Localization using virtual antenna arrays in modulated backscatter RFID systems

• US 8,446,253 B2
• Filed: 03/08/2010
• Issued: 05/21/2013
• Est. Priority Date: 03/11/2009
• Status: Expired due to Fees

• Current Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Original Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Inventors: Ramchandran, Kannan, Wild, Ben J., Tkachenco, Artem, Madhow, Upamanyu
• Primary Examiner(s): Phan, Hai
• Assistant Examiner(s): Knox, Kaleria
• Application Number:
  US12/719,126
• Publication Number:
  US 20100309017A1
• Time in Patent Office: 1,170 Days
• Field of Search: 340/572.5, 340/572.1, 340/10.5, 340/825.49, 340/10.1, 340/8.1, 340/10.11
• US Class Current: 340/8.1
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14

Abstract

A localization method for use in a tag communication system includes associating a supertag having a plurality of tags with an item, reading backscatter signals from the tags of the plurality of tags to provide a plurality of backscatter signals, estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters, and localizing the item in accordance with the plurality of derived signal parameters. The backscatter signals are read by a tag reader having a single antenna and the item is localized in accordance with an antenna array technique performed upon the plurality of derived signal parameters. The backscatter signals are read with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags, and the item is localized in accordance with the further pluralities of derived signal parameters.

Claims

1. A localization method for use in a tag communication system, comprising:

associating a tag with an item;

interrogating said tag by a reader which receives in turn a plurality of backscatter signals equally-spaced in time during movement of said reader;

estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters; and

localizing the item in accordance with the plurality of derived signal parameters.

2. The localization method for use in a tag communication system of claim 1, wherein the backscatter signals are read by a tag reader having a single antenna further comprising localizing the item in accordance with an antenna array technique performed upon the plurality of derived signal parameters.

3. The localization method for use in a tag communication system of claim 1, further comprising:

reading the backscatter signals with an antenna array to provide a further plurality of derived signal parameters for each tag reader location of the plurality of tag reader locations; and

localizing the item in accordance with the further pluralities of derived signal parameters.

4. The localization method for use in a tag communication system of claim 1, further comprising calibrating the plurality of derived signal parameters in accordance with the further pluralities of derived signal parameters.

5. The localization method for use in a tag communication system of claim 1, further comprising:

repeating said step of interrogating said tag by a reader which receives in turn a plurality of backscatter signals equally-spaced in time during movement of said reader, said repetition occurring at location different from said first interrogation.

6. The localization method for use in a tag communication system of claim 1, wherein the tag is a marker tag further comprising determining a tag reader location in accordance with the plurality of signal parameters.

7. The localization method for use in a tag communication system of claim 5, wherein said movement of said reader is a linear movement.

8. The localization method for use in a tag communication system of claim 5, wherein said reader is moved at a constant velocity.