Method and apparatus for varying signals transmitted by a tag

• US 20060077041A1
• Filed: 09/02/2005
• Published: 04/13/2006
• Est. Priority Date: 04/24/2001
• Status: Active Grant

• Current Assignee: Savi Technology Incorporated
• Original Assignee: Savi Technology Incorporated
• Inventors: Chan, Joseph S., Cargonja, Nikola, Anderson, Arthur E. III, Brand, Timothy K., Rajapakse, Ravindra U., Eagleson, James G.
• Granted Patent: US 8,253,541 B2
• Time in Patent Office: Days
• US Class Current: 340/10.400
• CPC Class Codes: G01S 2205/002 for traffic control, mobile tracking, guidance, surveillance or anti-collision
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G06K 17/0022 arrangements or provisious for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L

Abstract

An apparatus (10, 240, 300) includes a signpost (11, 241-256, 322, 612, 623, 626-628, 652, 661, 682, 686, 703) which transmits signpost signals (24) that are received by a tag (12, 271-275, 301-316, 395-397, 616-618, 641-643, 653, 656-657, 662-664, 679, 708, 711). The tag in turn transmits radio frequency beacon signals (72) which are received by a reader (13, 261, 319, 521-530). The tag can vary the duration of the beacon signals, for example in dependence on whether it is currently receiving a signpost signal. Further, the tag can dynamically vary the transmission rate and/or transmission power of the beacon signals, for example following receipt of a signpost signal. Varying these parameters can facilitate compliance with governmental regulations.

Claims

1-20. -20. (canceled)

21. An apparatus comprising a tag having circuitry which includes:

a receiver section operable to receive wireless signpost signals that each include a signpost code; and

a transmitter section operable to transmit wireless beacon signals which each include a beacon code associated with said tag, said transmitter section being responsive to receipt by said receiver section of a respective said signpost signal for including in at least one said beacon signal an information portion that is based on the received signpost signal;

wherein said wireless signpost signals are near field signals of primarily magnetic character, said receiver section being configured to receive said signpost signals of magnetic character.

22. An apparatus according to claim 21, wherein said transmitter section is operable to transmit said beacon signals over a distance substantially greater than a transmission range of said signpost signals.

23. An apparatus according to claim 21, wherein at least part of said signpost signal is subject to one of encryption and password protection.

24. An apparatus according to claim 21, wherein said signpost and beacon signals are transmitted at respective first and second frequencies which are substantially different.

25. An apparatus according to claim 24, wherein said second frequency is substantially higher than said first frequency.

26. An apparatus according to claim 25, wherein said second frequency is selected so that said beacon signal acts as a far field signal, said signpost signal having a roll-off which is several times larger than a roll-off of said beacon signal.

27. An apparatus according to claim 25, wherein said first frequency is approximately 132 KHz.

28. An apparatus according to claim 25, wherein said second frequency is one of approximately 433.92 MHz and approximately 915 MHz.

29. An apparatus according to claim 21, wherein said transmitter section is operable to transmit said beacon signals using a slotted aloha protocol.

30. An apparatus according to claim 21, wherein said signpost signals include an error control portion which is used by said receiver section of said tag to check for errors in each said signpost signal received by said receiver section.

31. An apparatus according to claim 21, wherein said transmitter section is operable to form said beacon signals by effecting modulation of a carrier signal using a Manchester encoded frequency shift keying (FSK) protocol.

32. An apparatus according to claim 21, wherein said signpost signals include amplitude modulation of a carrier signal with an amplitude shift keying (ASK) protocol.

33. An apparatus according to claim 21, wherein said tag further includes a housing having therein said receiver and transmitter sections, and a coupling section capable of physically coupling said housing to a mobile device.

34. An apparatus according to claim 21, wherein said tag includes a battery which powers said circuitry therein.

35. A method, comprising the steps of:

receiving in a receiver section of a tag wireless signpost signals that each include a signpost code, said wireless signpost signals being near field signals of primarily magnetic character; and

transmitting from a transmitter section of said tag wireless beacon signals which each include a beacon code associated with said tag, said transmitting step including the step of causing said transmitter section to be responsive to receipt by said receiver section of a respective said signpost signal for including in at least one said beacon signal an information portion that is based on the received signpost signal.

36. A method according to claim 35, wherein said transmitting step includes the step of transmitting said beacon signals over a distance substantially greater than a transmission range of said signpost signals.

37. A method according to claim 35, including the step of selecting first and second frequencies which are substantially different for said signpost and beacon signals, respectively.

38. A method according to claim 37, wherein said selecting step includes the step of selecting said second frequency to be substantially higher than said first frequency.

39. A method according to claim 38, wherein said selecting step includes the step of selecting said second frequency so that said beacon signal acts as a far field signal, said signpost signal having a roll-off which is several times larger than a roll-off of said beacon signal.

