Abstract: A radio frequency identification (RFID) architecture is described. RFID tags are interrogated by a reader, which may be located in a network of readers. The reader transmits symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. An RFID tag includes an antenna pad, a receiver, a state machine, and a modulator. The receiver is coupled to the antenna pad. The receiver receives a symbol from the antenna pad and outputs a received signal. The state machine is configured to determine a response symbol from the received signal and an operating state of the tag. The modulator is coupled to the antenna pad. The modulator is configured to backscatter modulate the received symbol with the response symbol. The modulator is configured to output the backscatter modulated symbol to the antenna pad.

Abstract: The present invention provides methods and apparatuses for demodulation and decoding of backscattered RFID tag signals, represented by their in-phase and quadrature components at the output of the demodulator in the receiver portion of a reader interrogator. Correlation coefficients for the in-phase and quadrature components of the received signal are calculated over a shifted bit interval. Performing a correlation over a shifted bit interval relative to the real bit interval allows the base-band receiver to involve a two-bit interval in making a decision about each transmitted bit. In contrast, in a conventional decoding algorithm, a single bit interval is involved in the decision-making process. Thus, the current method provides a 3 dB energy gain compared to the conventional method. A single zero-mean reference signal is used to compute correlation coefficients, eliminating constant components of the received signal, and simplifying digital implementation of the base-band receiver.

Abstract: Methods, systems and apparatuses for RFID readers forming a reader network are described. In an aspect of the present invention, a plurality of RFID readers are configured to interrogate tags. Furthermore, the readers are configured to communicate with one another. Each of the readers include a ID number which identifies that particular reader within a reader network during communications. Each reader includes a network interface module and an optimization module to receive and process statistical data obtained from other readers in the network. Aspects of the present invention include a ‘primary/secondary’ reader network configuration, as well as a ‘distributed elements’ reader network configuration. A set of operational rules for the environment is indicated, and tag interrogations are optimized according to the rules. Readers may communicate according to a “Listen Before Talk” (LBT) protocol to avoid undesirable interference.

Abstract: Methods, systems and apparatuses for RFID readers forming a reader network are described. In an aspect of the present invention, readers communicate according to a “Listen Before Talk” (LBT) protocol to avoid undesirable interference.

Abstract: An embodiment of the present invention provides a system including a plurality of radio frequency identification (RFID) tags and a reader. Each RFID tag of the plurality of RFID tags backscatter transmits a signal. In one embodiment, the reader includes a plurality of antennas and a signal processor. In another embodiment, the system includes a signal processor and a plurality of readers each including an antenna. In either embodiment, each antenna receives a plurality of signals corresponding to the backscatter transmitted signals. The signal processor combines the received plurality of signals to produce an output signal.

Abstract: Methods, systems, and apparatuses for interacting with radio frequency identification (RFID) tags are described. A tag selector stimulates a sensor of a tag to enable a tag. A tag processor interacts with the enabled tag. The tag processor can test, program, kill, and/or otherwise interact with the tag, while enabled. In this manner large numbers of tags can be interacted with in close proximity, such as during their manufacture in a web format, because the tag selector enables a selected tag (or tags) at any one time.

Abstract: Methods and apparatuses for obtaining data from radio frequency identification (RFID) tags in an efficient manner are described. The method includes the following steps. During the course of an interrogation of an RFID tag population, an RFID tag in the population determines a time slot in which it is designated to respond to a reader. The tag receives signals that are transmitted during the interrogation. The tag determines efficiency-characteristics of the interrogation based on the received signals. The tag autonomously adjusts (e.g., without explicit instructions from the reader) the time slot in which it is designated to respond to the reader based on the efficiency-characteristics.

Abstract: A method of identifying definitions in documents includes receiving text units as an input. Which of the text units includes a cue phrase is then identified. For text units identified as including a cue phrase, localized parsing is performed around the cue phrase to determine whether the text unit including the cue phrase contains a definition.

Abstract: System and methods for optimizing communications between an RFID reader and a population of tags are described. To minimize the amount of data exchanges, the reader and tags use non-sequential bit string or byte masking. In non-sequential bit string masking, the reader transmits an interrogation mask having a plurality of non-sequential sub-masks to the tags. During subsequent collection of the identification sequence, the reader and tags only exchange the non-masked bit positions. The interrogation mask can be determined using superposition processing, historical tendencies, or known identification and/or subset of identification ranges. During superposition processing, the reader determines whether a bit position contains a single value or multiple values for tags in the tag population. If the bit position contains a single value, the bit position is designated as masked. If the bit position contains multiple values, the bit position is designated as non-masked.

Abstract: System and methods for optimizing communications between an RFID reader and a population of tags are described. To increase a read rate, the reader and tags use a partial binary tree traversal. In partial binary tree traversal, a first portion of a tag identification sequence is read. A set marker command is then transmitted to a group of tags causing the tags to set a bit position for start of subsequent binary tree traversal. The subsequent binary tree traversal for the tag group starts at the marked position. Thus, the reader and group of tags negotiate a subset of the identification sequence instead of the entire identification sequence.

