Method and apparatus for signal decomposition, analysis, reconstruction and tracking
A system and method for representing quasi-periodic (“qp”) waveforms, for example, representing a plurality of limited decompositions of the qp 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 qp waveform. Data-structure attributes are created and used to reconstruct the qp waveform. Features of the qp wave are tracked using pattern-ecognition 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.
1. An apparatus comprising:
a computer system having a storage device;
a source of an initial series of digitized signal values;
a first plurality of digital-bandpass filters each operably coupled to the source of digitized signal values and each configured to digitally filter the initial series of digitized signal values, wherein each one of the first plurality of digital-bandpass filters has a respective center frequency that is unique among respective center frequencies of the first plurality of digital-bandpass filters and a respective frequency range that overlaps the respective frequency range of a closest neighboring one of the first plurality of digital-bandpass filters, and wherein each one of the first plurality of digital-bandpass filters has an output signal;
a first plurality of quarter-phase measurement units implemented by software and circuitry in the computer system that each determines a plurality of amplitude values and at least four phase-determined time points per full waveform cycle of the output signal of a corresponding one of the first plurality of digital bandpass filters; and
a first frequency-component tracker implemented by software and circuitry in the computer system that uses the output signals from the plurality of quarter-phase measurement units to detect and track a first frequency component as that first tracked frequency component changes from being primarily within the respective frequency range of a first one of the first plurality of digital-bandpass filters to being primarily within the respective frequency range of a second one of the first plurality of digital-bandpass filters.
2. The apparatus of claim 1 , wherein each one of the first plurality of digital-bandpass filters includes a wavelet-transform filter.
3. The apparatus of claim 1 , wherein the first frequency-component tracker further includes:
an output quarter-phase measurement unit that determines at least two amplitude values and at least four phase-determined time points per full waveform cycle of the first tracked frequency component, and that outputs a first series of respective data structures that each indicates the at least two amplitude values, the at least four phase-determined time points per respective full waveform cycle of the first tracked frequency component, and a per-cycle instantaneous frequency of the first tracked frequency component for the respective full waveform cycle of the first tracked frequency component.
4. The apparatus of claim 1 ,
wherein each one of the first plurality of digital-bandpass filters is a wavelet-transform filter; and
wherein the first frequency-component tracker further includes:
a first quarter-phase maximum-amplitude determination unit that determines which one of the first plurality of quarter-phase measurement units had a maximum amplitude value with a magnitude no smaller than did any other one of the first plurality of quarter-phase measurement units during a time period and that outputs a selection signal based on the determination; and
a first selector that selects information from at least one of first plurality of quarter-phase measurement units based on the selection signal, and outputs the selected information and an indication of frequency from the corresponding at least one of the first plurality of digital-bandpass filters.
5. The apparatus of claim 1 , further comprising:
a second plurality of digital-bandpass filters, wherein each one of the second plurality of digital-bandpass filters has a center frequency that is unique among the second plurality of digital-bandpass filters, wherein each one of the second plurality of digital-bandpass filters is a wavelet-transform filter, and wherein each one of the second plurality of digital-bandpass filters has an output signal;
a second plurality of quarter-phase measurement units operatively coupled to receive the output signals from the second plurality of digital-bandpass filters, wherein each of the second plurality of quarter-phase measurement units determines and outputs at least two amplitude values and at least four phase-determined time points per full waveform cycle of a corresponding one of the second plurality of digital-bandpass filters;
wherein each one of the first plurality of digital-bandpass filters is a wavelet-transform filter; and
wherein the first frequency-component tracker further includes:
a quarter-phase maximum-amplitude determination unit that determines which one of the first plurality of quarter-phase measurement units had a maximum amplitude value with a magnitude no smaller than did any other one of the first plurality of quarter-phase measurement units during a time period and that outputs a selection signal based on the determination; and
a selector that selects information from at least one of second plurality of quarter-phase measurement units based on the selection signal, and outputs the selected information and an indication of a frequency of the first tracked frequency component.
6. The apparatus of claim 1 , wherein the first frequency-component tracker outputs a series of data structures each containing a quarter-phase label (Lqp), an interpolated quarter-phase index value (iqp), and an interpolated quarter-phase amplitude value (aqp) of the tracked frequency component.
7. The apparatus of claim 1 , wherein the first plurality of quarter-phase measurement units each further includes:
an interpolator that interpolates a quarter-phase index value (iqp) and a quarter-phase amplitude value (aqp) at QP points of the output signal of the corresponding one of the first plurality of digital bandpass filters.
