Localizing a tag using variable signal range

• US 8,044,804 B1
• Filed: 06/01/2007
• Issued: 10/25/2011
• Est. Priority Date: 06/01/2007
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: McReynolds, Alan A.
• Primary Examiner(s): Lee, Benjamin C
• Assistant Examiner(s): PHAM, QUANG
• Application Number:
  US11/756,697
• Time in Patent Office: 1,607 Days
• Field of Search: 340/572.8, 340/568, 340/568.3, 340/568.4, 340/568.1, 340/568.2, 340/572.1, 340/572.2, 340/572.3, 3405724-5727, 342/118, 342/825.49, 235/375
• US Class Current: 340/572.4
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56

Abstract

A method for localizing a tag includes activating an antenna to transmit an RF signal and monitoring for a responsive signal transmitted by the tag. The signal range of the RF signal transmitted by the antenna may be altered if a responsive signal from the tag is not received. The method further includes detecting the responsive signal transmitted by the tag after the tag receives the RF signal transmitted at the altered signal range.

Claims

1. A method of localizing a plurality of cables with a reader device having a plurality of loop antennas, said method comprising:

placing a plurality of radio frequency identification (RFID) tags near ends of the plurality of cables;

placing the plurality of loop antennas over a plurality of respective cable sockets configured to receive the ends of the plurality of cables, wherein each of the plurality of loop antennas comprises an opening and is positioned to receive a cable end through the opening;

activating at least one of the plurality of antennas to transmit an RF signal at a first signal range;

determining whether a responsive signal is received from at least one of the RFID tags;

altering the signal range of the at least one of the plurality of antennas to a second signal range in response to a determination that a responsive signal has not been received from at least one of the RFID tags;

determining whether a responsive signal is received from at least one of the RFID tags; and

in response to a determination that a responsive signal has been received from at least one of the RFID tags, localizing the position of the at least one of RFID tag and at least one cable on which the at least one tag has been positioned based upon the signal range at which the responsive signal from the tag was received.

2. The method of claim 1, wherein activating the at least one of the plurality of antennas to transmit the RF signal includes providing power to the at least one of the plurality of antennas at a first level and, wherein altering the signal range of the RF signal transmitted by the at least one of the plurality of antennas comprises:

providing power to the at least one of the plurality of antennas at a second level, which is different from the first level.

3. The method of claim 1, wherein localizing the tag and the cable further comprises:

identifying the signal range at which the responsive signal was received from the tag; and

correlating the identified signal range with the position of the tag.

4. The method of claim 3, wherein localizing the tag and the cable further comprises:

correlating data encoded in the responsive signal with a power level provided to the at least one of the plurality of antennas, wherein the power level provided to the at least one of the plurality of antennas is the power level which generated the second signal range.

5. The method of claim 1, further comprising:

activating a second antenna to transmit a second RF signal, wherein the RF signal and the second RF signal overlap.

6. The method of claim 5, further comprising:

detecting a second responsive signal transmitted by the tag, wherein the second responsive signal is transmitted by the tag in response to the tag receiving the second RF signal.

7. The method of claim 6, further comprising:

comparing a first power level at which the antenna received the responsive signal from the tag with a second power level at which the second antenna received the second responsive signal from the tag.

8. The method of claim 7, further comprising:

determining which of the first power level and the second power level is the lowest; and

determining that the tag is closer to one of the antenna and the second antenna based upon which of the first power level and the second power level is the lowest.

9. The method of claim 1, wherein altering the signal range of the antenna to the second signal range comprises:

one of increasing and decreasing the size of the antenna.

10. The method of claim 1, wherein altering the signal range of the antenna to the second signal range comprises:

repositioning the antenna to provide one of a stronger and a weaker RF signal in a particular direction.

11. A system for localizing a plurality of cables, said system comprising:

a plurality of cable sockets;

a plurality of radio frequency identification (RFID) tags placed near ends of the plurality of cables, wherein the ends of the plurality of cables are configured to be inserted into respective ones of the plurality of cable sockets;

a reader device having a plurality of loop antennas, each of said plurality of loop antennas being positioned over at least one of the plurality of cable sockets and comprising an opening and being positioned to receive a cable end through the opening, and wherein the reader device is operable to selectively activate at least one antenna of the plurality of antennas to transmit a radio frequency (RF) signal from the at least one antenna, wherein the reader device is further operable to,

selectively alter a signal range of the transmitted RF signal to a plurality of different signal ranges,

determine whether a responsive signal from a tag has been received at each of the plurality of different signal ranges,

receive a responsive signal transmitted by the tag, wherein the tag transmits the responsive signal in response to receiving the RF signal transmitted by the at least one antenna at one of the plurality of different signal ranges, and

localize the tag and a cable on which the tag has been placed by correlating the received responsive signal with the one of the plurality of different signal ranges that resulted in eliciting the responsive signal.

12. The system of claim 11, wherein the reader device is operable to selectively alter the signal range of the transmitted RF signal by selectively varying an amount of power provided to the at least one antenna.

13. The system of claim 12, wherein the one of the plurality of different signal ranges that resulted in the receipt of the responsive signal is proportional to the amount of power provided to the at least one antenna which transmitted the one of the plurality of different signal ranges.

14. The system of claim 11, wherein the plurality of antennas are arranged in an array.

15. The system of claim 14, wherein the plurality of antennas are configured to be selectively activated to transmit overlapping RF signals.

16. The system of claim 11, wherein the reader device is further configured to localize the tag based upon the signal range at which the responsive signal was received from the tag.

17. The system of claim 11, wherein the plurality of RFID tags are positioned substantially near the centers of the loop antennas.

18. The system of claim 11, wherein the reader device is further operable to,

activate a second antenna from the plurality of antennas to transmit a second RF signal from the second antenna,

receive a second responsive signal transmitted by at least one of the plurality of tags, wherein the plurality of tags are configured to transmit the second responsive signal in response to receiving the second RF signal transmitted by the second antenna,

compare a first power level at which the antenna received the responsive signal from the tag with a second power level at which the second antenna received the second responsive signal from the tag;

and

determine which of the first power level and the second power level is the lowest.

19. The system of claim 18, wherein the reader device is further operable to localize the tag based upon which of the first power level and the second power level is the lowest.

20. A non-transitory computer readable storage medium on which is embedded one or more computer programs, said one or more computer programs implementing a method for localizing a plurality of cables with a reader device having a plurality of loop antennas, wherein each of the plurality of loop antennas comprises an opening and is positioned to receive a cable end through the opening, said one or more computer programs comprising a set of instructions for:

activating at least one of the plurality of antennas to transmit an RF signal at a first signal range directed toward one or more tags placed on one or more of the plurality of cables;

determining whether a responsive signal is received from at least one of the one or more tags;

altering the signal range of the antenna to a second signal range in response to a determination that a responsive signal has not been received from at least one of the one or more tags;

determining whether a responsive signal is received from the at least one of the one or more tags; and

in response to a determination that a responsive signal has been received from the tag, localizing the tag and the cable on which the tag has been placed based upon the signal range at which the responsive signal from the tag was received.