Identification apparatus and methods

Claims

We claim:

1. In a system for multiple device identification and communication of data having an interrogating station for interrogating a plurality of transponders wherein the interrogating station is capable of receiving communications from said transponders via carrier frequencies, each said transponder comprising:

transmitter means adapted, when the transponder is interrogated by the interrogating station, to transmit an information signal via a carrier signal having a frequency selected from a set of possible carrier signal frequencies; and

frequency generating means for selectively generating the set of possible carrier signal frequencies;

the information signal being transmitted successively or repetitively using at each transmission a newly selected carrier signal frequency or set of newly selected carrier signal frequencies;

wherein the frequency of the newly selected carrier signal frequency or set of newly selected carrier signal frequencies is selected independent of external influence and independent of external knowledge by the interrogating station.

2. A transponder as claimed in claim 1, wherein selection of the carrier signal frequency from the set of possible carrier signal frequencies is random.

3. A system as claimed in claim 1, wherein only one carrier signal is selected at each transmission.

4. A system as claimed in claim 1, wherein the transmitter means is adapted to go to an idle state or transmit on a redundant channel in order to provide a break in transmission for a predetermined period of time.

5. A system as claimed in claim 1, wherein each carrier signal generated is assigned a probability weighting in accordance with a desired use of each carrier signal at each transmission.

6. A system as claimed in claim 1, wherein frequency of the set of possible carrier signals is programmed in the transponder from an external source.

7. A system as claimed in claim 1, further comprising a tuned pickup coil adapted to extract power, tuning signal and/or information signals from an externally applied magnetic field.

8. A system as claimed in claim 1, wherein the information signal is a unique signal identifiable with the transponder.

9. An identification system as claimed in claim 1, and including system receiver means for receiving each information signal simultaneously.

10. An identification system as claimed in claim 9, wherein the receiver means further includes logic means for ignoring information signals having the same newly selected frequency.

11. The system of claim 1 wherein the interrogating station is capable of identifying and receiving communications from two or more of said transponders simultaneously.

12. The system of claim 7 wherein the interrogating station is capable of identifying and receiving communications from two or more of said transponders simultaneously.

13. In a system for multiple device identification and communication of data having an interrogating station for interrogating a plurality of transponders wherein the interrogating station is capable of receiving communications from said transponders via carrier frequencies, each said transponder comprising:

logic means adapted to provide an information signal for transmission by said transponder;

transmitter means adapted to transmit the informational signal;

frequency generating means adapted to provide a set of possible carrier signal frequencies greater than two in number, at least one of the carrier signal frequencies being available for transmission of the information signal at each transmission of the information signal; and

carrier signal selection means adapted to select at least on of the carrier signal frequencies from the set of possible carrier signal frequencies at each transmission of the information signal, the frequency selected for each transmission of the information signal being determined internal of the transponder independent of external knowledge and external influence by the interrogating station.

14. A system as claimed in claim 13, wherein upon receipt of an external selection signal, the carrier signal selection means selects or reselects at least one of the carrier signals for transmission.

15. A system as claimed in claim 13, wherein selection of the carrier signal frequency from the set of possible carrier signal frequencies is random.

16. A system as claimed in claim 13, wherein only one carrier signal is selected at each transmission.

17. A system as claimed in claim 13, wherein the transmitter means is adapted to go to an idle state or transmit on a redundant channel in order to provide a break in transmission for a predetermined period of time.

18. A system as claimed in claim 13, wherein each carrier signal generated is assigned a probability weighting in accordance with a desired use of each carrier signal at each transmission.

19. A system as claimed in claim 13, wherein frequency of the set of possible carrier signals is programmed in the transponder from an external source.

20. A system as claimed in claim 13, further comprising a tuned pickup coil adapted to extract power, tuning signal and/or information signals from an externally applied magnetic field.

21. A system as claimed in claim 13, wherein the information signal is a unique signal identifiable with the transponder.

22. An identification system as claimed in claim 13, and including system receiver means for receiving each information signal simultaneously.

23. The system of claim 13 wherein the interrogating station is capable of identifying and receiving communications from two or more of said transponders simultaneously.

24. A system of device identification comprising;

at least two identifiable devices and a device identifier adapted to communicate with said devices by interrogating the devices and receiving data signals from said devices, said identifier adapted to receive signals simultaneously from a plurality of said devices, wherein,

each identifiable device includes transmitter means adapted to transmit a data signal to the identifier,

each transmitter means being adapted to transmit said data signal via a respective carrier signal, the frequency of the carrier signal being selected by each respective device from a predetermined set of carrier signal frequencies greater than two in number, the frequency of each carrier signal being determined internal of each respective device independent of external knowledge and external influence by the identifier.

25. A system as claimed in claim 24, wherein each device is embodied in a VLSI chip.

26. A system as claimed in claim 24, further comprising comparison means adapted to disregard corrupted signals received simultaneously from each device.

27. A system as claimed in claim 24, wherein each device is a passive device.

28. A system as claimed in claim 24, including means for phase coherently generating the newly selected carrier signal using an external powering field as a frequency reference.

29. A system as claimed in claim 24, including means for generating the newly selected carrier signal frequency using at least one phase-locked loop frequency multiplier, and subsequently dividing the carrier signal frequency to obtain a desired frequency of the carrier signal.

30. A system as claimed in claim 29, including means for ignoring frequencies which correspond to harmonics of the powering field.

31. A system as claimed in claim 24, wherein each transmitter means transmits the data signal asynchronously.

32. The system of claim 24 wherein said device identifier is adapted to identify and communicate simultaneously with two or more of said identifiable devices by simultaneously receiving data signals from said two or more identifiable devices.

33. A method of communication between an interrogator and at least one remote device, said method comprising the steps of:

the interrogator interrogating one or more of said remote devices,

each remote device generating a first signal for transmission via a carrier signal at a frequency selected by each respective remote device from a respective predetermined set of carrier signal frequencies, the frequency of the carrier signal being determined by each remote device,

transmitting said first signal from each remote device to the interrogator, and

generating and transmitting the first signal successively or repetitively at each transmission via a new carrier signal, the frequency of the new carrier signal being newly selected internal of each remote device and independent of external knowledge and influence by the interrogator.

34. A method as claimed in claim 33, wherein each remote device transmits the first signal to the interrogator simultaneously.

35. A method as claimed in claim 33, wherein the first signal includes a code unique to each remote device.

36. The method of claim 33 wherein the interrogator identifies and communicates simultaneously with two or more of said remote devices by receiving respective signals simultaneously from said two or more devices.

37. In a system for communication between an interrogating station for interrogating a plurality of transponders wherein the interrogating station includes a receiver that is capable of receiving communication from the transponders via carrier frequencies, wherein each said transponder is adapted for asynchronous communication with the external receiver, said transponder including:

transmitter means adapted to transmit asynchronously at least one signal from the transponder to the external receiver,

frequency generating means adapted to provide a predetermined set of possible carrier frequencies,

the transmitter means being adapted to transmit the at least one signal at a frequency selected from the predetermined set of possible carrier frequencies independent of external knowledge and external influence by said interrogating station.

38. The system of claim 37 wherein the interrogating station is capable of identifying and receiving communications from two or more of said transponders simultaneously.

39. A system as claimed in claim 1, wherein transmission by each transponder is asynchronous.