Abstract: A gateway includes memory configured to store computer-readable program code; and processing circuitry configured to access the memory and execute the computer-readable program code. The gateway is connected or connectable to a low-power wide area (LPWA) network. The gateway is caused to transmit a common timing reference at a constant interval that delineates an epoch including timeslots assignable to network nodes and a free-for-all interval. The gateway is also caused to join a network node to the LPWA network based on the common timing reference and is further caused to receive a join message including a measure of received signal strength or quality of the common timing reference at the network node. The gateway is also caused to assign one or more timeslots within the epoch, a frequency, a channel, or a modulation to the network node based on the measure of received signal strength or other quality.

Abstract: A gateway includes memory configured to store computer-readable program code; and processing circuitry configured to access the memory and execute the computer-readable program code. The gateway is connected or connectable to a low-power wide area (LPWA) network. The gateway is caused to transmit a common timing reference at a constant interval that delineates an epoch including timeslots assignable to network nodes and a free-for-all interval. The gateway is also caused to join a network node to the LPWA network based on the common timing reference and is further caused to receive a join message including a measure of received signal strength or quality of the common timing reference at the network node. The gateway is also caused to assign one or more timeslots within the epoch, a frequency, a channel, or a modulation to the network node based on the measure of received signal strength or other quality.

Abstract: A method for controlling a magnetostrictive ultrasonic transducer of the type used in a magnetostrictive ultrasonic dental scaler includes generating a drive signal for a resonant circuit using a full bridge synchronous class D amplifier. The electrical signal output by the resonant circuit drives an excitation coil that generates an electromagnetic field that causes the magnetostrictive ultrasonic transducer to vibrate. A feedback wire is rendered unnecessary by measuring current and voltage outputs of the resonant circuit and quadrature sampling the measured current and voltage outputs at the same sampling rate as used for the generation of the electrical signal by the resonant circuit. A pulse width modulated signal is generated from the quadrature sampled sensed current and voltage that represents a pulse train approximation of a sine wave of the drive signal for, in turn, being applied to the full bridge synchronous class D amplifier to generate the drive signal for the resonant circuit.

Abstract: A method for controlling a magnetostrictive ultrasonic transducer of the type used in a magnetostrictive ultrasonic dental scaler includes generating a drive signal for a resonant circuit using a full bridge synchronous class D amplifier. The electrical signal output by the resonant circuit drives an excitation coil that generates an electromagnetic field that causes the magnetostrictive ultrasonic transducer to vibrate. A feedback wire is rendered unnecessary by measuring current and voltage outputs of the resonant circuit and quadrature sampling the measured current and voltage outputs at the same sampling rate as used for the generation of the electrical signal by the resonant circuit. A pulse width modulated signal is generated from the quadrature sampled sensed current and voltage that represents a pulse train approximation of a sine wave of the drive signal for, in turn, being applied to the full bridge synchronous class D amplifier to generate the drive signal for the resonant circuit.

Abstract: In one embodiment, an antenna configuration for locating RFID tags has two sets of (mutually orthogonal) elongated reader coils, where each elongated reader coil corresponds to two or more different possible locations of RFID tags, and each possible location is associated with one reader coil in each of the two sets. The identities and locations of RFID tags can be determined by (sequentially) energizing the different sets of reader coils and correlating the recorded responses from RFID tags. In one application, the antenna configuration is used at the box level of a cold storage system for biological samples having one or more freezers, each freezer having one or racks, each rack receiving one or more boxes, each box receiving one or more sample containers, where, in addition to the biological sample, each sample container has a unique passive RFID tag.

Abstract: A method for suppressing narrowband interference signals is provided. The method comprises inputting a digitized signal to a fast Fourier transform (FFT) to produce a plurality of contiguous frequency bins, examining said frequency bins to identify those bins containing narrowband interference above an excision threshold as excise bins, excising said excise bins to leave residual bins, implementing a lower resolution FFT analysis receiver to monitor broadband components and to mask out the narrowband interference excised in the excising step, reconstructing the signal with said residual bins using an inverse fast Fourier transform (IFFT), and outputting said reconstructed signal to a receiver as a protected signal having improved signal characteristics through reduced narrowband interference. The protected signal is used to produce enhanced operation in said receiver.

Abstract: In one embodiment, an antenna configuration for locating RFID tags has two sets of (mutually orthogonal) elongated reader coils, where each elongated reader coil corresponds to two or more different possible locations of RFID tags, and each possible location is associated with one reader coil in each of the two sets. The identities and locations of RFID tags can be determined by (sequentially) energizing the different sets of reader coils and correlating the recorded responses from RFID tags. In one application, the antenna configuration is used at the box level of a cold storage system for biological samples having one or more freezers, each freezer having one or racks, each rack receiving one or more boxes, each box receiving one or more sample containers, where, in addition to the biological sample, each sample container has a unique passive RFID tag.

Abstract: A method for suppressing narrowband interference signals is provided. The method comprises inputting a digitized signal to a fast Fourier transform (FFT) to produce a plurality of contiguous frequency bins, examining said frequency bins to identify those bins containing narrowband interference above an excision threshold as excise bins, excising said excise bins to leave residual bins, implementing a lower resolution FFT analysis receiver to monitor broadband components and to mask out the narrowband interference excised in the excising step, reconstructing the signal with said residual bins using an inverse fast Fourier transform (IFFT), and outputting said reconstructed signal to a receiver as a protected signal having improved signal characteristics through reduced narrowband interference. The protected signal is used to produce enhanced operation in said receiver.

Abstract: A narrowband interference excision and nulling system for Global Positioning Satellite (GPS), spread spectrum navigation and communication bands, and an antijam electronic apparatus that operates using RF conversion and digital signal processing. A band containing the signal of interest as well as interference is converted to an intermediate frequency (IF) for RF filtering using single conversion, and this signal is digitized using an analog-to-digital converter (ADC). A representation of the signal is produced at a lower frequency using digitization and filtering, and a continuous data representation of the band is processed using multiple-point samples to define the input to a complex FFT. The FFT produces contiguous frequency bins that are examined to identify narrowband and broadband interference.

Abstract: A narrowband interference excision and nulling system for Global Positioning Satellite (GPS), spread spectrum navigation and communication bands, and an antijam electronic apparatus that operates using RF conversion and digital signal processing. A band containing the signal of interest as well as interference is converted to an intermediate frequency (IF) for RF filtering using single conversion, and this signal is digitized using an analog-to-digital converter (ADC). A representation of the signal is produced at a lower frequency using digitization and filtering, and a continuous data representation of the band is processed using multiple-point samples to define the input to a complex FFT. The FFT produces contiguous frequency bins that are examined to identify narrowband and broadband interference.

Abstract: A perimeter monitoring system intended for the enhanced safety of children includes a receiver communicating with a plurality of transmitters worn by the monitored individuals within a predefined perimeter area surrounded by a perimeter loop antenna. A periodic transmission is sent by each transmitter to the receiver as confirmation that the child is presently within the desired area. The system will alarm the operator and provide an indication identifying any one of the monitored children that either leaves the predefined perimeter or enters a restricted area.

Abstract: A perimeter monitoring system intended for the enhanced safety of children includes a receiver communicating with a plurality of transmitters worn by the monitored individuals within a predefined perimeter area surrounded by a perimeter loop antenna. A periodic transmission is sent by each transmitter to the receiver as confirmation that the child is presently within the desired area. The system will alarm the operator and provide an indication identifying any one of the monitored children that either leaves the predefined perimeter or enters a restricted area.