Radio frequency identification tag and a method of operating same

• US 20070159360A1
• Filed: 01/10/2006
• Published: 07/12/2007
• Est. Priority Date: 01/10/2006
• Status: Active Grant

• Current Assignee: Savi Technology Incorporated
• Original Assignee: Savi Technology Incorporated
• Inventors: Cargonja, Nikola, Ahn, Don, Chan, Joseph
• Granted Patent: US 7,570,176 B2
• Time in Patent Office: Days
• US Class Current: 340/988
• CPC Class Codes: G01S 1/68 Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
• CPC Class Codes: G08G 1/127 to a central station ; Indicators in a central station

Abstract

A tag can transmit a tag signal, and responds to receipt of a wireless signpost signal by determining whether the signpost that generated the signal is currently active. When the signpost is respectively determined to be active and inactive, the tag respectively includes and excludes from the tag signal an information portion that relates to the signpost that generated the received signpost signal. In another configuration, a tag has first and second antennas, receives wireless signpost signals through at least one of the antennas, and responds to receipt of a signpost signal containing antenna select information by causing a selected one of the first and second antennas to be disabled and the other of the first and second antennas to receive wireless signpost signals.

Claims

1. An apparatus comprising a tag having circuitry that includes:

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

a further section responsive to receipt of a signpost signal by said receiver section for determining whether the signpost that generated the received signpost signal is currently active; and

a transmitter section operable to transmit wireless tag signals that each include a tag code associated with said tag, said transmitter section responding to a determination by said further section that the signpost that generated the received signpost signal is currently active by including in at least one said tag signal an information portion that relates to the signpost that generated the received signpost signal, said transmitter section excluding from said tag signals information relating to signposts that are indicated to be inactive.

2. An apparatus according to claim 1, 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.

3. An apparatus according to claim 1, wherein said further section of said tag includes a memory storing a list of signpost codes, and storing an identification of whether each of the signpost codes in the list represents a signpost that has replaced a different signpost.

4. An apparatus according to claim 3, wherein said list is configured as a table.

5. An apparatus according to claim 1, further including:

a signpost configured to transmit wireless signpost signals that each include a signpost code; and

a reader configured to receive the wireless tag signals transmitted by said tag.

6. A method comprising:

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

responding to receipt of a signpost signal by said receiver section by determining in a further section of said tag whether the signpost that generated the received signpost signal is currently active; and

transmitting from a transmitter section of said tag wireless tag signals that each include a tag code associated with said tag, including responding to a determination by said further section that the signpost that generated the received signpost signal is currently active by causing said transmitter section to include in at least one said tag signal an information portion that relates to the signpost that generated the received signpost signal, and responding to a determination by said further section that the signpost that generated the received signpost signal is currently inactive by excluding from said tag signals information relating to inactive signposts.

7. A method according to claim 6, including:

configuring said wireless signpost signals to be near field signals of primarily magnetic character; and

configuring said receiver section to receive said signpost signals of magnetic character.

8. A method according to claim 6, including:

storing a list of signpost codes in said further section of said tag; and

storing an identification of whether each of the signpost codes in the list represents a signpost that has replaced a different signpost.

9. An apparatus comprising a tag having circuitry that includes a receiver section having first and second antennas and configured to receive wireless signpost signals through at least one of said antennas, said receiver section being responsive to receipt of a signpost signal containing antenna select information for causing a selected one of said first and second antennas to be disabled and the other of said first and second antennas to receive wireless signpost signals.

10. An apparatus according to claim 9, 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.

11. An apparatus according to claim 9, wherein said antenna select information identifies one of said first and second antennas.

12. An apparatus according to claim 9, wherein in response to said antenna select information said receiver section determines which of said first and second antennas is to be said selected antenna.

13. An apparatus according to claim 12, wherein said receiver section effects said determining of which of said antennas is to be said selected antenna by comparing the signal strengths currently being received by each of said antennas and then identifying as said selected antenna the one of said first and second antennas having the lowest received signal strength.

14. An apparatus according to claim 9, wherein said receiver section is responsive to a predetermined condition for re-enabling said selected antenna.

15. An apparatus according to claim 14,

wherein said receiver section is configured to receive said signpost signals as near field signals of primarily magnetic character;

and

wherein said predetermined condition includes detection by said receiver section of an absence of a magnetic field.

16. An apparatus according to claim 9, wherein said first and second antennas are oriented to be orthogonal to each other.

17. An apparatus according to claim 9, further including a signpost configured to transmit wireless signpost signals that include antenna select information.

18. A method comprising:

receiving in a receiver section of a tag wireless signpost signals through at least one of first and second antennas of said tag; and

responding to receipt of a signpost signal containing antenna select information for causing said receiver section to disable a selected one of said first and second antennas and to use the other of said first and second antennas to receive wireless signpost signals.

19. A method according to claim 18, including:

configuring said wireless signpost signals to be near field signals of primarily magnetic character; and

configuring said receiver section to receive said signpost signals of magnetic character.

20. A method according to claim 18, including configuring said antenna select information to identify one of said first and second antennas.

21. A method according to claim 18, wherein said responding to receipt of said signpost signal containing said antenna select information includes determining in said receiver section which of said first and second antennas is to be said selected antenna.

22. A method according to claim 21, wherein said determining in said receiver section of which of said first and second antennas is to be said selected antenna includes comparing the signal strengths currently being received by each of said antennas and then identifying as said selected antenna the one of said first and second antennas having the lowest received signal strength.

23. A method according to claim 18, including responding to a predetermined condition by causing said receiver section to re-enable said selected antenna.

24. A method according to claim 23, including:

configuring said receiver section to receive said signpost signals as near field signals of primarily magnetic character; and

selecting as said predetermined condition the detection by said receiver section of an absence of a magnetic field.

25. A method according to claim 18, including orienting said first and second antennas to be orthogonal to each other.