Abstract: A method of processing wafers or batches of wafers sequentially in a vacuum chamber (10). The method involves removing a wafer (25) from a location on a support (11); chemically cleaning particles from the support to form volatile components; and placing the subsequent wafer on the cleaned support. The method is performed without a vacuum break.

Abstract: An identification (ID) tag includes a substrate having an input capable of receiving a high frequency signal. For instance, the high frequency signal can be a radio frequency (RF) signal that is generated as part of a radio frequency (RF) ID system. A first charge pump is coupled to the input and is configured to convert the high frequency signal to a substantially direct current (DC) voltage. A data recovery circuit is coupled to the input and is capable of recovering data from the high frequency signal. A back scatter switch is coupled to the input and is capable of modifying an impedance of the input, responsive to a control signal. A state machine is disposed on the substrate and is responsive to the data recovered by the second charge pump, where the state machine is capable of generating the control signal for the back scatter switch in response to the data.

Abstract: A system and methods of language identification of natural language text are presented. The system includes stored expected character counts and variances for a list of characters found in a natural language. Expected character counts and variances are stored for multiple languages to be considered during language identification. At run-time, one or more languages are identified for a text sample based on comparing actual and expected character counts. The present methods can be combined with upstream analyzing of Unicode ranges for characters in the text sample to limit the number of languages considered. Further, n-gram methods can be used in downstream processing to select the most probable language from among the languages identified by the present system and methods.

Abstract: A breathing circuit component includes an inlet, an outlet and an enclosing wall. The enclosing wall defines a gases passageway between the inlet and the outlet. At least a region of the enclosing wall is formed from a breathable material that allows the passage of water vapour without allowing the passage of liquid water or respiratory gases. The breathing circuit component is the expiratory limb of a breathing circuit.

Abstract: A radio frequency identification (RFID) architecture is described. RFID tags are interrogated by a reader, which may be located in a network of readers. The reader transmits symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. An RFID tag includes an antenna pad, a receiver, a state machine, and a modulator. The receiver is coupled to the antenna pad. The receiver receives a symbol from the antenna pad and outputs a received signal. The state machine is configured to determine a response symbol from the received signal and an operating state of the tag. The modulator is coupled to the antenna pad. The modulator is configured to backscatter modulate the received symbol with the response symbol. The modulator is configured to output the backscatter modulated symbol to the antenna pad.

Abstract: A method, system, and apparatus for remotely calibrating data symbols received by a radio frequency identification (RFID) tag population are described. Tags are interrogated by a reader, which may be located in a network of readers. The reader transmits data symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. To calibrate the tags, the reader transmits a plurality of pulses of different lengths to the tag population. The tags receive the plurality of pulses. A characteristic of each pulse, such as a pulse length, is stored by the tags. The stored pulse lengths are used to define different data symbols that are subsequently received by the tags from the reader.

Abstract: Methods and systems for the negotiation of a population of RFID tags with improved security is provided. In one aspect, tags are singulated without using information that directly identifies the tags in the tag population. A key is generated to identify each RFID tag of the population of RFID tags. The generated key does not include bits identifying an item with which the particular RFID tag is associated. An algorithm is operated to identify one or more tags in the population of RFIDs tags using the generated keys. In another aspect, frequency hopping and/or spread spectrum techniques are used to provide improved security while negotiating tags. In another aspect, the reader causes the tags to scroll series of bits back to the reader for each bit sent to the tags to provide improved security.

Abstract: A method, system, and apparatus for communicating with a radio frequency identification (RFID) tag population that includes one or more tags are described. The tags are interrogated by a reader which may be located in a network of readers. The reader interrogates the tags by transmitting data symbols to the tags. Tags respond to the reader with backscatter symbols. Bit patterns, such as identification numbers stored in the tags, are collected from the plurality of tags without collisions. Collisions are avoided because the backscatter symbols transmitted by the tags use different characteristics to represent different data bits. For example, a first backscatter symbol frequency is used by the tag to represent a “0” bit, and a second backscatter symbol frequency is used by the tag to represent a “1” bit.

Abstract: A method, system, and apparatus for interrogating a radio frequency identification (RFID) tag population are described. Tags are interrogated by a reader. The reader and tags engage in communication according to communications algorithms, where data symbols are exchanged between the reader and tags. Furthermore, a reader implicitly controls the operating state of every tag in the tag population by transmitting a single data symbol. Bit patterns may be collected from the tags by the reader, using a variety of interrogation techniques. In a general interrogation, the reader exchanges symbols with the tag population to interrogate the entire tag population. In a specific interrogation, a reader exchanges symbols with the tag population to target a particular tag identification number. Tags may also be placed in a superposition state by the reader, where they respond whenever a received data symbol matches the next bit of their identification number.

Abstract: Methods of constructing a document index including named entity information generated by at least one tool associated with parsing computer programs are presented. The methods include using a lexical analyzer generator, e.g. Flex, and/or a parser generator, e.g. Yacc, to generate named entity recognizers. The named entity recognizers are used to identify named entities in documents, in particular, very large document sets such as web pages available on the Internet. The identified named entities are stored as named entity annotations in the document index. Also, methods of performing searches using the document index are presented. The searches are performed based on queries that can be received on an application programming interface (API). Relevant documents are obtained using the named entity annotations, which can be returned across the API. Also presented are associated computer readable media.