Accurately estimating true bearings of radio frequency identification (RFID) tags associated with items located in a controlled area
First Claim
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1. A radio frequency (RF) identification (RFID) tag reading system for estimating true bearings of RFID tags associated with items in a controlled area, comprising:
- an RFID reader having a plurality of antenna elements, and a plurality of RF transceivers; and
a controller operatively connected to the transceivers, and operative for controlling the transceivers by executing a tag processing module operative for steering a primary transmit beam in the controlled area by transmitting a primary transmit signal via the plurality of the antenna elements to each tag, and for steering a primary receive beam in the controlled area at a primary steering angle along a boresight axis by receiving a primary receive signal via the plurality of the antenna elements from each tag,the controller being further operative for controlling the transceivers by executing a bearing processing module operative for steering at least one secondary receive beam in the controlled area at one secondary steering angle that is offset from the primary steering angle by receiving at least one secondary receive signal via the plurality of the antenna elements from each tag,the controller being further operative for executing the bearing processing module to rotate the at least one secondary receive beam in a cycle around the boresight axis to another secondary steering angle that is offset from the primary steering angle by receiving another secondary receive signal via the plurality of the antenna elements from each tag, andthe controller being further operative for executing the bearing processing module to process the secondary receive signals received in the cycle to estimate a true bearing for each tag in the controlled area.
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Abstract
An RFID tag reading system and method estimate true bearings of RFID tags associated with items in a controlled area. A plurality of secondary receive beams are rotated in a cycle about a boresight axis of a primary receive beam to generate a plurality of secondary receive signals. A controller processes all the secondary receive signals received in the cycle to estimate a true bearing for each tag in the controlled area.
84 Citations
17 Claims
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1. A radio frequency (RF) identification (RFID) tag reading system for estimating true bearings of RFID tags associated with items in a controlled area, comprising:
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an RFID reader having a plurality of antenna elements, and a plurality of RF transceivers; and a controller operatively connected to the transceivers, and operative for controlling the transceivers by executing a tag processing module operative for steering a primary transmit beam in the controlled area by transmitting a primary transmit signal via the plurality of the antenna elements to each tag, and for steering a primary receive beam in the controlled area at a primary steering angle along a boresight axis by receiving a primary receive signal via the plurality of the antenna elements from each tag, the controller being further operative for controlling the transceivers by executing a bearing processing module operative for steering at least one secondary receive beam in the controlled area at one secondary steering angle that is offset from the primary steering angle by receiving at least one secondary receive signal via the plurality of the antenna elements from each tag, the controller being further operative for executing the bearing processing module to rotate the at least one secondary receive beam in a cycle around the boresight axis to another secondary steering angle that is offset from the primary steering angle by receiving another secondary receive signal via the plurality of the antenna elements from each tag, and the controller being further operative for executing the bearing processing module to process the secondary receive signals received in the cycle to estimate a true bearing for each tag in the controlled area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A radio frequency (RF) identification (RFID) tag reading system for estimating true bearings of RFID tags associated with items in a controlled area, comprising:
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an RFID reader mounted at an overhead location in the controlled area, and having a plurality of antenna elements arranged in an array, and a plurality of RF transceivers; a server operatively connected to the RFID reader; and a controller located in at least one of the RFID reader and the server and operatively connected to the transceivers, the controller being operative for controlling the transceivers by executing a tag processing module operative for steering a primary transmit beam in the controlled area by transmitting a primary transmit signal via the plurality of the antenna elements to each tag, and for steering a primary receive beam in the controlled area at a primary steering angle along a boresight axis by receiving a primary receive signal via the plurality of the antenna elements from each tag, the controller being further operative for controlling the transceivers by executing a bearing processing module operative for steering a plurality of secondary receive beams in the controlled area at respective secondary steering angles that are offset from the primary steering angle by receiving a plurality of secondary receive signals via the plurality of the antenna elements from each tag, the controller being further operative for executing the bearing processing module to rotate the plurality of secondary receive beams in a cycle around the boresight axis to other respective secondary steering angles that are offset from the primary steering angle by receiving another plurality of secondary receive signals via the plurality of the antenna elements from each tag, and the controller being further operative for executing the bearing processing module to process all the secondary receive signals received in the cycle to estimate a true bearing for each tag in the controlled area. - View Dependent Claims (10)
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11. A radio frequency (RF) identification (RFID) tag reading method of estimating true bearings of RFID tags associated with items in a controlled area, comprising:
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mounting an RFID reader in the controlled area; operatively connecting a plurality of antenna elements to the RFID reader; operatively connecting a plurality of RF transceivers to a controller; controlling the transceivers by having the controller execute a tag processing module operative for steering a primary transmit beam in the controlled area by transmitting a primary transmit signal via the plurality of the antenna elements to each tag, and for steering a primary receive beam in the controlled area at a primary steering angle along a boresight axis by receiving a primary receive signal via the plurality of the antenna elements from each tag; controlling the transceivers by having the controller execute a bearing processing module operative for steering a plurality of secondary receive beams in the controlled area at respective secondary steering angles that are offset from the primary steering angle by receiving a plurality of secondary receive signals via the plurality of the antenna elements from each tag; controlling the transceivers by having the controller execute the bearing processing module to rotate the plurality of secondary receive beams in a cycle around the boresight axis to other respective secondary steering angles that are offset from the primary steering angle by receiving another plurality of secondary receive signals via the plurality of the antenna elements from each tag; and processing all the secondary receive signals received in the cycle to estimate a true bearing for each tag in the controlled area. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification