Abstract: A tag communication method includes providing a tag reader operating at a first frequency and having transmit and receive antenna ports, providing a frequency converter module having transmit and receive plugs adapted to directly mate with the transmit and receive ports, and directly mating the transmit plug with the transmit port and the receive plug with the receive port. A transmit signal at the first frequency is received from the reader by the converter module by way of the directly mated transmit plug and converted to a second frequency differing from the first frequency to provide a converted transmit signal which is transmitted to the tag. A receive signal is received from the tag at the second frequency and converted to the first frequency to provide a converted receive signal which is applied by the conversion module to the reader by way of the directly mated receive plug.

Abstract: Methods and systems for localizing an asset using the modulated backscatter from an asset tag and one or more marker tags are described. The system includes the reader, a location module and one or more marker tags. The location estimates for the asset tag are based partially on a prior knowledge of the location of each of the one or more marker tags. The location for each marker tag may be stored in a database. The location module determines a location estimate for the asset tag using the estimated parameters of the modulated backscatter signals received from one or more marker tags and from the asset tag. Using the known locations of the marker tags, a location estimate of the asset tag can be determined. The location estimate may be a relative location, an absolute location, and/or may be a zone including the marker tags. A mobile reader using the marker tags can localize asset tags throughout a large area and may, for example, take an inventory of assets throughout the large area.

Abstract: A backscatter tag system including a tag having tag circuitry and a reader for transmitting a command signal to the tag includes an energizer node for transmitting an energy signal to the tag to energize the tag and provide energy for operating the tag circuitry and for emitting a backscatter signal by the tag. The energizer node includes an energizer receiver for receiving the command signal from the reader to provide a received command signal and an energizer transmitter for transmitting the received command signal from the reader to the tag. The energizer node transmits both the energy signal and the received command signal to the tag. The energizer transmitter can transmit a sinusoidal signal, a frequency hopping signal, a spread spectrum signal, or a frequency shifted signal to the tag. The backscatter tag circuitry can include a processor.

Abstract: A reader includes a single receiver circuit and a switching circuit coupled to the single receiver circuit. A first antenna connection is coupled to the switching circuit, wherein the first antenna connection is configured to receive a first signal from a source of radio frequency waves. A second antenna connection is coupled to the switching circuit, and the second antenna connection is configured to receive a second signal from the source of radio frequency waves. A processor is configured to determine angle of arrival information in accordance with the first and second signals. The processor is further configured to determine relative phase information in accordance with the first and second signals. Additionally, the processor is configured to localize the source of radio frequency waves in accordance with the angle of arrival information. The switching circuit includes a multiplexer selectively coupling the first and second antenna connections to the single receiver circuit.

Abstract: A localization method for use in a tag communication system includes associating a supertag having a plurality of tags with an item, reading backscatter signals from the tags of the plurality of tags to provide a plurality of backscatter signals, estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters, and localizing the item in accordance with the plurality of derived signal parameters. The backscatter signals are read by a tag reader having a single antenna and the item is localized in accordance with an antenna array technique performed upon the plurality of derived signal parameters. The backscatter signals are read with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags, and the item is localized in accordance with the further pluralities of derived signal parameters.

Abstract: A tag communication method includes providing a tag reader operating at a first frequency and having transmit and receive antenna ports, providing a frequency converter module having transmit and receive plugs adapted to directly mate with the transmit and receive ports, and directly mating the transmit plug with the transmit port and the receive plug with the receive port. A transmit signal at the first frequency is received from the reader by the converter module by way of the directly mated transmit plug and converted to a second frequency differing from the first frequency to provide a converted transmit signal which is transmitted to the tag. A receive signal is received from the tag at the second frequency and converted to the first frequency to provide a converted receive signal which is applied by the conversion module to the reader by way of the directly mated receive plug.

Abstract: A tag communication method includes providing a tag reader operating at a first frequency and having transmit and receive antenna ports, providing a frequency converter module having transmit and receive plugs adapted to directly mate with the transmit and receive ports, and directly mating the transmit plug with the transmit port and the receive plug with the receive port. A transmit signal at the first frequency is received from the reader by the converter module by way of the directly mated transmit plug and converted to a second frequency differing from the first frequency to provide a converted transmit signal which is transmitted to the tag. A receive signal is received from the tag at the second frequency and converted to the first frequency to provide a converted receive signal which is applied by the conversion module to the reader by way of the directly mated receive plug.

Abstract: A localization method for use in a tag communication system includes associating a supertag having a plurality of tags with an item, reading backscatter signals from the tags of the plurality of tags to provide a plurality of backscatter signals, estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters, and localizing the item in accordance with the plurality of derived signal parameters. The backscatter signals are read by a tag reader having a single antenna and the item is localized in accordance with an antenna array technique performed upon the plurality of derived signal parameters. The backscatter signals are read with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags, and the item is localized in accordance with the further pluralities of derived signal parameters.

