A method by which a hub unit can discover IDs from a plurality of satellite units across a shared communication link that connects each of the satellite units to the hub unit, each satellite unit having a satellite unit ID, the method comprising the hub unit broadcasting a message over the shared communication link, the message including an ID segment with a string of bits shorter than a bit length of the satellite unit IDs and an ID segment location; and each satellite unit receiving the broadcast message and comparing the ID segment with an ID portion of its own satellite unit ID starting at the ID segment location, if the ID portion for a satellite unit matches the ID segment, the satellite unit transmitting its complete satellite unit ID to the hub unit over the shared communication link.

A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGO RFID backscatter transponders, SEGO RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

A reading system includes an evaluation value acquirer and a determining processor. The evaluation value acquirer is configured to acquire, with regard to a reading device configured to perform wireless communication with an electronic tag attached to each of one or more items by using a radio wave as a medium to read item information on each of one or more items, an evaluation value about at least one of: the number of times; a time interval; or a frequency, of reading the item information for each of at the one or more items. The determining processor is configured to determine, for each of the one or more items, whether or not each of the one or more items is an object to be read based on a change in the evaluation value over time.

Systems and methods for determining an inventory. The methods comprise: placing an RFID tag in a first operational mode in which at least one communication operation or device of the RFID tag is disabled or bypassed; performing first operations by the RFID tag to determine when it is time to begin communications in accordance with the time slotted communications scheme; transitioning an operational mode of the RFID tag from the first operational mode to a second operational mode in which the communication operation(s) or device of the RFID tag is enabled or no longer bypassed, in response to a determination that it is time for the RFID tag to begin communications; and transitioning the operational mode of the RFID tag back into the first operational mode when the RFID tag's communications with a remote tag reader for inventory determination purposes are complete or a time slot has expired.

What is described is an Radio Frequency Identification (RFID) tag configured for communicating with an Radio Frequency Identification (RFID) reader, wherein the RFID tag is configured to receive a query command from the RFID reader, to measure a duration of a TRcal signal comprised by the query command, and to determine an individual Backscatter Link Frequency for communicating with the RFID reader based on the measured duration of the TRcal signal. The invention also refers to an RFID reader and to a corresponding method.

A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGOTM RFID backscatter transponders, SEGOTM RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

A method of interrogating a plurality of RFID tags comprises interrogating a first RFID tag with a read command comprising a masking value for a predefined portion of a User Memory Bank of the first RFID tag. The predefined portion stores state information for the first RFID tag. The masking value corresponds to a non-quiesced state relative to the read command interrogation. The method further comprises receiving a response from the first RFID tag that indicates that the first RFID tag is in the non-quiesced state. The method further comprises interrogating the first RFID tag with a write command that instructs the first RFID tag to write a predefined value to the predefined portion of the User Memory Bank, wherein writing the predefined value to the predefined portion places the first RFID tag in a quiesced state relative to a subsequent read command interrogation comprising the masking value.

Response parameters for a population of RFID tags present in an inventory space are determined by (a) continuously scanning the inventory space to interrogate the population of RFID tags and receiving responses from RFID tags within the population; (b) after multiple responses have been received from a specific RFID tag, determining response times for the specific RFID tag corresponding to time periods between sequential ones of the multiple responses from the specific RFID tag, (c) calculating a maximum acceptable response time based at least in part on the response times determined in step (b); and (c) recording a response interval data set including one or more of the response times determined in step (b) and the maximum acceptable response time calculated in step (c).

Provided is a technology that enables a plurality of sensor information to be synchronized for a technology of a sensor management device communicating with a plurality of wireless sensors in a time division manner. A sensor management device includes a transmission unit that transmits acquisition start instructions for starting acquisitions of sensor information to a plurality of wireless sensors respectively at different timings; and an extraction unit that extracts a plurality of common period sensor information that the plurality of wireless sensors have acquired in the common period from the plurality of sensor information with reference to deviation of times at which the transmission unit has transmitted the acquisition start instructions to the plurality of wireless sensors.

An RFID system comprises an array of antennas each configured to emit a plurality of beams in different directions. The beams of each pair of adjacent antennas are directed towards one another and overlap. A pair of adjacent antennas transmits simultaneously and the overlapping beams interfere to create an interference pattern. An RFID reader controls the relative phase and/or frequency of the beams to move the interference pattern to read an RFID tag within the moving pattern. As the chance of a RFID tag responding to an emitted beam generally increases with signal strength of the reader beam an area of constructive interference means that RFID tags in that region are more likely to respond to the signal. The system can cover a large proportion of the area below ceiling-mounted antennas, where cover generally means that RFID tags in that area will be successfully read.