Methods and apparatus for locating RFID tags

    公开(公告)号:US12164048B2

    公开(公告)日:2024-12-10

    申请号:US17532521

    申请日:2021-11-22

    Abstract: A radio frequency identification (RFID) system includes an array of antennas to distinguish line-of-sight (LOS) paths from non-line-of-sight (NLOS) paths. The distance between adjacent antennas in the array of antennas is less than half the wavelength of the radio frequency (RF) signal of the system. Each antenna in the antenna array is also digitally controlled to change relative phase difference among the antennas, thereby allowing digital steering of the array of antennas across angles of arrival (AOAs) between 0 and π. The digital steering generates a plot of signal amplitudes as a function of AOAs. LOS paths are distinguished from NLOS paths based on the shapes (e.g., depth, gradient, etc.) of local extremes (e.g., maxima or minima) in the plot.

    ANTENNA ARRAYS AND SIGNAL PROCESSING FOR RFID TAG READERS

    公开(公告)号:US20240330619A1

    公开(公告)日:2024-10-03

    申请号:US18743725

    申请日:2024-06-14

    CPC classification number: G06K7/10356 G06K7/10099 G06K7/10415

    Abstract: Radio-frequency identification (RFID) systems use readers to query and locate passive RFID tags in stores, warehouses, and other environments. An interrogation signal emitted by an antenna array from a reader powers up the tag, which replies by modulating and backscattering incident radiation toward the reader. The antenna array in the reader detects the modulated and backscattered radiation, which is usually several of orders of magnitude weaker than the interrogation signal, as the tag's reply. Unfortunately, crosstalk between the antenna elements in the antenna array limits the reader's sensitivity, which in turn limits the range at which the reader can detect and locate tags. Increasing the pitch of the antenna array to greater than half the wavelength of the interrogation signal reduces crosstalk but introduces grating lobes that produce spurious replies. Fortunately, filtering these spurious replies yields sensitive measurements from an antenna array with a pitch large enough to suppress crosstalk.

    SYSTEMS AND METHODS FOR RFID-BASED RETAIL MANAGEMENT

    公开(公告)号:US20240273986A1

    公开(公告)日:2024-08-15

    申请号:US18585919

    申请日:2024-02-23

    Inventor: Spencer Hewett

    CPC classification number: G08B13/2428 G08B13/2451

    Abstract: A system for RFID-based retail management that includes a set of antennas, an RFID transceiver connected to the set of antennas; and a microprocessor-based system manager that controls the RFID transceiver and transforms RFID response data from the RFID transceiver into RFID tag location data according to read probability methods.

    RFID TAG READERS SWITCHABLE BETWEEN INTERROGATOR AND LISTENER MODES

    公开(公告)号:US20240193381A1

    公开(公告)日:2024-06-13

    申请号:US18556541

    申请日:2022-04-25

    CPC classification number: G06K7/10237 G01S13/08 G01S13/84

    Abstract: Radio-frequency identification (RFID) systems use readers to query and locate passive RFID tags in stores, warehouses, and other environments. A signal from the reader powers up the tag, which modulates and backscatters the signal toward the reader. Unfortunately, the maximum permitted RF signal power, self-interference at the reader, tag sensitivity, and channel loss limit the range at which readers can detect and locate tags. Using multiple readers simultaneously circumvents these limits. When used together, each reader transmits a signal to a tag in turn, and all of the readers listen for each of the tag's responses. The readers that are not transmitting do not experience self-interference and so can detect responses at lower power levels (longer ranges). Because the readers are at different locations, they measure different angles of arrival (AOAs) for each response. These simultaneous measurements can be used to locate each tag faster and with higher fidelity.

    Systems, Devices, and Methods for Secure Booting of RFID Sensors

    公开(公告)号:US20250045409A1

    公开(公告)日:2025-02-06

    申请号:US18925384

    申请日:2024-10-24

    Inventor: David Winn

    Abstract: Radio-frequency identification (RFID) tag readers or sensors interrogate and locate RFID tags in stores, warehouses, and other environments. Unfortunately, these sensors are vulnerable to intrusions, including attacks that can expose any computer network to which the sensors are coupled. Attacks like these can be prevented using a secure booting process for distributing and loading an operating system and/or other software onto each sensor. When the sensor first boots up, it validates a pair of locally stored binary files, e.g., using a pair of locally stored digital keys. Once booted, it establishes a secure connection to a controller, then downloads, validates, and executes a binary file from the controller. Executing the binary file from the controller loads an operating system kernel into the sensor's memory for secure operation.

    SELF-INTERFERENCE CANCELLATION FOR RFID TAG READERS

    公开(公告)号:US20240330614A1

    公开(公告)日:2024-10-03

    申请号:US18574811

    申请日:2022-06-30

    CPC classification number: G06K7/10019 H04B1/0003

    Abstract: A radio-frequency identification (RFID) tag reader interrogates a passive RFID tag by transmitting a signal to the tag, then detecting a much weaker reply at the same carrier frequency from the tag. Unfortunately, self-interference caused by signal leakage within the reader or crosstalk among the reader's antenna elements can make the reply more difficult to detect and limit the range at which the reader can sense tags. A self-interference cancellation circuit in the reader reduces or suppresses the effects of signal leakage and crosstalk, enabling detection of weaker tag replies. The self-interference cancellation circuit can calibrate itself before each transmission to ensure good performance. This improves the reader's sensitivity, increases the reader's range, reduces the reader's power consumption, and/or reduces the minimum required dynamic range of the analog-to-digital converters (ADCs) that digitize the received tag replies.

    METHODS AND APPARATUS FOR LOCATING RFID TAGS

    公开(公告)号:US20220082651A1

    公开(公告)日:2022-03-17

    申请号:US17532521

    申请日:2021-11-22

    Abstract: A radio frequency identification (RFID) system includes an array of antennas to distinguish line-of-sight (LOS) paths from non-line-of-sight (NLOS) paths. The distance between adjacent antennas in the array of antennas is less than half the wavelength of the radio frequency (RF) signal of the system. Each antenna in the antenna array is also digitally controlled to change relative phase difference among the antennas, thereby allowing digital steering of the array of antennas across angles of arrival (AOAs) between 0 and π. The digital steering generates a plot of signal amplitudes as a function of AOAs. LOS paths are distinguished from NLOS paths based on the shapes (e.g., depth, gradient, etc.) of local extremes (e.g., maxima or minima) in the plot.

    Systems and methods for RFID-based retail management

    公开(公告)号:US11043093B2

    公开(公告)日:2021-06-22

    申请号:US15995400

    申请日:2018-06-01

    Inventor: Spencer Hewett

    Abstract: A system for RFID-based retail management that includes a set of antennas, an RFID transceiver connected to the set of antennas; and a microprocessor-based system manager that controls the RFID transceiver and transforms RFID response data from the RFID transceiver into RFID tag location data according to read probability methods.

    Systems and methods for RFID-based retail management

    公开(公告)号:US10013860B2

    公开(公告)日:2018-07-03

    申请号:US14598615

    申请日:2015-01-16

    Inventor: Spencer Hewett

    CPC classification number: G08B13/2428 G08B13/2451

    Abstract: A system for RFID-based retail management that includes a set of antennas, an RFID transceiver connected to the set of antennas; and a microprocessor-based system manager that controls the RFID transceiver and transforms RFID response data from the RFID transceiver into RFID tag location data according to read probability methods.

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