System and method for initiating communications between a controller and a selected subset of multiple transponders in a common RF field

• US 5,434,572 A
• Filed: 06/07/1994
• Issued: 07/18/1995
• Est. Priority Date: 06/07/1994
• Status: Expired due to Term

• Current Assignee: Poulsen Transmitter LLC (Intellectual Ventures LLC)
• Original Assignee: Ramtron International Corporation (Infineon Technologies AG)
• Inventors: Smith, Gregory M.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/255,088
• Time in Patent Office: 406 Days
• Field of Search: 342/51, 342/44, 342/42
• US Class Current: 342/44
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 13/82 wherein continuous-type signals are transmitted
• CPC Class Codes: G01S 13/825 with exchange of information between interrogator and responder
• 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 7/10039 interrogator driven, i.e. synchronous

Abstract

A system and method for initiating communication between a controller and a selected one or other subset of multiple transponders in a common RF field in which each transponder has a unique, (or commonly unique) preprogrammed ID number. The controller transmits a series of commands/questions to the transponders and they either respond, or do not respond, to the controller based on their ID number, with the non-responding transponders entering a reset state. The transponders respond to the controller in such a way that, if multiple transponders respond, the controller can recognize that at least one transponder has responded and, for individual responses, the controller is not required to determine how many transponders have responded. Through use of the communications system and method disclosed, a sequence of controller commands and transponder responses single out a selected individual transponder or group of transponders based upon its particular ID number.

Claims

1. A method for initiating communications between a controller and a selected subset of a plurality of transponders wherein each of said transponders includes an n-bit digital address, the method comprising the steps of:

initially transmitting a first digital signal from said controller to said plurality of transponders representative of a possible first bit of said n-bit digital address of said plurality of transponders;

responsively transmitting a signal from a first subset of said plurality of transponders having said possible first bit as said first bit of its n-bit digital address to said controller, said non-responsively transmitting transponders alternatively entering a reset state;

nextly transmitting a next digital signal from said controller to a responding plurality of transponders representative of a possible next bit of said n-bit digital address of said first subset of said plurality of transponders;

responsively transmitting a signal from a second subset of said first subset of transponders having said possible next bit as said next bit of its n-bit digital address to said controller, said non-responsively transmitting transponders alternatively entering a reset state; and

alternatively transmitting additional next digital signals from said controller to said plurality of transponders representative of possible additional next bits of said n-bit digital address of said responsively transmitting transponders until said digital signals transmitted from said controller to said plurality of transponders representative of said possible first, next and additional next bits of said n-bit address correspond witch said first, next and additional next bits of said n-bit address of said selected subset of said plurality of transponders.

2. The method of claim 1 further comprising the step of:

lastly transmitting a last digital signal from said controller to said plurality of transponders when said one of said plurality of transponders has responsively transmitted a signal to said controller indicative of a predetermined n-bit address of said selected one of said plurality of transponders.

3. The method of claim 1 further comprising the step of:

secondarily transmitting a second digital signal from said controller to said plurality of transponders representative of an alternative possible first bit of said n-bit digital address of said plurality of transponders if no transponders responsively transmit a signal in response to said first digital signal.

4. The method of claim 1 wherein said steps of initially, nextly and alternatively transmitting are carried out by means of an FSK modulated RF signal.

5. The method of claim 1 wherein said steps of responsively transmitting are carried out by means of a PSK modulated RF signal.

6. The method of claim 1 wherein said n-bit address comprises three digital bits.

7. The method of claim 1 wherein said first, next and additional next signals comprise two digital bits.

8. The method of claim 2 wherein said last digital signal comprises two digital bits.

9. A method for initiating communications with a selected subset of a plurality of transponders in a common RF field of a controller, wherein each of said plurality of transponders has an n-bit address, said method comprising the steps of:

transmitting a first signal to said plurality of transponders from said controller to establish a given logic level of a first bit of said n-bit addresses wherein said transponders having said given logic level as said first bit of their n-bit address respond to said controller and said non-responding transponders enter a reset state and alternatively transmitting a next signal to said plurality of transponders from said controller to establish an opposite logic level of said first bit of said n-bit addresses if none of said transponders respond to said first signal wherein said transponders having said opposite logic level as said first bit of their n-bit address respond to said controller and said non-responding transponders enter a reset state; and

selectively transmitting logic level inquiry signals to said plurality of transponders from said controller to establish a logic level of each remaining bit of said n-bit addresses wherein said transponders having logic levels of said remaining bits of their n-bit address corresponding to said logic level inquiry signals respond to said controller and said non-responding transponders enter a reset state.

10. The method of claim 9 further comprising the step of:

lastly transmitting a transponder found signal to said plurality of transponders in said common RF field in response to a remaining one of said transponders having an n-bit address corresponding to said first and logic level inquiry signals.

11. The method of claim 9 wherein said steps of transmitting and selectively transmitting are carried out by means of an FSK modulated RF signal.

12. The method of claim 9 wherein said transponders respond to said steps of transmitting and selectively transmitting by means of a PSK modulated RF signal.

13. The method of claim 9 wherein said n-bit address comprises three digital bits.

14. The method of claim 9 wherein said first and logic level inquiry signals comprise two digital bits.

15. The method of claim 10 wherein said transponder found signal comprises two digital bits.

16. A method for initiating communications with a selected subset of a plurality of transponders in a common RF field of a controller, wherein each of said plurality of transponders has an n-bit address, said method comprising the steps of:

transmitting a series of digital signals from said controller to said transponders corresponding to said n-bit address of said selected subset of said plurality of transponders; and

transmitting a response to said series of digital signals from said selected subset of said plurality of transponders to said controller, said plurality of transponders other than said selected subset of said plurality of transponders entering a reset state.

17. The method of claim 17 wherein said digital signals are transmitted by means of an FSK modulated RF signal.

18. The method of claim 17 wherein said response is transmitted by means of a PSK modulated RF signal.

19. The method of claim 17 wherein said n-bit address comprises three digital bits.

20. The method of claim 17 wherein said digital signals comprise two digital bits.

21. The method of claim 17 wherein said response comprises one digital bit.

22. A communications system for initiating communication between a controller and a selected subset of a plurality of transponders in a common RF field, each of said transponders having an n-bit address, the system comprising:

transmitter means associated with said controller for transmitting a series of digital signals from said controller to said transponders corresponding to said n-bit address of said selected subset of said plurality of transponders;

response means associated with each of said plurality of transponders for transmitting a response to said series of digital signals if said series of digital signals corresponds to said transponder'"'"'s n-bit address; and

reset means associated with each of said plurality of transponders for causing said transponder to enter a reset state if said series of digital signals does not correspond to said transponder'"'"'s n-bit address.

23. The communications system of claim 22 wherein said transmitter means comprises a microprocessor controlled FSK transmit section.

24. The communications system of claim 22 wherein said series of digital signals comprises an FSK modulated signal of substantially 125 KHz-116.3 KHz.

25. The communications system of claim 23 wherein said response means comprises a PSK transmit section.

26. The communications system of claim 22 wherein said response comprises a PSK modulated signal of substantially 62.5 KHz.

27. The communications system of claim 23 wherein said n-bit address comprises three digital bits.

28. The communications system of claim 23 wherein said digital signals comprise two digital bits.

29. The communications system of claim 23 wherein said response comprises one digital bit.