Abstract: Ultrasonic audio processing circuitry and a method useful in ultrasonic presence detection. An ultrasonic burst generator produces an ultrasonic burst signal at one or more ultrasonic frequencies, and an equalizer equalizes that ultrasonic burst signal according to frequency response characteristics of the speaker and microphone at those ultrasonic frequencies. Driver circuitry drives a speaker with the ultrasonic burst signal, which may be combined with an audible audio signal. An ultrasonic separation filter separates an ultrasonic portion from a signal received at a microphone, and processing circuitry is provided to determine a delay time of an echo corresponding to the ultrasonic burst signal in that separated ultrasonic portion of the received signal. In another aspect, the equalizer equalizes an ultrasonic portion of the signal received at a microphone, according to frequency response characteristics of the speaker and microphone at the ultrasonic frequencies of the burst.

Abstract: In a described example, a circuit includes a sensor circuit including multiple magnetic field sensors having respective sensor outputs. The magnetic field sensors are configured to provide magnetic field sensor signals at the respective sensor outputs representative of a measure of current flow through a conductive structure. A combiner interface has combiner inputs and a combiner output. The combiner inputs are coupled to the respective sensor outputs. The combiner interface is configured to provide an aggregate sensor measurement at the combiner output responsive to the magnetic field sensor signals, in which the aggregate sensor measurement is decoupled from magnetic fields generated responsive to the current flow through the conductive structure.

Abstract: In an ultrasonic detection system that uses frequency-modulation or phase-modulation coding to distinguish emitted bursts from multiple transducers, a receiver associated with a transducer uses peak search, peak buffer, and peak rank stages in one or more receiver signal processing paths to identify valid received ultrasonic signal envelope peaks in correlator outputs. The peak rank stage can support different modes respectively designed to handle one code, two or more codes, or two or more codes with support for Doppler frequency shift detection. Valid peak information (e.g., amplitude and time) can be reported to a central controller and/or stored locally in a fusion stage to generate more intelligent information for targets or obstacles using peaks from multiple bursts.

Abstract: In an ultrasonic detection system that uses frequency-modulation coding to distinguish emitted bursts from multiple transducers, a receiver associated with a transducer uses dynamic thresholding to discriminate valid echoes from system and environmental noise in multiple envelope signals produced by multiple correlators. The time-varying dynamic thresholds are generated from the mean of noise in a respective envelope derived from the output of a respective correlator. Multiple thresholds can be combined together such that a single time-varying threshold is applied to all correlators' envelopes. Such thresholding has the benefits of a constant false-alarm rate with regard to detection of echoes (as opposed to false triggering from noise), and, owing to finer-resolution and adaptive thresholds, can detect targets or obstacles as further distances and with greater time responsiveness.

Abstract: A sensor chip includes a sensor pixel. The sensor pixel includes an avalanche photodetector. A circuit is adjacent to the avalanche photodetector. The circuit is coupled to the avalanche photodetector. An isolation structure at least partially encloses the circuit and is between the avalanche photodetector and the circuit.

Abstract: Current sensing techniques. In an example, a current sensing method includes: generating a first magnetic field measurement; generating a second magnetic field measurement; generating a frequency estimate of a current; calculating a root-mean-square (RMS) value of an estimated amplitude of the current; and generating a temperature estimate of an integrated circuit (IC) configured to perform the method. The method also includes generating a first weighting factor and a second weighting factor based on the frequency estimate, the RMS value, and the temperature estimate, the first weighting factor to control amplification of the first magnetic field measurement and the second weighting factor to control amplification of the second magnetic field measurement.

