Abstract: The present disclosure is directed to a system and method for multiplexing radio frequency signals. In some implementations, a system includes a host coupling module, a plurality of antennas, and a processing module. The host coupling module is configured to receive and transmit RF signals through a wired connection. The plurality of antennas are configured to wirelessly transmit RF signals and receive RF signals from RFID tags. The processing module is configured to selectively switch between the plurality of antennas for communication with the RFID tags using the host coupling module and backscatter at least a portion of the received RF signals through the wired connection to communicate information independent of an internal power supply.

Abstract: The present disclosure is directed to a system and method for converting between different radio frequencies. In some implementations, a method includes receiving a request from a Radio Frequency Identification Device (RFID) reader configured to communicate with a first type of RFID tag. Independent of digital signal processing, the received request is automatically converted to a request compatible with a second type of RFID tag different from the first type of RFID tag. The converted request is transmitted to an RFID tag of the second type of RFID tag.

Abstract: The present disclosure includes a system and method for conducting radio frequency signals using multiple layers. In some implementations, a signal transfer element configured to passively transfer RF signals between a first region and a second region includes a first conductor layer having a first continuous conductor configured as a first portion of a first antenna, a transmission line, and a first portion of a second antenna. The first antenna and the second antenna are configured to wirelessly receive and transmit Radio Frequency (RF) signals. The signal transfer element also includes a second conductor layer having a second continuous conductor configured as a second portion of the first antenna, a ground plane, and a second portion of the second antenna.

Abstract: The disclosure includes a system and method for oversampling and digitally filtering RFID signals. In some implementations of the present disclosure, an RF receiver includes an ADC, a comb filter, and a mask filter. The ADC is operable to directly sample an RF signal independent of a band pass filter and convert the RF signal to a digital signal. The RF signal is sampled at a rate greater than or equal to 60 MHz. The comb filter is coupled to the ADC. The mask filter is coupled to the comb filter. The comb filter and frequency mask filter are configured to filter out-of-band noise in the digital signal.

Abstract: The present disclosure is directed to a system and method for backscattering different radio frequency protocols. In some implementations, a radio Frequency (RF) tag includes an antenna and a storage module. The antenna is configured to receive an RF signal from any of a plurality of readers. Each reader is associated with a different protocol having different time durations. The storage module is coupled to the antenna and configured to store energy associated with the RF signal. In addition, the storage module substantially maintains a voltage in the tag during any of the different time durations independent of an internal power supply.

Abstract: The present disclosure is directed switching RFID tags. In some implementations, the RFID system includes an RFID tag and a panel. The panel includes one or more contacts configured to move between a first position and a second position. The second position forms an electrical connection between the RFID tag and the one or more contacts to update a state of the RFID tag.

Abstract: The present disclosure includes a system and method for reducing leakage noise in directly sampled radio frequency signals. In some implementations, a Radio Frequency IDentification (RFID) reader includes an antenna, an Analog-to-Digital Converter (ADC), a synthesizer module, and a Carrier Noise Reduction (CNR) module. The antenna is configured to receive Radio Frequency (RF) signals and pass the RF signals to a receive path. The ADC is configured to directly sample RF signals in the receive path in accordance with a clock signal and generate a digital signal. The synthesizer module is configured to generate the clock signal and a signal used to upconvert a transmitter signal. The clock signal and the upconversion signal are phase locked. The CNR module is configured to reduce leakage noise in the receive path.

Abstract: A method and system for tracking each item in a cluster of items. Each item has an associated item ID. The method and system involve the following steps. Storing a plurality of item records. The plurality of item records includes, for each item in the cluster of items, an associated item record for storing the associated item ID for the item. Each item record in the plurality of records is then linked to the other item records in the plurality of item records. Using the associated item record for each item in the threshold number of items, and the link between each item record and the other item records, the item records for the associated item ID of each item in the cluster that are not in the threshold number of items are determined.

Abstract: The present disclosure is directed to a system and method for multiplexing radio frequency signals. In some implementations, a system includes a host coupling module, a plurality of antennas, and a processing module. The host coupling module is configured to receive and transmit RF signals through a wired connection. The plurality of antennas are configured to wirelessly transmit RF signals and receive RF signals from RFID tags. The processing module is configured to selectively switch between the plurality of antennas for communication with the RFID tags using the host coupling module and backscatter at least a portion of the received RF signals through the wired connection to communicate information independent of an internal power supply.

Abstract: A method for use in a RFID reader, the method comprising providing an output signal from an amplifier of a transmitter, attenuating the output signal via a step attenuator, detecting and comparing the attenuated output signal to a reference value, and adjusting power to the amplifier until the attenuated output signal is substantially equal to the reference value. The attenuated output signal drives a local oscillator signal of a receiver thereby canceling noise generated by the transmitter in the receiver.

