Synthetic aperture RFID handheld with tag location capability
First Claim
1. A radio frequency identification (RFID) reader comprising:
- a sensor configured to measure movement of the RFID reader;
a first antenna that transmits a first radio frequency (RF) query to an RFID tag within range of the first antenna;
a receiver that receives a response from the RFID tag at each moved position of the RFID reader in response to the first RF query; and
a processor that;
receives data from the sensor indicating positions of the RFID reader when the RFID is being moved;
determines a phase for the tag response at each moved position of the RFID reader;
calculates a change in phase of the tag signal as a function of time using the determined phases; and
calculates a bearing for the tag using the calculated change in phase and a location of the RFID reader as provided by the sensor.
0 Assignments
0 Petitions
Accused Products
Abstract
A system for determining a bearing or location of a radio frequency identification (RFID) tag using a handheld RFID reader is described. In one embodiment, the reader is equipped with an accelerometer. A user moves the reader while the reader receives the tag'"'"'s signal and determines the tag signal'"'"'s phase at multiple locations. The locations of the reader antenna can be reconstructed using the accelerometer data. By using the phase determined at multiple locations in conjunction with the location of the reader antenna, the reader can determine the bearing of the tag. For an RFID reader not equipped with an accelerometer, the sign and ratio of the rate of change in the phase of a tag'"'"'s signal to the distance traveled by the reader antenna can be used to determine the location of the tag relative to the reader.
-
Citations
19 Claims
-
1. A radio frequency identification (RFID) reader comprising:
-
a sensor configured to measure movement of the RFID reader; a first antenna that transmits a first radio frequency (RF) query to an RFID tag within range of the first antenna; a receiver that receives a response from the RFID tag at each moved position of the RFID reader in response to the first RF query; and a processor that; receives data from the sensor indicating positions of the RFID reader when the RFID is being moved; determines a phase for the tag response at each moved position of the RFID reader; calculates a change in phase of the tag signal as a function of time using the determined phases; and calculates a bearing for the tag using the calculated change in phase and a location of the RFID reader as provided by the sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A system comprising:
-
a radio frequency identification (RFID) reader comprising; a first antenna that is configured to transmit a first radio frequency (RF) query to an RFID tag; and a receiver that receives responses of the RFID tag while the RFID reader is being moved in response to the first RF query; and a processor that is configured to; determine phases of the tag responses; calculate a change of phase from at least two of the responses of the RFID tag as a function of time using the determined phases; and calculate a bearing for the tag using the calculated change of phase of the RFID tag and a location of the RFID reader. - View Dependent Claims (10, 11, 12, 13, 14, 15)
-
-
16. A method of determining a location of a radio frequency identification (RFID) tag relative to an RFID reader, the method comprising:
-
providing an antenna configured to send a first RF query to an RFID tag; receiving a response of the RFID tag to the first RF query in response to the RFID reader moving in a first direction; calculating, by a processor, a phase of the response of the RFID tag; calculating a position of the tag using the calculated phase of the RFID tag and a location of the RFID reader; outputting the calculated position of the tag; and providing an indication of the change of phase. - View Dependent Claims (17, 18, 19)
-
Specification