Provided are a tag, interrogator, and system for performing position measurement based on backscatter in a millimeter-wave band. In detail, provided is a tag including a planar Van Atta array antenna, a frequency-shift keying (FSK) modulator connected to the planar Van Atta array antenna, and at least one bias circuit connected to the FSK modulator, wherein the FSK modulator is configured to, based on an interrogation signal being received by the planar Van Atta array antenna, modulate the interrogation signal based on a control signal supplied through the at least one bias circuit, and output the modulated interrogation signal in a direction from which the interrogation signal is received, through the planar Van Atta array antenna.

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.

Interactive parking facilities may include one or more computer displays or other output devices for providing information to occupants of vehicles arriving at the parking facilities, and for providing information to workers tasked with delivering items to such occupants. A vehicle and/or an occupant may be identified at a parking space, and an ordered item associated with the vehicle or the occupant may then be placed in a staging area. Instructions to deliver the item from the staging area to the vehicle may be displayed to a worker, and information regarding the pending arrival of the item may be displayed to the occupant, on one or more computer displays. Thus, the fulfillment of an order may be triggered upon detecting the arrival of the vehicle at a parking space, and the delivery of the one or more items to the vehicle may be guided based on such information.

A backscatter tag communicate device includes, in part, a receiver configured to receive a WiFi packet conforming to a communication protocol defining a multitude of codewords, a mapper configured to map at least a first subset of the multitude of codewords disposed in the packet to a second multitude of codewords defined by the protocol, and a frequency shifter configured to shift a frequency of the second multitude of codewords such that the frequency shifted codewords are characterized by a single sideband spectrum. The communication protocol may be the 802.11b communication protocol. The mapper may optionally map the first subset of the multitude of codewords by changing phases of the first subset of the multitude of codewords.

A flexible fabric RFID tag is disclosed wherein a conductor is embedded into a flexible material to form a channel. The channel does not extend through the total depth of the flexible material. The conductor placed in the channel forms an antenna for an RFID tag when coupled to an RFID chip. The channel allows the conductor to be buried into the flexible material to prevent uncomfortable ridges and to create a flat printable surface.

A mobile device determines its location accurately by measuring the range to a position reflector as well as azimuth and elevation angles of arrival (AOA) at the reflector. The mobile can transmit a coded radar signal and process reflections to determine its location. The reflectors may include internal delays that can identify the reflector and provide transmit/receive separation for the mobile. The reflection can include a primary and further delayed secondary reflection. The mobile can determine the internal delay of the reflector based on the delay between primary and secondary reflections. The range and AOA information can be combined with information about the position, orientation, and characteristics of the reflectors to determine location. In some systems, the mobile device can determine its location in a three-dimensional space using reflections from only one reflector. The reflectors, which can be economically produced, can be unpowered and low profile for easy installation.

Embodiments generally relate to robots and enabling robots to locate objects in a physical environment. In some embodiments, a method includes charging a radio-frequency identification (RFID) tag with an RFID reader, where the RFID tag is coupled to an object, and where the RFID reader is coupled to a robot arm. The method further includes receiving a plurality of responses from the RFID tag, where each response includes a power value to which the RFID tag was charged and a time value for charging the RFID tag to the power value. The method further includes moving the RFID reader to a plurality of RFID reader positions using the robot arm, where each RFID reader position is associated with one of the responses of the plurality of responses. The method further includes determining a plurality of distances from the RFID reader to the RFID tag based on power values and the time values of the respective responses at the respective RFID reader positions. The method further includes determining a location of the RFID tag based on the plurality of distances.

A multi-protocol, multi-band array antenna system may be used in Radio Frequency Identification (RFID) system reader and sensory networks. The antenna array may include array elements with an integrated low noise amplifier. The system may employ digital beam forming techniques for transmission and steering of a beam to a specific sensor tag or group of tags in a cell. The receive beam forming network is optimized for detecting signals from each sensor tag. Narrow and wideband interferences may be excised by an interference nulling algorithm. Space division multiplexing may be used by the antenna system to enhance system processing capacity.

A method of determining a rate of penetration of a downhole tool. The method comprises introducing a downhole tool including a drill bit configured to drill through a subterranean formation in a wellbore, the downhole tool comprising at least one reader configured to communicate with identification tags using electromagnetic radiation. The method includes advancing the wellbore with the drill bit and placing, with a component of a bottomhole assembly of the downhole tool, a first identification tag at a first location proximate the wellbore and at least a second identification tag at a second location proximate the wellbore and separated from the first location by a distance. An interrogation signal is transmitting from the at least one reader toward a wall of the wellbore and response signals from the identification tags are received by the at least one reader to determine proximity of the identification tags to the reader. A rate of penetration of the downhole tool is determined, using a processor and associated memory, based at least in part on a distance between identification tags and an amount of time between receiving response signals from a first identification tag and at least a second identification tag. Downhole systems for determining a rate of penetration and other methods are also disclosed.

In a configuration for detection of a movement state of a radio tag using a phase difference of a response wave from the radio tag, a phase [i] and a measurement time t[i] of a response wave from a radio tag measured are sequentially stored in a memory. A difference from a previous phase and a difference from a previous measurement time with respect to each phase [i] stored in the memory are calculated as a phase difference [i] and a time difference t[i]. A phase addition value sum[i] obtained by cumulatively adding a plurality of the phase differences [i] is calculated so as to correct a phase difference in which the corresponding time difference t[i] among the calculated plurality of the phase differences [i] exceeds a time threshold tsa [i], whereby the movement state of the radio tag is detected based upon the calculated phase addition value sum[i].