A method of addressing one or more RFID devices within a group of RFID devices includes transmitting a command to respond to the group at a first modulation depth. The method further includes receiving a response from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth. The method further includes transmitting the command to respond to the group at a second modulation depth higher than the first modulation depth. The method further includes receiving a response from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth. The method is also directed to authenticating RFIDs by comparing a measured minimum modulation depth to a known minimum modulation depth.

A noncontact communication medium includes a coil and a processor mounted on a magnetic tape cartridge. The processor communicates with a communicatee by coupling between the coil and the communicatee by electromagnetic induction through an external magnetic field applied from the communicatee. The communicatee merges a command into the external magnetic field. The processor executes processing corresponding to the command merged into the external magnetic field. The processor changes a response time of the processor in response to the command, according to a characteristic of at least one of the magnetic tape cartridge, the noncontact communication medium, or the communicatee.

A method for streaming sensor data from a set of radio-frequency identification (RFID) tags includes determining an initial communication approach to be performed with respect to each RFID tag. The method also includes managing access to the RFID tag by refining the initial communication approach based on records of successes and failures of the initial communication approach. A radio-frequency identification (RFID) system is also disclosed, the system comprising one or more processors and a memory system comprising one or more non-transitory computer-readable media storing instructions that, when executed by at least one of the one or more processors, causes the system to perform operations for streaming sensor data from one or more RFID tags to one or more RFID readers.

The invention relates to local positioning and more particularly to methods of searching and registering tags in a local positioning system. A method of registering tags in a local positioning system is provided. Registering is performed in near-field mode. Tag stores identifying data of the local positioning system. Positioning unit stores identifying data of the tag. Furthermore, a method of searching a tag registered in a local positioning system is provided. Positioning units send address search packets into the space of the local positioning system. Desired tag responds with a positioning pulse. There is also provided a method of searching identifying data of a tag not registered in a local positioning system. Positioning units send broadcast search packets into the space of the local positioning system. Bisection method is used to detect identifying data of the tag. The invention can reduce power consumption by the tag and the positioning unit, and eliminate overlapping the signals received from a plurality of tags.

Various embodiments illustrated herein disclose a method. The method includes receiving, by a first radio-frequency identification (RFID) tag in an RFID reader, a first interrogation command from another RFID reader. The method includes transmitting, by the first RFID tag in the RFID reader, a first response signal to the other RFID reader in response to the reception of the first interrogation command. The method further includes transmitting, by a processor in the RFID reader, a second interrogation command to one or more second RFID tags, where the transmission of the second interrogation command is concurrent to the reception of the first interrogation command or the transmission of the first response signal.

A method for interleaving time slots in a multi-antenna system for communication with RFID tags is described. An exemplary system has a first RFID interrogator and first and second antennas. The first and second antennas direct signals to and receive signals from respective first and second interrogation zones. A first interrogation signal is transmitted to the first antenna. A first acquire window for receiving a signal from a first RFID transponder is opened after the first interrogation signal. A second interrogation signal is transmitted to the second antenna after the first interrogation signal, and a second acquire window for receiving a signal from a second RFID transponder is opened after the second interrogation signal.

Various embodiments illustrated herein disclose a method. The method includes receiving, by a first radio-frequency identification (RFID) tag in an RFID reader, a first interrogation command from another RFID reader. The method includes transmitting, by the first RFID tag in the RFID reader, a first response signal to the other RFID reader in response to the reception of the first interrogation command. The method further includes transmitting, by a processor in the RFID reader, a second interrogation command to one or more second RFID tags, where the transmission of the second interrogation command is concurrent to the reception of the first interrogation command or the transmission of the first response signal.

A method for interleaving time slots in a multi-antenna system for communication with RFID tags is described. An exemplary system has a first RFID interrogator and first and second antennas. The first and second antennas direct signals to and receive signals from respective first and second interrogation zones. A first interrogation signal is transmitted to the first antenna. A first acquire window for receiving a signal from a first RFID transponder is opened after the first interrogation signal. A second interrogation signal is transmitted to the second antenna after the first interrogation signal, and a second acquire window for receiving a signal from a second RFID transponder is opened after the second interrogation signal.

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.

Various embodiments illustrated herein disclose a method. The method includes receiving, by a first radio-frequency identification (RFID) tag in an RFID reader, a first interrogation command from another RFID reader. The method includes transmitting, by the first RFID tag in the RFID reader, a first response signal to the other RFID reader in response to the reception of the first interrogation command. The method further includes transmitting, by a processor in the RFID reader, a second interrogation command to one or more second RFID tags, where the transmission of the second interrogation command is concurrent to the reception of the first interrogation command or the transmission of the first response signal.