8. A computer-implemented method comprising:
digitally filtering an initial series of digitized signal values in a computer system to generate a first plurality of digitally bandpass filtered signals, wherein each one of the first plurality of digitally bandpass filtered signals has a respective center frequency that is unique among respective center frequencies of the first plurality of digitally bandpass filtered signals and a respective frequency range that overlaps the respective frequency range of a closest neighboring one of the first plurality of digitally bandpass filtered signals;
determining, with software and circuitry in the computer system, a first plurality of quarter-phase amplitude values and quarter-phase-determined time points per full waveform cycle of each one of the first plurality of digitally bandpass filtered signals;
using the first plurality of quarter-phase amplitude values for detecting and tracking, with software and circuitry in the computer system, a first tracked frequency component as that first tracked frequency component changes from being primarily within the respective frequency range of a first one of the first plurality of digitally bandpass filtered signals to being primarily within the respective frequency range of a second one of the first plurality of digitally bandpass filtered signals; and
storing information regarding the tracked frequency component into a storage device.
9. The computer-implemented method of claim 8 , wherein the digitally filtering of the initial series of digitized signal values to generate the first plurality of digitally bandpass filtered signals further includes filtering the initial series of digitized signal values to generate a plurality of wavelet-transformed signals, based on a wavelet from a wavelet transform.
10. The computer-implemented method of claim 8 , wherein the using of the first plurality of quarter-phase amplitude values for detecting and tracking the first frequency component further includes:
determining at least two amplitude values and at least four phase-determined time points per full waveform cycle of the first tracked frequency component, and
outputting a first series of respective data structures that each indicates the at least two amplitude values, the at least four phase-determined time points per respective full waveform cycle of the first tracked frequency component, and a per-cycle frequency of the first tracked frequency component for the respective full waveform cycle of the first tracked frequency component.
11. The computer-implemented method of claim 8 ,
wherein the digitally filtering to generate the first plurality of digitally bandpass filtered signals includes filtering the initial series of digitized signal values to generate a plurality of wavelet-transformed signals, based on a wavelet from a wavelet transform, and
wherein the using of the first plurality of quarter-phase amplitude values for detecting and tracking the first tracked frequency component further includes:
determining which one of the first plurality of quarter-phase measurement units had a maximum amplitude value with a magnitude no smaller than did any other one of the first plurality of quarter-phase measurement units during a time period and that outputs a selection signal based on the determination; and
selecting information from at least one of first plurality of quarter-phase amplitude values and the first plurality of quarter-phase-determined time points based on the selection signal, and outputting the selected information and an indication of frequency from the corresponding at least one of the first plurality of digitally bandpass filtered signals.
12. The computer-implemented method of claim 8 , further comprising:
digitally filtering the initial series of digitized signal values in a computer to generate a second plurality of digitally wavelet-transformed signals based on a wavelet from a wavelet transform, wherein each one of the second plurality of digitally bandpass filtered signals has a respective center frequency that is unique among respective center frequencies of the second plurality of digitally bandpass filtered signals and a respective frequency range that overlaps the respective frequency range of a closest neighboring one of the second plurality of digitally bandpass filtered signals;
determining a second plurality of quarter-phase amplitude values and quarter-phase-determined time points per full waveform cycle of each corresponding one of the second plurality of digitally bandpass filtered signals;
wherein the digitally filtering to generate the first plurality of digitally bandpass filtered signals includes filtering the initial series of digitized signal values to generate a plurality of wavelet-transformed signals based on a wavelet from a wavelet transform, and
wherein the using of the first plurality of quarter-phase amplitude values for detecting and tracking the first tracked frequency component further includes:
determining which one of the first plurality of quarter-phase amplitude values and quarter-phase-determined time points had a maximum amplitude value with a magnitude no smaller than did any other one of the first plurality of quarter-phase amplitude values and quarter-phase-determined time points during a time period and outputting a selection signal based on the determination; and
selecting information from at least one of second plurality of quarter-phase amplitude values and quarter-phase-determined time points based on the selection signal, and outputting the selected information and an indication of frequency from the corresponding at least one of the second plurality of digitally bandpass filtered signals.
13. The computer-implemented method of claim 8 , further comprising:
outputting a series of data structures each containing a quarter-phase label (Lqp), an interpolated quarter-phase index value (iqp), and an interpolated quarter-phase amplitude value (aqp) of the tracked frequency component.
14. The computer-implemented method of claim 8 , further comprising:
interpolating a quarter-phase index value (iqp) and a quarter-phase amplitude value (aqp) at QP points of a corresponding one of the first plurality of digitally bandpass filtered signals.
