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 radio frequency transmission method and a device thereof are provided. The method includes: transmitting a radio frequency command by a radio frequency reader; receiving the radio frequency command by a radio frequency tag, wherein the radio frequency command includes bits; determining a logic level of each of the bits based upon a time length of each of the bits at a voltage level of a voltage waveform by the radio frequency tag; and determining whether to transmit a response signal in response to the radio frequency reader based upon the logic level of each of the bits by the radio frequency tag.

A system, exhibiting a communication station for communicating with a number of radio tags in a time slot communication process, in which a number of time slots per time slot cycle in a repeating sequence are available for communication, and each time slot is characterized by a distinct time slot symbol, wherein the communication station is designed to send out a synchronization data signal exhibiting the time slot symbol for the currently present time slot, and wherein a radio tag is designed for changing from a sleep state into an active state at a wakeup instant, and for receiving the synchronization data signal in the active state and, if the received time slot symbol indicates a time slot intended for it, for defining a new wakeup instant corresponding to the next appearance of the time slot intended for it in a time slot cycle that follows the currently present time slot cycle.

A system, exhibiting a communication station for communicating with a number of radio tags in a time slot communication process, in which a number of time slots per time slot cycle in a repeating sequence are available for communication, and each time slot is characterized by a distinct time slot symbol, wherein the communication station is designed to send out a synchronization data signal exhibiting the time slot symbol for the currently present time slot, and wherein a radio tag is designed for changing from a sleep state into an active state at a wakeup instant, and for receiving the synchronization data signal in the active state and, if the received time slot symbol indicates a time slot intended for it, for defining a new wakeup instant corresponding to the next appearance of the time slot intended for it in a time slot cycle that follows the currently present time slot cycle.

A multiple identity (ID) tag device is provided. The multiple ID tag device comprises an antenna, a power harvesting circuit electrically coupled to the antenna and configured to receive RF energy collected by the antenna and convert the RF energy into electrical power, a demodulation circuit electrically coupled to the antenna, a modulation circuit electrically coupled to the antenna, a selector circuit electrically coupled to the power harvesting circuit, the demodulation circuit, and the modulation circuit and configured to receive a first signal from the demodulation circuit, send a second signal to the modulation circuit, and receive electrical power from the power harvesting circuit, and a plurality of ID storage circuits electrically coupled to the selector circuit, each ID storage circuit configured to receive the first signal from the selector circuit, send the second signal to the selector circuit, and receive the electrical power from the selector circuit.

A radio frequency identification method and a reader, the reader comprises a camera, a display screen, a distance sensor, an antenna unit and a processor, the camera is configured to collect an image of a target electronic tag, and the display screen is configured to display an image of the target electronic tag, the distance sensor is configured to measure the distance d between the target electronic tag and the reader, and the antenna unit is configured to receive a radio frequency signal emitted by the target electronic tag. When the antenna unit only receives a radio frequency signal transmitted by one electronic tag, the reader reads the electronic tag; when the antenna unit receives radio frequency signals transmitted by a plurality of electronic tags, the processor filters out the target electronic tag according to the matching degree between the distance and a phase value of the radio frequency signal.

Methods, systems, apparatus, and articles of manufacture are disclosed to improve radio frequency identification (RFID) tag communication. An example disclosed apparatus includes an RFID reader monitor to activate a first RFID reader and deactivate a second RFID reader during a first tag data acquisition at a first time, and deactivate the first RFID reader and activate the second RFID reader during a second tag data acquisition at a second time, a tag logger to identify a first set of RFID tags detected by the first RFID reader at the first time, and identify a second set of RFID tags detected by the second RFID reader at the second time, and a group generator to improve RFID tag communication by identifying which one of the first RFID reader and the second RFID reader communicates with a common RFID tag.

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.

RFID tags are used for many purpose including tracking RFID interrogators are used to retrieve information from tags. In many applications, RFID interrogators and RFID tags remain stationary during interrogation. Regions of low energy due to interference from either additional antenna or reflections from RFID tags and objects can impede or prohibit the reading of RFID tags residing in such regions. Stirring of the generated electromagnetic field is a method of moving around the regions of low energy, where tags can not be read, during the interrogation process. Mechanical stirring is accomplished by introducing a conductor into the electromagnetic field and moving it about in the field. Solid state stirring is accomplished by introducing a variable conductor into the field and varying the conductivity of the variable conductor. Mathematical stirring is accomplished by use of a plurality of antenna and controlling the phase difference between the antenna in a configuration known as phased antenna arrays.

A radio frequency transmission method and a device thereof are provided. The method includes: transmitting a radio frequency command by a radio frequency reader; receiving the radio frequency command by a radio frequency tag, wherein the radio frequency command includes bits; determining a logic level of each of the bits based upon a time length of each of the bits at a voltage level of a voltage waveform by the radio frequency tag; and determining whether to transmit a response signal in response to the radio frequency reader based upon the logic level of each of the bits by the radio frequency tag.