Systems and methods employing a plurality of signal amplitudes to identify an object

• US 5,864,301 A
• Filed: 05/13/1996
• Issued: 01/26/1999
• Est. Priority Date: 05/13/1996
• Status: Expired due to Fees

• Current Assignee: Jerome D. Jackson
• Original Assignee: Jerome D. Jackson
• Inventors: Jackson, Jerome D.
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Asongwed, Anthony A.
• Application Number:
  US08/645,492
• Time in Patent Office: 988 Days
• Field of Search: 340/855.54, 340/573, 340/825.69, 340/825.72, 340/825.04, 340/825.3, 340/825.31, 342/42, 342/51, 367/2, 367/6
• US Class Current: 340/10.3
• CPC Class Codes: G01S 13/753 using frequency selective elements, e.g. resonator
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2422 using acoustic or microwave tags
• CPC Class Codes: G08B 13/2431 Tag circuit details
• CPC Class Codes: G08B 13/2462 Asset location systems combined with EAS inventory, tracking, logistic G06Q10/00; entrance control systems G07C9/00
• CPC Class Codes: G08B 13/2482 EAS methods, e.g. description of flow chart of the detection procedure
• CPC Class Codes: G08B 13/2485 Simultaneous detection of multiple EAS tags

Abstract

A system and method for identifying objects. A preferred embodiment employs a radio transceiver on each object. Each article is identified by recording an amplitude at which the respective transceiver exhibits a nonlinearity.

Claims

1. In a system including an article having a circuit for receiving an interrogation signal and transmitting a circuit signal, the circuit signal being a function of the interrogation signal, and having a nonlinearity at a first circuit signal frequency, the nonlinearity corresponding to an amplitude level of the interrogation signal, a method comprising the steps of:

detecting the amplitude level by varying an amplitude used to transmit the interrogation signal to the circuit;

detecting a set of other circuit signal frequencies at which the circuit signal has other nonlinearities corresponding to the amplitude level; and

generating, responsive to the set of other circuit signal frequencies, an identification signal for the article.

2. The method of claim 1 wherein the step of detecting the amplitude level includes

causing the interrogation signal to have a first interrogation signal frequency, and the step of detecting a set of other circuit signal frequencies includes

causing the interrogation signal to have other interrogation signal frequencies.

3. The method of claim 1 wherein the generating step includes generating a plurality of digits, each digit corresponding to a respective frequency in the set of other circuit signal frequencies.

4. The method of claim 2 wherein the generating step includes generating a plurality of digits, each digit corresponding to a respective frequency in the set of other circuit signal frequencies.

9. The method of claim 1 wherein the amplitude level is deemed to be a first amplitude level, and the step of detecting a set of other circuit signal frequencies includes

receiving an area signal from an area;

detecting a nonlinearity in the area signal, at a second amplitude level; and

conditionally detecting another nonlinearity of the circuit signal, depending on a function of the first and second amplitude levels.

10. The method of claim 9 further including determining the function in accordance with a difference between the first and second amplitude levels.

11. The method of claim 9 further including determining the function by comparing a number to a difference between the first and second amplitude levels.

12. The method of claim 9 further including determining the function by comparing a number to a difference between the first and second amplitude levels, the number being greater than zero.

13. The method of claim 1 wherein the step of detecting the amplitude level includes

causing the interrogation signal to have a first interrogation signal frequency at a first time, and the step of detecting a set of other circuit signal frequencies includes

causing the interrogation signal to have other interrogation signal frequencies at a time different than the first time.

14. The method of claim 1 wherein the step of detecting the amplitude level is performed before the step of detecting a set of other circuit signal frequencies.

5. In a system including a plurality of articles each having a respective circuit for receiving an interrogation signal and transmitting a respective circuit signal, the circuit signal being a function of the interrogation signal, and having a nonlinearity at a first circuit signal frequency, the nonlinearity corresponding to a respective amplitude level of the interrogation signal, a method comprising the steps of:

detecting, for each circuit, the respective amplitude level by varying an amplitude used to transmit the interrogation signal to the plurality of articles;

detecting, for each circuit, a respective set of other circuit signal frequencies at which the respective circuit signal has other nonlinearities corresponding to the respective amplitude level; and

generating, responsive to the previous step, a respective identification signal for each article.

6. The method of claim 5 wherein the step of detecting the respective amplitude level includes

causing the interrogation signal to have a first interrogation signal frequency, and the step of detecting a respective set of other circuit signal frequencies includes

causing the interrogation signal to have other interrogation signal frequencies.

7. The method of claim 5 wherein the generating step includes generating a respective plurality of digits for each article, each digit corresponding to a respective frequency in the respective set of other circuit signal frequencies.

8. The method of claim 6 wherein the generating step includes generating a respective plurality of digits for each article, each digit corresponding to a respective frequency in the respective set of other circuit signal frequencies.

15. The method of claim 5 wherein the respective amplitude level is deemed to be a first amplitude level, and the step of detecting a respective set of other circuit signal frequencies includes

receiving an area signal from an area;

detecting a nonlinearity, in the area signal, at a second amplitude level; and

conditionally detecting another nonlinearity of the respective circuit signal, depending on a function of the respective first amplitude level and the second amplitude level.