Abstract: Ultrasonic audio processing circuitry and a method useful in ultrasonic presence detection. An ultrasonic burst generator produces an ultrasonic burst signal at one or more ultrasonic frequencies, and an equalizer equalizes that ultrasonic burst signal according to frequency response characteristics of the speaker and microphone at those ultrasonic frequencies. Driver circuitry drives a speaker with the ultrasonic burst signal, which may be combined with an audible audio signal. An ultrasonic separation filter separates an ultrasonic portion from a signal received at a microphone, and processing circuitry is provided to determine a delay time of an echo corresponding to the ultrasonic burst signal in that separated ultrasonic portion of the received signal. In another aspect, the equalizer equalizes an ultrasonic portion of the signal received at a microphone, according to frequency response characteristics of the speaker and microphone at the ultrasonic frequencies of the burst.

Abstract: An ultrasound detect circuit includes a decimator that decimates a transmit signal to be transmitted through an ultrasonic transducer. The transmit signal is decimated to generate first and second template signals. The decimator uses a different decimation ratio to generate the first template signal than the second template signal. The circuit also includes a first correlator to correlate a signal derived from the ultrasonic transducer with the first template signal, aa second correlator to correlate the signal derived from the ultrasonic transducer with the second template signal, and a Doppler shift determination circuit to determine a Doppler frequency shift based on an output from the first correlator and an output from the second correlator.

Abstract: Ultrasonic sensing systems and associated methods provide side-lobe reduction to improve the acoustic detection of small objects, the signature envelope peaks of which can otherwise be obscured by subsidiary envelope peaks in side lobes that result from residual correlation between a signal received by an ultrasonic transducer and a template signal corresponding to a burst signal emitted by the ultrasonic transducer. A shaping signal by which the amplitude of the burst signal can be varied with respect to time is taken into account in the template signal, and correlator circuitry correlates a signal derived from the ultrasonic transducer with the template signal to produce a correlated output exhibiting the desired side-lobe reduction. The distance from the transducer to the detected object can thereby be determined with enhanced accuracy and responsiveness.

Abstract: In a described example, a circuit includes a sensor circuit including multiple magnetic field sensors having respective sensor outputs. The magnetic field sensors are configured to provide magnetic field sensor signals at the respective sensor outputs representative of a measure of current flow through a conductive structure. A combiner interface has combiner inputs and a combiner output. The combiner inputs are coupled to the respective sensor outputs. The combiner interface is configured to provide an aggregate sensor measurement at the combiner output responsive to the magnetic field sensor signals, in which the aggregate sensor measurement is decoupled from magnetic fields generated responsive to the current flow through the conductive structure.

Abstract: Ultrasonic ranging systems and methods that emit coded bursts and correlate transduced acoustical echoes of the bursts with a receive template characterizing a burst code to determine time-of-flight information use receive templates of time-variable length to improve short-range object detection. The template length is based on a time index measured from the start of the burst emission. The detection can account for a dead zone of transducer ringing following a burst. A time-variable gain that is also based on the time index can be applied to the correlated signal. The length and gain can be adjusted with reduced temporal frequency to reduce computation cost.

Abstract: Ultrasonic ranging systems and methods that emit coded bursts and correlate transduced acoustical echoes of the bursts with a receive template characterizing a burst code to determine time-of-flight information use receive templates of time-variable length to improve short-range object detection. The template length is based on a time index measured from the start of the burst emission. The detection can account for a dead zone of transducer ringing following a burst. A time-variable gain that is also based on the time index can be applied to the correlated signal. The length and gain can be adjusted with reduced temporal frequency to reduce computation cost.

Abstract: An ultrasonic sensing system includes: an amplifier including an input and an output; and an n-level comparator, coupled to the output of the amplifier, to compare an adjustable threshold voltage to an output signal from the output of the amplifier. N is greater than or equal to 1. The system also includes a noise power estimator, coupled to an output of the n-level comparator, to generate a noise power signal indicative of noise power of an input signal at the input of the amplifier. The system further includes a time-varying threshold circuit, coupled to the noise power estimator and the n-level comparator, to adjust the adjustable threshold voltage based on the noise power signal.

Abstract: Ultrasonic ranging systems and methods that emit coded bursts and correlate transduced acoustical echoes of the bursts with a receive template characterizing a burst code to determine time-of-flight information use receive templates of time-variable length to improve short-range object detection. The template length is based on a time index measured from the start of the burst emission. The detection can account for a dead zone of transducer ringing following a burst. A time-variable gain that is also based on the time index can be applied to the correlated signal. The length and gain can be adjusted with reduced temporal frequency to reduce computation cost.

