The present invention relates to a position determination apparatus for the position determination of at least one RFID tag, comprising an RFID reader and a control device, wherein the control device is configured to transmit a radio signal by means of the RFID reader, said radio signal exciting an RFID tag to transmit a response signal. The position determination apparatus is movable to different locations from an original position and the control device is configured to transmit a respective radio signal at at least two different locations and to receive the respective response signal or the respective response signals.

The various implementations described herein include methods, devices, and systems for utilizing radar in smart devices. In one aspect, an electronic device includes: (1) circuit boards; (2) a housing encasing the circuit boards; (3) a communications module coupled to the circuit boards, including one or more antennas and configured for communicating with remote devices; (4) a radar module coupled to the circuit boards, configured for generating radar data for a home environment and including: (a) low power radar transmitters; and (b) radar receivers; (5) one or more processors mounted to one of the circuit boards, the processors configured to: (a) govern operation of the communications module and the radar module; (b) determine location and/or movement of detected objects in the home environment; and (c) detect anomalies associated with the detected objects; and (6) a power source coupled to the processors, the communications module, and the radar module.

A transmission apparatus for a wireless device, comprising: an antenna for receiving an original signal and for backscattering a modulated signal containing information from the wireless device; a variable impedance coupled to the antenna, the variable impedance having an impedance value; a delta-sigma modulator coupled to the variable impedance for modulating the impedance value, and thereby a backscattering coefficient for the antenna, in accordance with the information to generate the modulated signal; and, a decoder coupled to the delta-sigma modulator for generating the impedance value from the information.

An RFID tag reading system and method estimate bearings of RFID tags. When the RSSI of a primary and/or secondary RFID receive signal is below a threshold, a primary receive beam is steered in a limited scan to an array of locations distributed around the location at which the RSSI of the primary receive signal is a maximum, and the RSSI of the primary receive signal is recorded at each location. The recorded RSSIs are processed to determine an effective weighted center of distribution of the recorded RSSIs, and the bearing for the tag based on the weighted center of distribution is thus estimated.

An RFID tag reading system and method estimate bearings of RFID tags. When the RSSI of a primary and/or secondary RFID receive signal is below a threshold, a primary receive beam is steered in a limited scan to an array of locations distributed around the location at which the RSSI of the primary receive signal is a maximum, and the RSSI of the primary receive signal is recorded at each location. The recorded RSSIs are processed to determine an effective weighted center of distribution of the recorded RSSIs, and the bearing for the tag based on the weighted center of distribution is thus estimated.

An interrogator and system employing the same. In one embodiment, the interrogator includes a receiver configured to receive a return signal from a tag and a sensing module configured to provide a time associated with the return signal. The interrogator also includes a processor configured to employ synthetic aperture radar processing on the return signal in accordance with the time to locate a position of the tag.

A system comprises a first sensor on a first end of a vehicle and an on-board controller coupled to the first sensor. The first sensor is configured to detect a radio frequency (RF) signature of a marker along a guideway. The first sensor is a radar detection device. The on-board controller is configured to determine a first position of the vehicle on the guideway or a first distance from the position of the vehicle to a stopping location along the guideway based on at least the RF signature received from the first sensor. The marker is a metasurface plate comprising a first diffused element, a first retroreflector element, a first absorbing element and a second diffused element between the first retroreflector element and the first absorbing element.

A system comprises a first sensor on a first end of a vehicle and an on-board controller coupled to the first sensor. The first sensor is configured to detect a radio frequency (RF) signature of a marker along a guideway. The first sensor is a radar detection device. The on-board controller is configured to determine a first position of the vehicle on the guideway or a first distance from the position of the vehicle to a stopping location along the guideway based on at least the RF signature received from the first sensor. The marker is a metasurface plate comprising a first diffused element, a first retroreflector element, a first absorbing element and a second diffused element between the first retroreflector element and the first absorbing element.

A system for determining a location within an area defined by a grid of radio-frequency (RF) tag circuits includes RF exciters that are configured to emit unmodulated RF energy. The grid of the RF tag circuits are configured to receive the unmodulated RF energy from one or more of the RF exciters and to emit modulated RF energy. Each RF tag circuit may store information associated with a location of the RF tag circuit within the area and the modulated RF energy emitted from each RF tag circuit may carry the information.

A system for determining a location within an area defined by a grid of radio-frequency (RF) tag circuits includes RF exciters that are configured to emit unmodulated RF energy. The grid of the RF tag circuits are configured to receive the unmodulated RF energy from one or more of the RF exciters and to emit modulated RF energy. Each RF tag circuit may store information associated with a location of the RF tag circuit within the area and the modulated RF energy emitted from each RF tag circuit may carry the information.