Electronic transponder tuning circuitry

• US 5,491,484 A
• Filed: 12/22/1994
• Issued: 02/13/1996
• Est. Priority Date: 12/15/1992
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Schuermann, Josef H.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/362,368
• Time in Patent Office: 418 Days
• Field of Search: 342/51, 342/42, 342/44, 342/50
• US Class Current: 342/51
• CPC Class Codes: G01S 13/753 using frequency selective elements, e.g. resonator
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 13/825 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 7/4008 of transmitters
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: G06K 19/07777 the antenna being of the inductive type

Abstract

A method is disclosed herein for tuning a responder unit (12). The method comprises the stops of storing energy in a responder unit energy accumulator (136) in a contactless fashion by RF energy transmitted from the interrogator unit (10) to the responder unit (12), and exciting within the responder unit (12) an RF carrier wave. The method further comprises the stops of transmitting the RF carrier wave in a first response from the responder unit (12) to the interrogator unit (10) and measuring within the interrogator unit (10) the received signal strength of the RF carrier wave of the first response. In further accordance with the invention tuning data may be transmitted to the responder unit (12) by sending at least one RF programming sequence from the interrogator unit (10) to the responder unit (12). The responder unit (12) upon receiving the RF programming sequence from the interrogator unit (10) would preferably modify an internally stored frequency setting within a memory (244) of the responder unit (12) in response to the first set of data. Other devices, systems and methods are also disclosed.

Claims

1. An interrogator that transmits at least one RF interrogation pulse followed by at least one RF programming sequence containing tuning data to a responder, which is operable to transmit an RF response upon receipt of said at least one RF interrogation pulse, said interrogator comprising:

a) a detection circuit for detecting the strength of a carrier wave generated by said responder, and

b) a control circuit for analyzing the detected strength of said carrier wave and for determining if a new set of tuning data for another RF programming sequence needs to be computed.

2. The interrogator of claim 1 wherein said detection circuit comprises a pick-up coil that is loosely coupled to said resonant circuit of said responder unit for detecting the signal strength of said RF carrier wave.

3. The interrogator of claim 1 and further comprising an antenna operable to receive said RF response from said responder.

4. The interrogator of claim 3 wherein said detection circuit measures the signal strength of said RF response received at said antenna.

5. The interrogator of claim 4 and further comprising a demodulator for receiving said RF response from said antenna and demodulating data therefrom.

6. The interrogator of claim 5 wherein said demodulator and said detection circuit are integrated.

7. The interrogator of claim 6 wherein said integrated demodulator and detection circuit provides a radio signal strength indicator signal.

8. The interrogator of claim 7 wherein said radio signal strength indicator signal is an analog signal indicating the signal strength of said RF response received at said antenna.

9. The interrogator of claim 7 and further comprising an analog-to-digital converter electrically interposed between said detection circuit and said control circuit, said analog-to-digital converter being operable to create a digital signal representing the amplitude of said analog signal whereby said control circuit may directly determine whether a new set of tuning data for another RF programming sequence should be computed.

10. The interrogator of claim 1 and further comprising a memory for storing information representing the detected strength of said carrier wave.

11. The interrogator of claim 10 wherein said control circuit is operable to compare the detected signal strength of a first wireless response, as represented by information stored in said memory, to the detected signal strength of a second wireless response.

12. An interrogator that transmits at least one RF interrogation pulse followed by at least one RF programming sequence containing tuning data to a responder, which is operable to transmit an RF response upon receipt of said at least one RF interrogation pulse, said interrogator comprising:

a) an antenna operable to receive said RF response from said responder;

b) a detection circuit for detecting the strength at said antenna of a carrier wave generated by said responder and for providing an analog signal to said control circuit, said analog signal indicating the signal strength of said RF response received at said antenna; and

c) a control circuit for analyzing the detected strength of said carrier wave and for determining if a new set of tuning data for another RF programming sequence needs to be computed.

13. The interrogator of claim 12 and further comprising a demodulator for receiving said RF response from said antenna and demodulating data therefrom.

14. The interrogator of claim 13 wherein said demodulator and said detection circuit are integrated.

15. The interrogator of claim 12 and further comprising an analog-to-digital converter electrically interposed between said detection circuit and said control circuit, said analog-to-digital converter being operable to create a digital signal representing the amplitude of said analog signal whereby said control circuit may directly determine whether a new set of tuning data for another RF programming sequence should be computed.

16. An interrogator that transmits at least one RF interrogation pulse followed by at least one RF programming sequence containing tuning data to a responder, which is operable to transmit an RF response upon receipt of said at least one RF interrogation pulse, said interrogator comprising:

a) an antenna operable to receive said RF response from said responder;

b) a detection circuit for detecting the strength at said antenna of a carrier wave generated by said responder and for providing an analog signal to said control circuit, said analog signal indicating the signal strength of said RF response received at said antenna;

c) a demodulator for receiving said RF response from said antenna and demodulating data therefrom;

d) a control circuit for analyzing the detected strength of said carrier wave and for determining if a new set of tuning data for another RF programming sequence needs to be computed; and

e) an analog-to-digital converter electrically interposed between said detection circuit and said control circuit, said analog-to-digital converter being operable to create a digital signal representing the amplitude of said analog signal whereby said control circuit may directly determine whether a new set of tuning data for another RF programming sequence should be computed based upon said digital signal.

17. The interrogator of claim 16 wherein said demodulator and said detection circuit are integrated.