Method and apparatus for varying signals transmitted by a tag

• US 8,253,541 B2
• Filed: 09/02/2005
• Issued: 08/28/2012
• 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, Eagleson, James G., Anderson, III, Arthur E., Brand, Timothy K., Rajapakse, Ravindra U.
• Primary Examiner(s): BROWN, VERNAL U
• Application Number:
  US11/219,357
• Publication Number:
  US 20060077041A1
• Time in Patent Office: 2,552 Days
• Field of Search: 340/10.4, 340/905, 340/572.4, 340/572.1, 340/505
• US Class Current: 340/10.4
• 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 provisions 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. An apparatus comprising a tag having circuitry which includes:

a receiver section configured to receive near field wireless signpost signals of primarily magnetic character transmitted at a first frequency allowing transmission over a first distance, the received signpost signals including a signpost code and the first distance is up to about twelve (12) feet; and

a transmitter section configured to transmit wireless beacon signals to a remote reader at a second frequency allowing transmission over a second distance, the transmitted wireless beacon signals including 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 the first distance is less than the second distance and the second frequency is different from the first frequency and substantially higher than the first frequency.

2. An apparatus according to claim 1, wherein said transmitter section is configured to transmit said beacon signals over the second distance which is up to about three hundred (300) feet.

3. An apparatus according to claim 1, wherein at least part of said signpost signal is subject to one of encryption and password protection.

4. An apparatus according to claim 1, 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.

5. An apparatus according to claim 1, wherein said first frequency is approximately 132 KHz.

6. An apparatus according to claim 1, wherein said second frequency is one of approximately 433.92 MHz and approximately 915 MHz.

7. An apparatus according to claim 1, wherein said transmitter section is configured to transmit said beacon signals using a slotted aloha protocol.

8. An apparatus according to claim 1, 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.

9. An apparatus according to claim 1, wherein said transmitter section is configured to form said beacon signals by effecting modulation of a carrier signal using a Manchester encoded frequency shift keying (FSK) protocol.

10. An apparatus according to claim 1, wherein said signpost signals include amplitude modulation of a carrier signal with an amplitude shift keying (ASK) protocol.

11. An apparatus according to claim 1, 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.

12. An apparatus according to claim 1, wherein said tag includes a battery which powers said circuitry therein.

13. A method, comprising the steps of:

receiving, in a receiver section of a tag, wireless signpost signals that each include a signpost code transmitted at a first frequency allowing transmission over a first distance that is up to about twelve (12) feet, said wireless signpost signals being near field signals of primarily magnetic character; and

transmitting from a transmitter section of said tag wireless beacon signals to a remote reader at a second frequency that is different from and greater than the first frequency and allows transmission over a second distance that is greater than the first distance 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.

14. A method according to claim 13, wherein said transmitting step includes the step of transmitting said beacon signals over the second distance which is up to about three hundred (300) feet.

15. A method according to claim 13, 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.

16. A method according to claim 13, wherein said selecting step includes the step of selecting said first frequency to be approximately 132 KHz.

17. A method according to claim 13, wherein said selecting step includes the step of selecting said second frequency to be one of approximately 433.92 MHz and approximately 915 MHz.

18. A method according to claim 13, 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.

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

a receiver section configured to receive wireless signpost signals that each include a digital word having bits serially modulated onto a predetermined carrier frequency using amplitude modulation, the digital word comprising a preamble, a signpost code, a flag, an error control portion, and a command portion separate and mutually exclusive of the preamble, the command portion including a tag command field, a control command field, and a parameter field, wherein the parameter field includes a parameter for implementing a command specified by the control command field; and

a transmitter section configured to transmit wireless beacon signals which each include a digital beacon word associated with said tag, the digital beacon word including a preamble, a format field, a tag type field including information related to the use of the tag, an error control field, a beacon code, and an asset type field, said transmitter section being responsive to receipt by said receiver section of a respective said signpost signal for further including in the digital beacon word the received signpost code and the received tag command field or control command field as a confirmation that the tag has received the tag command or control command;

wherein said tag is responsive to said command portion of a respective said digital word received by said tag for effecting a control function within said tag.

20. An apparatus according to claim 19, wherein said control function includes changing a transmit power of said beacon signals.

21. An apparatus according to claim 19, 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.

22. An apparatus according to claim 21, wherein said tag consumes less power in said restricted operational mode.

23. An apparatus according to claim 21, 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.

24. An apparatus according to claim 19, wherein said control function includes changing a rate of transmission of said beacon signals by said transmission section of said tag.

25. An apparatus according to claim 19, wherein the parameter for implementing a command specified by the control command field comprises an operational parameter of said tag.

26. An apparatus according to claim 25, wherein said operational parameter is said beacon code of said tag.

27. An apparatus according to claim 25, wherein said operational parameter is an informational field other than said beacon code which is included in said beacon signals.

28. An apparatus according to claim 25, 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.

29. An apparatus according to claim 19, 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.

30. An apparatus according to claim 29, wherein said instructions sent through said communication link include instructions which control what said signpost uses for said command portion of said signpost signals.

31. A method comprising the steps of:

receiving in a receiver section of a tag wireless signpost signals that each include a digital word having bits serially modulated onto a predetermined carrier frequency using amplitude modulation, the digital word comprising a preamble, a signpost code, a flag, an error control portion, and a command portion separate from and mutually exclusive of said preamble, the command portion including a tag command field, a control command field, and a parameter field, wherein the parameter field includes a parameter for implementing a command specified by the control command field;

transmitting from a transmitter section of said tag wireless beacon signals which each include a digital beacon word associated with said tag, the digital beacon word including a preamble, a format field, a tag type field including information related to the use of the tag, an error control field a beacon code, and an asset type field, 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 further including in the digital beacon word the received signpost code and the received tag command field or control command field as a confirmation that the tag has received the tag command or control command; and

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

32. A method according to claim 31, wherein said step of effecting said control function includes the step of changing a transmit power of said beacon signals.

33. A method according to claim 31, 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.

34. A method according to claim 33, 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.

35. A method according to claim 33, 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.

36. A method according to claim 31, 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.

37. A method according to claim 31, wherein said step of effecting said control function includes the step of changing an operational parameter specified by the parameter field of said tag.

38. A method according to claim 37, including the step of selecting said beacon code of said tag as said operational parameter.

39. A method according to claim 37, including the step of selecting as said operational parameter an informational field other than said beacon code which is included in said beacon signals.

40. A method according to claim 37, 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.

41. A method according to claim 31, 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.

42. A method according to claim 41, 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.