40. A method according to claim 38, wherein said selecting step includes the step of selecting said first frequency to be approximately 132 KHz.

41. A method according to claim 38, wherein said selecting step includes the step of selecting said second frequency to be one of approximately 433.92 MHz and approximately 915 MHz.

42. A method according to claim 35, including the step of providing an error control portion in each said signpost signal, and wherein said receiving step includes the step of causing said receiver section to use said error control portion of each said signpost signal received by said receiver section to check for errors in that signpost signal.

43. An apparatus comprising a tag having circuitry which includes:

a receiver section operable to receive wireless signpost signals that each include a signpost code; and

a transmitter section operable to transmit wireless beacon signals which each include a beacon code associated with said tag, said transmitter section being responsive to receipt by said receiver section of a respective said signpost signal for including in at least one said beacon signal an information portion that is based on the received signpost signal;

wherein said signpost signals also include a command portion, and wherein said tag is responsive to said command portion of a respective said signpost signal received by said tag for effecting a control function within said tag.

44. An apparatus according to claim 43, wherein said control function includes changing a transmit power of said beacon signals.

45. An apparatus according to claim 43, wherein said control function includes placing said tag into one of a normal operational mode and a restricted operational mode, said transmitter section being respectively enabled and disabled in said normal and restricted operational modes.

46. An apparatus according to claim 45, wherein said tag consumes less power in said restricted operational mode.

47. An apparatus according to claim 45, wherein said tag automatically enters said restricted operational mode in the absence of receipt by said tag of any said signpost signal for a predetermined time interval.

48. An apparatus according to claim 43, wherein said control function includes changing a rate of transmission of said beacon signals by said transmission section of said tag.

49. An apparatus according to claim 43, wherein said control function includes changing an operational parameter of said tag.

50. An apparatus according to claim 49, wherein said operational parameter is said beacon code of said tag.

51. An apparatus according to claim 49, wherein said operational parameter is an informational field other than said beacon code which is included in said beacon signals.

52. An apparatus according to claim 49, wherein said operational parameter is one of a password and an encryption code used in association with transmission and reception of at least one of said signpost signals and beacon signals.

53. An apparatus according to claim 43, including:

a signpost which transmits said wireless signpost signals;

a control system having a reader which receives said beacon signals; and

a communication link which facilitates communication between said signpost and said control system, said control system being operable to send instructions to said signpost through said communication link which influence said signpost signals transmitted by said signpost.

54. An apparatus according to claim 53, wherein said instructions sent through said communication link include instructions which control what said signpost uses for said command portion of said signpost signals.

55. A method comprising the steps of:

receiving in a receiver section of a tag wireless signpost signals that each include a signpost code and a command portion;

transmitting from a transmitter section of said tag wireless beacon signals which each include a beacon code associated with said tag, said transmitting step including the step of causing said transmitter section to be responsive to receipt by said receiver section of a respective said signpost signal for including in at least one said beacon signal an information portion that is based on the received signpost signal; and

effecting a control function within said tag in response to said command portion of a respective said signpost signal received by said tag.

56. A method according to claim 55, wherein said step of effecting said control function includes the step of changing a transmit power of said beacon signals.

57. A method according to claim 55, wherein said step of effecting said control function includes the step of placing said tag into one of a normal operational mode and a restricted operational mode, said transmitter section being respectively enabled and disabled in said normal and restricted operational modes.

58. A method according to claim 57, including the step of causing said tag to operate in a manner which consumes less power when said tag is in said restricted operational mode.

59. A method according to claim 57, including the step of causing said tag to automatically enter said restricted operational mode in the absence of receipt by said tag of any said signpost signal for a predetermined time interval.

60. A method according to claim 55, wherein said step of effecting said control function includes the step of changing a rate of transmission of said beacon signals by said transmission section of said tag.

61. A method according to claim 55, wherein said step of effecting said control function includes the step of changing an operational parameter of said tag.

62. A method according to claim 61, including the step of selecting said beacon code of said tag as said operational parameter.

63. A method according to claim 61, including the step of selecting as said operational parameter an informational field other than said beacon code which is included in said beacon signals.

64. A method according to claim 61, including the step of selecting as said operational parameter one of a password and an encryption code used in association with transmission and reception of at least one of said signpost signals and beacon signals.

65. A method according to claim 55, including the steps of:

transmitting said signpost signals from a signpost which is separate from said tag;

receiving said beacon signals in a reader which is a part of a control system separate from said tag;

providing a communication link between said control system and said signpost; and

sending from said control system to said signpost through said communication link instructions which influence said signpost signals transmitted by said signpost.

66. A method according to claim 65, including the step of causing said signpost to vary what said signpost uses for said command portion of said signpost signals as a function of said instructions sent through said communication link.