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 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: The present disclosure is directed to determining speeds of radio frequency tags. In some implementations, a method includes sampling a Radio Frequency (RF) signal from an RFID tag at a plurality of different times as the RFID tag approaches an RFID reader and recedes from the RFID reader. A phase of the RF signal is determined for each of the plurality of different times based, at least in part, on the sampled RF signal. A speed of the RFID tag is determined based, at least in part, on the determined phase for the sampled signal for each of the plurality of different times.

Abstract: Adaptive transmission of a tag activation signal and detection of a tag. By monitoring the effects of a load on a tag activation signal, a signal analyzer adjusts the transmission waveform from which the signal is generated so that the next tag activation signal transmitted into the load more closely corresponds to a desired activation signal.

Abstract: A method for controlling electronic article surveillance (EAS) transmissions is described. The method includes calculating system parameters associated with one or more of a desired frequency a desired duty cycle, and a desired phase difference between antennas for a transmitter, and initializing a counter with a value based on the system parameters. The method also includes comparing a count from the counter to the system parameters, and modulating EAS transmission signals based on the comparison between the count and the system parameters. An EAS transmitter and an EAS system are also described.

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: A system and method for providing wireless synchronized operation of electronic article surveillance (EAS) systems are provided. The method may include communicating wirelessly between each of a plurality of controllers connected to a plurality of detectors of the plurality of EAS systems and receiving with a communications receiver of each of the controllers wireless communications from at least some of the other plurality of controllers. The communications receiver may be separate from a tag detection receiver.

Abstract: The present disclosure is directed to a system and method for sampling intermediate radio frequencies. In some implementations, a method for RF communication includes receiving an analog Radio Frequency (RF) signal. The analog RF signal is downconverted to an analog signal centered at an Intermediate Frequency (IF). The analog IF signal is converted to a digital signal centered at an IF. The digital IF signal is downconverted to a digital baseband signal.

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 for controlling electronic article surveillance (EAS) transmissions is described. The method includes calculating system parameters associated with one or more of a desired frequency, a desired duty cycle, and a desired phase difference between antennas for a transmitter, and initializing a counter with a value based on the system parameters. The method also includes comparing a count from the counter to the system parameters, and modulating EAS transmission signals based on the comparison between the count and the system parameters. An EAS transmitter and an EAS system are also described.

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: The present disclosure includes a method and system for pipelining processes in an RF reader. In some implementations, a method includes receiving, from a transponder, a reply to an initial command. A physical (PHY) layer and a media control access (MAC) layer are pipelined to initiate transmission of a subsequent command during demodulation of the transponder reply.

Abstract: A method for controlling signal decay of a transmitted signal within a transmitter is described. The method includes measuring an amount of current induced back into the transmitter by the decaying signal, and using the current measurement to control the decay of the signal after the signal is transmitted from the load. A transmitter for an electronic article surveillance (EAS) system is also described which includes a current sensing circuit configured to at least sense an amount of current induced back into the transmitter by the load after transmission of the signal, and a transmitter control circuit configured to utilize the sensed current to determine an amount and a polarity of current to be applied to the load to reduce the induced current to a desired value.

Abstract: The present disclosure is directed to a system and method for interrogating radio frequency tags. In some implementations, a method includes A method includes successively polling, for a specified number of inventory cycles, a plurality of Radio Frequency Identification (RFID) tags in a first state. At least a first subset of the plurality of RFID tags transitions from the first state to a second state in response to the poll. After the specified number of inventory cycles, a command is transmitted to update at least a second subset of the plurality of RFID tags from the second state to first state. The plurality of RFID tags are subsequently polled after transmitting the update command.

Abstract: A method and system for synchronizing the operation of a plurality of electronic article surveillance (“EAS”) units that includes receiving a global positioning satellite reference signal, generating a synchronization master signal using the global positioning satellite reference signal and transmitting the master synchronization signal to the plurality of EAS units. The method and system can further include a secondary synchronization master, which is configurable to relay the master synchronization signal.

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: A system and method for providing wireless synchronized operation of electronic article surveillance (EAS) systems are provided. The method may include communicating wirelessly between each of a plurality of controllers connected to a plurality of detectors of the plurality of EAS systems and receiving with a communications receiver of each of the controllers wireless communications from at least some of the other plurality of controllers. The communications receiver may be separate from a tag detection receiver.

Abstract: A method for controlling operation of a transmitter in an electronic article surveillance (EAS) system is described that includes coupling each of a plurality of transmit channels to a corresponding antenna, configuring a modulator within each transmit channel to output a modulated signal to the corresponding antenna, providing feedback of each modulated signal, and adjusting operation of each modulator based on the feedback. An EAS transmitter and an EAS system are also described.

Abstract: A distributed wireless phase locked loop system for synchronizing the transmit carrier's modulating waveform, such as the transmitter pulse timing in a pulsed EAS system and the transmit sweeping function for swept RF synchronization, is provided. To remove the effect of phase noise on the power line signal, a phase locked loop is used to filter this signal. The filtered output is used as a reference to a second phase locked loop tied to a numerically controlled oscillator and the received signal to provide a distributed phase looked loop algorithm that is wireless, and automatically synchronizes adjacent EAS systems.

Abstract: A ringdown canceller is provided for electronic article surveillance (EAS) tag response processing, which uses two adaptive replica signals and compares the replica signal phase to the receive signal phase to determine if there is a stationary EAS tag in the interrogation or detection zone. The adaptive replica buffers allow the system to adjust to changing ambient conditions, and adjust rapidly to an EAS tag that suddenly appears in the detection zone and becomes stationary, or to a stationary EAS tag that suddenly leaves the detection zone. The ringdown response of the transmitter circuit is constant, just like a stationary tag, and is removed from the receive signal in the same manner as a stationary tag.