Abstract: Ultrasonic sensing systems and associated methods provide side-lobe reduction to improve the acoustic detection of small objects, the signature envelope peaks of which can otherwise be obscured by subsidiary envelope peaks in side lobes that result from residual correlation between a signal received by an ultrasonic transducer and a template signal corresponding to a burst signal emitted by the ultrasonic transducer. A shaping signal by which the amplitude of the burst signal can be varied with respect to time is taken into account in the template signal, and correlator circuitry correlates a signal derived from the ultrasonic transducer with the template signal to produce a correlated output exhibiting the desired side-lobe reduction. The distance from the transducer to the detected object can thereby be determined with enhanced accuracy and responsiveness.

Abstract: Ultrasonic ranging systems and methods that use coding to distinguish emitted bursts from multiple transducers temporally stagger the bursts emitted from the transducers. The stagger delay between bursts from different transducers in a sensing frame can be randomized between different sensing frames to prevent blind zones. The stagger delay can be relatively small (e.g., between 3 ms and 10 ms) as compared to delays required between bursts in a single-tone ranging system (which would need to be more on the order of between 30 ms and 40 ms, depending on the maximum detecting range of the ranging system). The coding of bursts can be selected to utilize the entire bandwidth of the bursting transducer so as to preserve short-range sensitivity over transducer ringing. Schemes in which some transducers in a system only listen for bursts from other transducers but do not themselves burst within a sensing frame are also described.

Abstract: An ultrasound detect circuit includes a decimator that decimates a transmit signal to be transmitted through an ultrasonic transducer. The transmit signal is decimated to generate first and second template signals. The decimator uses a different decimation ratio to generate the first template signal than the second template signal. The circuit also includes a first correlator to correlate a signal derived from the ultrasonic transducer with the first template signal, aa second correlator to correlate the signal derived from the ultrasonic transducer with the second template signal, and a Doppler shift determination circuit to determine a Doppler frequency shift based on an output from the first correlator and an output from the second correlator.

Abstract: A computer-readable storage device stores machine instructions which, when executed by one or more central processing unit (CPU) cores, causes the one or more CPU cores to use a first ultrasonic transducer and a second ultrasonic transducer to measure fluid flow using a current measurement frequency and to perform a temperature calibration process. The temperature calibration process includes the sequentially generation of a plurality of electrical signals for the first ultrasonic transducer, the generated electrical signals each having a different frequency. For each frequency, the temperature calibration process includes the measurement of an amplitude of a signal from the second ultrasonic transducer. Based on the measured amplitudes of the signals from the second ultrasonic transducer, the temperature calibration process includes the determination of a new measurement frequency. The first and second ultrasonic transducers are used to measure fluid flow using the new measurement frequency.

Abstract: An optical position sensing system is disclosed. The system includes a substrate having a surface. A plurality of photodetectors are at multiple locations across the surface, each of the plurality of photodetectors providing detector pulse signals in response to receiving the light. The system further includes a processor that determines a phase shift between the transmitted light pulse signals and the respective detector pulse signals and applies a multi-path resolution operation to distinguish between the detector pulse signals representing the transmitted light pulse signals and those representing reflected light pulse signals. The processor also calculates a distance of a transmitting device from each of the photodetectors based on the determined phase shift and the multi-path resolution operation and calculates a multi-dimensional position of the transmitting device relative to the substrate based on the calculated distances.

Abstract: Methods and apparatus to determine nearfield localization using phase and received signal strength indication (RSSI) diversity are disclosed. An example method includes determining a first strength of an electric field and a second strength of a magnetic field, the electric field and the magnetic field associated with an electromagnetic signal sent from a transmitter; determining a difference between the first strength and the second strength; and determining a transmitter distance based on the difference between the first strength and the second strength.