein the identification signal is modulated onto the radio frequency signal in the backscatter response as a sequence of modulation states using frequency shift keying modulation.

21. An interrogation apparatus for reading an identification from a remote transponder within an interrogation zone irradiated by a radio frequency interrogation signal, the remote transponder modulating an identification signal on a radio frequency interrogation signal to product a backscatter response according to a predetermined protocol, comprising:

(a) a receiver, receiving a backscatter response from an antenna;

(b) a common detector, demodulating the backscatter response to produce a demodulated representation of the identification signal;

(c) a plurality of signal processing channels, each separately analyzing said demodulated representation of the identification signal from said common detector, according to a respectively different channel protocol, to extract a series of digital data states therein;

(d) an analyzer coupled to said plurality of signal processing channels, logically analyzing said series of data states to determine a type of remote transponder within the interrogation zone and an identification thereof; and

(e) an output, communicating the determined identification of the remote transponder.

22. The apparatus according to claim 21, wherein said analyzer comprises digital logic circuitry which selects the identification using data states produced by a single analyzer, which is communicated to said output.

23. The apparatus according to claim 21, wherein one of said signal processing channels is responsive to a frequency shift key modulated, biphase encoded serial data stream.

24. The apparatus according to claim 21, wherein one of said signal processing channels is responsive to a Manchester encoded, frequency shift key modulated data stream employing two key frequencies which are related as first and second harmonics.

25. The apparatus according to claim 21, wherein the identification signal is defined within the remote transponder by a set of semiconductor memory locations, which are sequentially read to produce a sequence of modulation states which are imposed on the backscatter response.

26. The apparatus according to claim 21, wherein the interrogation signal is modulated, at least one of said analyzers being selectively responsive to a signal from the remote transponder triggered by the modulation of the interrogation signal.

27. The apparatus according to claim 21, wherein at least two different types of remote transponders are irradiated by the interrogation signal, each producing a backscatter response having different characteristics, a first type of remote transponder producing an identification signal processed by a first of said analyzers and a second type of remote transponder producing an identification signal processed by a second of said analyzers, thereby permitting a mixed population of remote transponders to be identified by an apparatus having a single radio frequency signal processing circuit.

28. The apparatus according to claim 21, wherein the interrogation signal has an adjustable frequency.

29. The apparatus according to claim 21, wherein the remote transponder is responsive to an interrogation signal comprising a radio frequency pulse to produce the backscatter response.

30. The apparatus according to claim 21, wherein the remote transponder comprises an interactive tag which downloads information from said interrogation signal, said interrogation signal being selectively modulated to provide a signal communicating information to the remote transponder.

31. The apparatus according to claim 30, wherein a first channel selectively processes an identification signal from the remote transponder which downloads information from said interrogation signal and a second channel selectively processes an identification signal from the remote transponder which does not download information from said interrogation signal, said analyzer determining a valid identification based on an inferred type of remote transponder