Abstract: Methods, systems, and apparatus, for calibration quality control using multiple magnetometers. One of the methods includes: receiving measurements by two or more magnetic field sensors of a device over a period of time, wherein each measurement measures a magnetic field at each magnetic field sensor, wherein each measurement at each time point over the period of time includes a vector in one or more spatial axes of a three-dimensional space; computing a difference between the measurements over the period of time, wherein the difference at each time point over the period of time is a result of computing a difference based on one or more pairs of the vectors at the time point; determining that the difference does not remain within a predetermined range over the period of time; and in response, classifying calibration quality of the device as unsuitable for computing a heading of the device.

Abstract: The present disclosure provides for using multiple inertial measurement units (IMUs) to recognize particular user activity, such as particular types of exercises and repetitions of such exercises. The IMUs may be located in consumer products, such as smartwatches and earbuds. Each IMU may include an accelerometer and a gyroscope, each with three axes of measurement, for a total of 12 raw measurement streams. A training image includes a plurality of subplots or tiles, each depicting a separate data stream. The training image is then used to train a machine learning model to recognize IMU data as corresponding to a particular type of exercise.

Abstract: The present disclosure provides for using multiple inertial measurement units (IMUs) to recognize particular user activity, such as particular types of exercises and repetitions of such exercises. The IMUs may be located in consumer products, such as smartwatches and earbuds. Each IMU may include an accelerometer and a gyroscope, each with three axes of measurement, for a total of 12 raw measurement streams. A training image includes a plurality of subplots or tiles, each depicting a separate data stream. The training image is then used to train a machine learning model to recognize IMU data as corresponding to a particular type of exercise.

Abstract: The present disclosure provides for using multiple inertial measurement units (IMUs) to recognize particular user activity, such as particular types of exercises and repetitions of such exercises. The IMUs may be located in consumer products, such as smartwatches and earbuds. Each IMU may include an accelerometer and a gyroscope, each with three axes of measurement, for a total of 12 raw measurement streams. A training image includes a plurality of subplots or tiles, each depicting a separate data stream. The training image is then used to train a machine learning model to recognize IMU data as corresponding to a particular type of exercise.

Abstract: The present disclosure provides for using multiple inertial measurement units (IMUs) to recognize particular user activity, such as particular types of exercises and repetitions of such exercises. The IMUs may be located in consumer products, such as smartwatches and earbuds. Each IMU may include an accelerometer and a gyroscope, each with three axes of measurement, for a total of 12 raw measurement streams. A training image includes a plurality of subplots or tiles, each depicting a separate data stream. The training image is then used to train a machine learning model to recognize IMU data as corresponding to a particular type of exercise.

Abstract: A time domain switching analog-to-digital converter apparatus and methods of utilizing the same. In one implementation, the converter apparatus comprises a carrier signal source, and at least one reference source. The carrier signal is summed with the input signal and the summed modulated signal is fed to a comparator circuit. The comparator is configured detects crossings of the reference level by the modulated waveform thereby generating trigger events. The time period between consecutive trigger events is used to obtain modulated signal deviation due to the input signal thus enabling input signal measurement. Control of the carrier oscillation amplitude and frequency enables real time adjustment of the converter dynamic range and resolution. The use of additional reference signal levels increases sensor frequency response and accuracy. A dual channel converter apparatus enables estimation and removal of common mode noise, thereby improving signal conversion accuracy.

Abstract: A time domain switching analog-to-digital converter apparatus and methods of utilizing the same. In one implementation, the converter apparatus comprises a carrier signal source, and at least one reference source. The carrier signal is summed with the input signal and the summed modulated signal is fed to a comparator circuit. The comparator is configured detects crossings of the reference level by the modulated waveform thereby generating trigger events. The time period between consecutive trigger events is used to obtain modulated signal deviation due to the input signal thus enabling input signal measurement. Control of the carrier oscillation amplitude and frequency enables real time adjustment of the converter dynamic range and resolution. The use of additional reference signal levels increases sensor frequency response and accuracy. A dual channel converter apparatus enables estimation and removal of common mode noise, thereby improving signal conversion accuracy.

Abstract: A geophone including a plurality of ferromagnetic masses (e.g., magnets) disposed to oscillate on one or more compliant elements (e.g., springs) in a manner that produces a steep flux gradient at one or more conductive coils is disclosed. The magnetic masses are positioned with like poles facing each other so as to compress the magnetic field gradient. The coils may be positioned in the flux gap either between the magnets, in close proximity to the magnets, or surrounding the magnets. Vibration measurements may then be detected from the movement of at least one of the magnetic masses.

Abstract: A method for analyzing an optical signal comprising: directing the optical signal into a scanning spectrometer system comprising a variable-wavelength filter and a detector; continuously modulating the variable-wavelength filter at a given modulation frequency to produce a time-based waveform; measuring the time-based waveform with the detector; converting the time-based waveform into a frequency spectrum comprising harmonics of the modulation frequency; and comparing the harmonics of the modulation frequency to premeasured harmonic spectra in a reference database.

Abstract: An energy harvester comprising: a substrate; two magnets coupled to the substrate in close proximity to each other with like magnetic poles facing each other creating a flux gap; a coil coupled to the substrate and disposed within the flux gap, wherein the coil and the magnets are coupled to the substrate such that substrate acceleration causes relative elastic motion between the magnets and the coil thereby exposing the coil to a changing magnetic flux; and a resonant frequency tuner coupled to the substrate and configured to adjust the resonant frequency between the coil and the magnets.

Abstract: An energy harvesting apparatus comprising: a substrate; two magnets coupled to the substrate in close proximity to each other with like magnetic poles facing each other creating a flux gap; a coil coupled to the substrate and disposed within the flux gap, wherein the coil and the magnets are coupled to the substrate such that substrate acceleration causes relative motion between the magnets and the coil thereby exposing the coil to a changing magnetic flux.

Abstract: A geophone including a plurality of ferromagnetic masses (e.g., magnets) disposed to oscillate on one or more compliant elements (e.g., springs) in a manner that produces a steep flux gradient at one or more conductive coils is disclosed. The magnetic masses are positioned with like poles facing each other so as to compress the magnetic field gradient. The coils may be positioned in the flux gap either between the magnets, in close proximity to the magnets, or surrounding the magnets. Vibration measurements may then be detected from the movement of at least one of the magnetic masses.