Abstract: A reader includes a single receiver circuit and a switching circuit coupled to the single receiver circuit. A first antenna connection is coupled to the switching circuit, wherein the first antenna connection is configured to receive a first signal from a source of radio frequency waves. A second antenna connection is coupled to the switching circuit and configured to receive a second signal from the source of radio frequency waves. A processor is configured to determine angle of arrival information in accordance with the first and second signals. The processor is further configured to determine relative phase information in accordance with the first and second signals. Additionally, the processor is configured to localize the source of radio frequency waves in accordance with the angle of arrival information. The switching circuit includes a multiplexer selectively coupling the first and second antenna connections to the single receiver circuit.

Abstract: In an RFID system with existing reader and tags communicating with each other, appliqués derive information by listening to this communication to yield significant performance benefits, while not affecting the communication between the existing nodes. For example, an appliqué capable of receiving beamforming can estimate the angle of arrival of the signal emitted by a tag, thereby providing information that can be used to localize the tag. An appliqué may be connected to an existing reader by means of an existing port, such as to an antenna port or to an Ethernet port. The information from appliqués can be integrated with that obtained from existing nodes at either the appliqués, or further up the hierarchy in middleware.

Abstract: A tag communication method includes providing a tag reader operating at a first frequency and having transmit and receive antenna ports, providing a frequency converter module having transmit and receive plugs adapted to directly mate with the transmit and receive ports, and directly mating the transmit plug with the transmit port and the receive plug with the receive port. A transmit signal at the first frequency is received from the reader by the converter module by way of the directly mated transmit plug and converted to a second frequency differing from the first frequency to provide a converted transmit signal which is transmitted to the tag. A receive signal is received from the tag at the second frequency and converted to the first frequency to provide a converted receive signal which is applied by the conversion module to the reader by way of the directly mated receive plug.

Abstract: A localization method for use in a tag communication system includes associating a supertag having a plurality of tags with an item, reading backscatter signals from the tags of the plurality of tags to provide a plurality of backscatter signals, estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters, and localizing the item in accordance with the plurality of derived signal parameters. The backscatter signals are read by a tag reader having a single antenna and the item is localized in accordance with an antenna array technique performed upon the plurality of derived signal parameters. The backscatter signals are read with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags, and the item is localized in accordance with the further pluralities of derived signal parameters.

Abstract: A backscatter tag system including a tag having tag circuitry and a reader for transmitting a command signal to the tag includes an energizer node for transmitting an energy signal to the tag to energize the tag and provide energy for operating the tag circuitry and for emitting a backscatter signal by the tag. The energizer node includes an energizer receiver for receiving the command signal from the reader to provide a received command signal and an energizer transmitter for transmitting the received command signal from the reader to the tag. The energizer node transmits both the energy signal and the received command signal to the tag. The energizer transmitter can transmit a sinusoidal signal, a frequency hopping signal, a spread spectrum signal, or a frequency shifted signal to the tag. The backscatter tag circuitry can include a processor.

Abstract: One or more readers transmit radio frequency (RF) beacons to be electronically reflected by tags. Data transmitted via modulated backscatter from radio frequency identification (RFID) tags is encoded so as to permit reliable demodulation of simultaneous transmissions from multiple tags. This includes the use of spreading sequences as in direct sequence spread spectrum, where the spreading sequences may be a function of the tag ID, or may be randomly chosen. Backscattered signals from multiple tags may be detected using well-known receiver techniques for code division multiple access (CDMA) systems. Readers may be equipped with transmit and/or receive antenna arrays. A receive antenna array permits a reader to estimate directions of arrival for received signals, as well as to enhance range by performing receive beamforming.

Abstract: Systems and methods for beamforming in radio frequency identification (RFID) applications are disclosed. A beamforming system uses a distributed architecture and techniques for antenna beamforming using a feedback control loop to direct radio frequency (RF) energy onto a specific region, referred to as an interrogation zone, which includes a calibration node where one or more RFID tags may be located. The distributed architecture of the beamforming system is resistant to fading and shadowing effects, providing accurate RFID reader operation even in environments with multi-path reflections or environmental changes, such as people moving around or changes in the location of equipment.

Abstract: In an RFID system with existing reader and tags communicating with each other, appliqués derive information by listening to this communication to yield significant performance benefits, while not affecting the communication between the existing nodes. For example, an appliqué capable of receiving beamforming can estimate the angle of arrival of the signal emitted by a tag, thereby providing information that can be used to localize the tag. An appliqué may be connected to an existing reader by means of an existing port, such as to an antenna port or to an Ethernet port. The information from appliquéscan be integrated with that obtained from existing nodes at either the appliqués, or further up the hierarchy in middleware.

Abstract: Methods and systems for localizing an asset using the modulated backscatter from an asset tag and one or more marker tags are described. The system includes the reader, a location module and one or more marker tags. The location estimates for the asset tag are based partially on a prior knowledge of the location of each of the one or more marker tags. The location for each marker tag may be stored in a database. The location module determines a location estimate for the asset tag using the estimated parameters of the modulated backscatter signals received from one or more marker tags and from the asset tag. Using the known locations of the marker tags, a location estimate of the asset tag can be determined. The location estimate may be a relative location, an absolute location, and/or may be a zone including the marker tags. A mobile reader using the marker tags can localize asset tags throughout a large area and may, for example, take an inventory of assets throughout the large area.