Method and system for signal decomposition, analysis and reconstruction
Inventors
Ricci, Carlos A. • Kovtun, Vladimir V.
Assignees
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Publication Number
US-10367476-B2
Publication Date
2019-07-30
Expiration Date
Abstract
A system and method for representing quasi-periodic waveforms, for example, representing a plurality of limited decompositions of the quasi-periodic waveform. Each decomposition includes a first and second amplitude value and at least one time value. In some embodiments, each of the decompositions is phase adjusted such that the arithmetic sum of the plurality of limited decompositions reconstructs the quasi-periodic waveform. Data-structure attributes are created and used to reconstruct the quasi-periodic waveform. Features of the quasi-periodic wave are tracked using pattern-recognition techniques. The fundamental rate of the signal (e.g., heartbeat) can vary widely, for example by a factor of 2-3 or more from the lowest to highest frequency. To get quarter-phase representations of a component (e.g., lowest frequency “rate” component) that varies over time (by a factor of two to three) many overlapping filters use bandpass and overlap parameters that allow tracking the component's frequency version on changing quarter-phase basis.
Core Innovation
The invention represents quasi-periodic waveforms by digitally filtering an initial series of digitized signal values with a first filter bank that includes sets of digital bandpass filters per octave. Each set has a respective center frequency that is unique among the center frequencies of all sets, and the frequency ranges overlap those of a closest neighboring set. The filter bank produces respective filter output signals, which are then processed to generate fractional phase representations for successive time periods.
A first fractional-phase-unit bank generates a respective fractional phase representation for each successive time period based on the fractional-phase-unit corresponding to each set of digital bandpass filters. From these fractional-phase representations, a state constructor constructs a plurality of successive states containing information derived from the fractional phase representations. In the disclosed implementations, the fractional-phase representations include one or more amplitude values and a plurality of phase-determined time points per full waveform cycle.
The disclosed approach tracks a moving frequency component despite large fundamental-rate variation by using closely spaced, overlapping band center frequencies. It selects a dominant band/QP output and estimates more accurate instantaneous frequency and amplitude via interpolation or curve-fitting over neighboring band amplitudes, producing instantaneous frequency indications and more precise amplitude values. Data structures constructed from the successive states link tracked component features for pattern recognition and reconstruction.
Claims Coverage
The provided claim set includes three independent claims. Across these independent claims, the coverage focuses on per-octave digital bandpass filter banks with uniquely centered overlapping ranges, fractional-phase representations with amplitude values and phase-determined time points per full waveform cycle, and outputting state information derived from those fractional-phase representations.
Quasi-periodic signal processing with per-octave unique-center filter bank and fractional-phase state construction
An apparatus comprising a source of an initial series of digitized signal values; a first filter bank with sets of digital bandpass filters per octave where each set has a respective center frequency unique among the center frequencies of all sets and produces respective filter output signals; a first fractional-phase-unit bank that generates a respective fractional phase representation for each successive time period; and a state constructor that constructs a plurality of successive states containing information derived from the respective fractional phase representations.
Computer-implemented method for fractional-phase data states from uniquely centered overlapping per-octave bandpass filtering
A computer-implemented method comprising sensing a quasi-periodic signal and generating an initial series of digitized signal values; digitally filtering the initial series to generate a first set of digitally bandpass-filtered signals per octave with uniquely centered center frequencies and overlapping frequency ranges with closest neighboring sets; determining a plurality of fractional phase representations including one or more amplitude values and a plurality of phase-determined time points per full waveform cycle; and outputting a first series of respective fractional-phase data states indicating the one or more amplitude values and the phase-determined time points.
Non-transitory computer-readable storage medium instructions for outputting fractional-phase data states from per-octave unique-center filtering
A non-transitory computer-readable storage medium having instructions stored thereon that, when executed by a suitably programmed computer, perform a method comprising digitally filtering an initial series of digitized signal values in a computer to generate a set of digitally bandpass-filtered signals per octave where each set has a respective center frequency unique among respective center frequencies of all sets and a respective frequency range that overlaps a closest neighboring set; determining a plurality of fractional phase representations including one or more amplitude values and a plurality of phase-determined time points per full waveform cycle; and outputting a first series of respective fractional-phase data states indicating the one or more amplitude values and the plurality of phase-determined time points.
Across the independent claims, the inventive concept is the combination of per-octave digital bandpass filtering with uniquely centered overlapping frequency ranges, generation of fractional phase representations containing amplitude values and phase-determined time points per full waveform cycle, and construction/output of fractional-phase data states derived from those representations.
Stated Advantages
Tracks a moving frequency component despite large fundamental-rate variation by using closely spaced, overlapping band center frequencies.
Enables reconstruction based on phase-adjusted decompositions whose arithmetic sum enables reconstruction.
Provides fractional-phase data states indicating amplitude values and phase-determined time points per full waveform cycle for the digitally bandpass-filtered signals.
Documented Applications
Physiological signals, including ECG/heartbeat, as part of analyzing a tracked frequency component.
Seismic signals for earthquake prediction.
Internet messages/human activity prediction by using a tracked frequency component to help predict a human activity.
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