Abstract: The present disclosure is directed to a system and method for directly sampling RF signals. In some implementations, an RF reader includes a clock generator and an Analog-to-Digital Converter (ADC). The clock generator is configured to generate a sample clock signal based, at least in part, on an input signal associated with transmitting RF signals. The ADC is configured to directly sample RF signals in a receive path of the reader using the sample clock signal to generate a digital signal. Mixing of the RF signal and the sample clock, through the sampling process in the ADC, reduces phase noise associated with the transmission signal in the receive path.

Abstract: An RFID circuit comprises an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate an in-phase and a quadrature phase component of the RF carrier signal, a switch coupled to the hybrid operable to pass one of the in-phase and quadrature phase components of the RF carrier signal to its output, and a mixer coupled to the output of the switch operable to multiply one of the in-phase and quadrature phase component of the carrier signal and a received modulated carrier signal and generate a baseband signal.

Abstract: An RFID circuit comprises an RF carrier signal source, and a hybrid coupled thereto operable to generate first, second and third phase-shifted RF carrier signals. The circuit further comprises first, second, and third mixers coupled to the hybrid each operable to multiply one of the first, second and third respective carrier signals and a backscattered modulated carrier signal and generate first, second and third baseband signals, respectively. The circuit further comprises first, second, and third delay lines respectively coupled to the first, second, and third mixers and operable to generate first, second and third delayed baseband signals. The circuit further comprises logic coupled to the first, second, and third mixers and the first, second, and third delay lines and operable to detect substantially simultaneous data transitions in at least two of the first, second, and third baseband signals, and generating a reconstructed signal having a data transition in response thereto.

Abstract: A method and system for tracking each item in a cluster of items. Each item has an associated item ID. The method and system involve the following steps. Storing a plurality of item records. The plurality of item records includes, for each item in the cluster of items, an associated item record for storing the associated item ID for the item. Each item record in the plurality of records is then linked to the other item records in the plurality of item records. Using the associated item record for each item in the threshold number of items, and the link between each item record and the other item records, the item records for the associated item ID of each item in the cluster that are not in the threshold number of items are determined.

Abstract: The present disclosure includes a system and method for adjusting parameters associated with leakage signals. In some implementations, an RFID reader includes an RF antenna, a transmitter section, a receiver section, a control module and a cancellation noise reduction (CNR) section. The transmitter section is coupled to the RF antenna and operable to generate a transmit signal to be transmitted by the RF antenna. The receiver section is coupled to the RF antenna and operable to receive a receive signal from the RF antenna. In addition, the receiver section further includes a de-rotation module and a control module. The de-rotation module is operable to de-rotate, by ?, an in-phase signal and quadrature signal associated with the leakage signal. The control module is operable to generate control signals used to produce a signal for reducing the leakage signal in a receive path of the reader. The CNR section is operable to subtract from the reduction signal from the leakage signal.

Abstract: An apparatus comprises a transmitter, a receiver, an antenna and a signal cancellation circuit. The transmitter is configured to send a transmitter signal associated with a frequency. The receiver is associated with the frequency. The antenna is coupled to the transmitter and the receiver. The signal cancellation circuit is coupled to the transmitter, the receiver and the antenna. The signal cancellation circuit is configured to phase shift a first portion of the transmitter signal to produce a phase-shifted signal. The signal cancellation circuit is configured to combine the phase-shifted signal with a second portion of the transmitter signal to produce a combined signal. The second portion of the transmitter signal is associated with a reflection of a third portion of the transmitter signal from the antenna. The first portion, the second portion and the third portion of the transmitter signal are different from each other.

Abstract: The disclosure includes a system and method for oversampling and digitally filtering RFID signals. In some implementations of the present disclosure, an RF receiver includes an ADC, a comb filter, and a mask filter. The ADC is operable to directly sample an RF signal independent of a band pass filter and convert the RF signal to a digital signal. The RF signal is sampled at a rate greater than or equal to 60 MHz. The comb filter is coupled to the ADC. The mask filter is coupled to the comb filter. The comb filter and frequency mask filter are configured to filter out-of-band noise in the digital signal.

Abstract: An RFID circuit comprising an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals, first and second mixers coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively, and first logic coupled to the first and second mixers operable to select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal.

Abstract: An RFID circuit comprises an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate an in-phase and a quadrature phase component of the RF carrier signal, a switch coupled to the hybrid operable to pass one of the in-phase and quadrature phase components of the RF carrier signal to its output, and a mixer coupled to the output of the switch operable to multiply one of the in-phase and quadrature phase component of the carrier signal and a received modulated carrier signal and generate a baseband signal.

Abstract: A reader for a radio frequency identification system capable of simultaneously reading tags operating a multiple frequencies. The reader includes a radio frequency module for each operating frequency of the tags. The radio frequency modules are coupled to a bus which is connected to an interrogator control module. Each of the radio frequency modules receives the return signal from the tags at the associated operating frequency and converts the return signal into a pulse sequence. The interrogator control module locks to and decodes the pulse sequence according to the protocol associated with the tag type.