16. The method of claim 15 further including determining the function in accordance with a difference between the respective first amplitude level and the second amplitude level.

17. The method of claim 15 further including determining the function by comparing a number to a difference between the respective first amplitude level and the second amplitude level.

18. The method of claim 15 further including determining the function by comparing a number to a difference between the respective first amplitude level and the second amplitude level, the number being greater than zero.

19. The method of claim 5 wherein the step of detecting the respective amplitude level includes

causing the interrogation signal to have a first interrogation signal frequency at a first time, and the step of detecting a respective set of other circuit signal frequencies includes

causing the interrogation signal to have other interrogation signal frequencies at a time different than the first time.

20. The method of claim 5 wherein the step of detecting the respective amplitude level is performed before the step of detecting a respective set of other circuit signal frequencies.

21. An identification system for a system including an article having a circuit for receiving an interrogation signal and transmitting a circuit signal, the circuit signal being a function of the interrogation signal, and having a nonlinearity at a first circuit signal frequency, the nonlinearity corresponding to an amplitude level of the interrogation signal, the identification system comprising:

a detector that detects the amplitude level by varying an amplitude used to transmit the interrogation signal to the circuit, and that detects a set of other circuit signal frequencies at which the circuit signal has other nonlinearities corresponding to the amplitude level; and

a generator that generates responsive to the set of other circuit signal frequencies, an identification signal for the article.

22. The identification system of claim 21 wherein the detector includes

circuitry that causes the interrogation signal to have a first interrogation signal frequency, and

circuitry that causes the interrogation signal to have other interrogation signal frequencies.

23. The identification system of claim 21 wherein the detector includes

circuitry that causes the interrogation signal to have a first interrogation signal frequency at a first time, and includes

circuitry that causes the interrogation signal to have other interrogation signal frequencies at a time different than the first time.

24. The identification system of claim 23 wherein the generator includes logic that generates a plurality of digits, each digit corresponding to a respective frequency in the set of other circuit signal frequencies.

25. The identification system of claim 21 wherein the generator includes a logic that generates a plurality of digits, each digit corresponding to a respective frequency in the set of other circuit signal frequencies.

26. The identification system of claim 21 wherein the detector includes

a receiver that receives an area signal from an area, and the detector acts to detect a nonlinearity, in the area signal, at a second amplitude level, and conditionally determine that the circuit signal has another nonlinearity, depending on a function of the first and second amplitude levels.

27. The identification system of claim 26 further including logic that determines the function in accordance with a difference between the first and second amplitude levels.

28. The identification system of claim 26 further including logic that determines the function by comparing a number to a difference between the first and second amplitude levels.

29. The identification system of claim 26 further including logic that determines the function by comparing a number to a difference between the first and second amplitude levels, the number being greater than zero.

30. The identification system of claim 21 wherein the detector detects the amplitude level before the detector detects the set of other circuit signal frequencies.

31. An identification system for a system including a plurality of articles each having a respective circuit for receiving an interrogation signal and transmitting a respective circuit signal, the circuit signal being a function of the interrogation signal, and having a nonlinearity at a first circuit signal frequency, the nonlinearity corresponding to a respective amplitude level of the interrogation signal, the identification system comprising:

a detector that detects, for each circuit, the respective amplitude level by varying an amplitude used to transmit the interrogation signal to the plurality of articles, and that detects respective sets of other circuit signal frequencies at which the respective circuit signals have other nonlinearities corresponding to the respective amplitude levels; and

a generator that generates, responsive to each respective set, a respective identification signal for each article.

32. The identification system of claim 31 wherein the detector includes

circuitry that causes the interrogation signal to have a first interrogation signal frequency, and

circuitry that causes the interrogation signal to have other interrogation signal frequencies.

33. The identification system of claim 31 wherein the detector includes

circuitry that causes the interrogation signal to have a first interrogation signal frequency at a first time, and

circuitry that causes the interrogation signal to have other interrogation signal frequencies at a time different than the first time.

34. The identification system of claim 31 wherein the generator includes logic that generates a respective plurality of digits for each article, each digit corresponding to a respective frequency in the respective set of other circuit signal frequencies.

35. The identification system of claim 31 wherein the generator includes logic that generates a respective plurality of digits for each article, each digit corresponding to a respective frequency in the respective set of other circuit signal frequencies.

36. The identification system of claim 31 wherein the amplitude level is deemed to be a first amplitude level, and the detector includes

a receiver that receives an area signal from an area, and the detector acts to detect a nonlinearity, in the area signal, at a second amplitude level corresponding to a second frequency of the interrogation signal, and conditionally determine that the respective circuit signal has another nonlinearity, depending on a function of the respective first amplitude level and the second amplitude level.

37. The identification system of claim 36 further including logic that determines the function in accordance with a difference between the respective first amplitude level and the second amplitude level.

38. The identification system of claim 36 further including logic that determines the function by comparing a number to a difference between the respective first amplitude level and the second amplitude level.

39. The identification system of claim 36 further including logic that determines the function by comparing a number to a difference between the respective first amplitude level and the second amplitude level, the number being greater than zero.

40. The identification system of claim 31 wherein the detector detects the respective amplitude level before the detector detects the respective set of other circuit signal frequencies.