15. A non-transitory computer-readable storage medium having instructions stored thereon, wherein the instructions, when executed by a suitably programmed computer system, perform a method comprising:
digitally filtering an initial series of digitized signal values in the computer system to generate a first plurality of digitally bandpass filtered signals, wherein each one of the first plurality of digitally bandpass filtered signals has a respective center frequency that is unique among respective center frequencies of the first plurality of digitally bandpass filtered signals and a respective frequency range that overlaps the respective frequency range of a closest neighboring one of the first plurality of digitally bandpass filtered signals;
determining, with software and circuitry in the computer system, a first plurality of quarter-phase amplitude values and quarter-phase-determined time points per full waveform cycle of each one of the first plurality of digitally bandpass filtered signals;
using the first plurality of quarter-phase amplitude values for detecting and tracking, with software and circuitry in the computer system, a first tracked frequency component as that first tracked frequency component changes from being primarily within the respective frequency range of a first one of the first plurality of digitally bandpass filtered signals to being primarily within the respective frequency range of a second one of the first plurality of digitally bandpass filtered signals; and
storing information regarding the tracked frequency component into a storage device.
16. The computer-readable storage medium of claim 15 , having further instructions stored thereon, wherein the further instructions, when executed by a suitably programmed computer, cause the digitally filtering of the initial series of digitized signal values to generate the first plurality of digitally bandpass filtered signals to further include filtering the initial series of digitized signal values to generate a plurality of wavelet-transformed signals, based on a wavelet from a wavelet transform.
17. The computer-readable storage medium of claim 15 , having further instructions stored thereon, wherein the further instructions, when executed by a suitably programmed computer, cause the using of the first plurality of quarter-phase amplitude values for detecting and tracking the first frequency component to further include:
determining at least two amplitude values and at least four phase-determined time points per full waveform cycle of the first tracked frequency component, and
outputting a first series of respective data structures that each indicates the at least two amplitude values, the at least four phase-determined time points per respective full waveform cycle of the first tracked frequency component, and a per-cycle frequency of the first tracked frequency component for the respective full waveform cycle of the first tracked frequency component.
18. The computer-readable storage medium of claim 15 , having further instructions stored thereon, wherein the further instructions, when executed by a suitably programmed computer, cause the digitally filtering to generate the first plurality of digitally bandpass filtered signals to further include filtering the initial series of digitized signal values to generate a plurality of wavelet-transformed signals, based on a wavelet from a wavelet transform, and
wherein the using of the first plurality of quarter-phase amplitude values for detecting and tracking the first tracked frequency component further includes:
determining which one of the first plurality of quarter-phase measurement units had a maximum amplitude value with a magnitude no smaller than did any other one of the first plurality of quarter-phase measurement units during a time period and that outputs a selection signal based on the determination; and
selecting information from at least one of first plurality of quarter-phase amplitude values and the first plurality of quarter-phase-determined time points based on the selection signal, and outputting the selected information and an indication of frequency from the corresponding at least one of the first plurality of digitally bandpass filtered signals.
19. The computer-readable storage medium of claim 15 , having further instructions stored thereon, wherein the further instructions, when executed by a suitably programmed computer, cause the method to further include:
digitally filtering the initial series of digitized signal values in a computer to generate a second plurality of digitally wavelet-transformed signals based on a wavelet from a wavelet transform, wherein each one of the second plurality of digitally bandpass filtered signals has a respective center frequency that is unique among respective center frequencies of the second plurality of digitally bandpass filtered signals and a respective frequency range that overlaps the respective frequency range of a closest neighboring one of the second plurality of digitally bandpass filtered signals;
determining a second plurality of quarter-phase amplitude values and quarter-phase-determined time points per full waveform cycle of each corresponding one of the second plurality of digitally bandpass filtered signals;
wherein the digitally filtering to generate the first plurality of digitally bandpass filtered signals includes filtering the initial series of digitized signal values to generate a plurality of wavelet-transformed signals based on a wavelet from a wavelet transform, and
wherein the using of the first plurality of quarter-phase amplitude values for detecting and tracking the first tracked frequency component further includes:
determining which one of the first plurality of quarter-phase amplitude values and quarter-phase-determined time points had a maximum amplitude value with a magnitude no smaller than did any other one of the first plurality of quarter-phase amplitude values and quarter-phase-determined time points during a time period and outputting a selection signal based on the determination; and
selecting information from at least one of second plurality of quarter-phase amplitude values and quarter-phase-determined time points based on the selection signal, and outputting the selected information and an indication of frequency from the corresponding at least one of the second plurality of digitally bandpass filtered signals.
20. The computer-readable storage medium of claim 15 , having further instructions stored thereon, wherein the further instructions, when executed by a suitably programmed computer, cause the method to further include:
outputting a series of data structures each containing
a quarter-phase label (Lqp),
an interpolated quarter-phase index value (iqp), and
an interpolated quarter-phase amplitude value (aqp) of the tracked frequency component.