Signal segmentation and analysis
The present invention provides a system and method for representing quasi-periodic (“qp”) waveforms comprising, representing a plurality of limited decompositions of the qp waveform, wherein 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. These decompositions are stored into a data structure having a plurality of attributes. Optionally, these attributes are used to reconstruct the qp waveform, or patterns or features of the qp wave can be determined by using various pattern-recognition techniques. Some embodiments provide a system that uses software, embedded hardware or firmware to carry out the above-described method. Some embodiments use a computer-readable medium to store the data structure and/or instructions to execute the method.
1. An apparatus comprising:
a computer having a storage unit;
a receiver operatively coupled to the computer and configured to obtain a digitized signal having a series of digital values of a quasi-periodic waveform and to store the series of digital values in the storage unit, wherein the quasi-periodic waveform includes a cardiac signal;
a state generator operative coupled to generate a series of states defined by phase relationships between a plurality of frequency components of the cardiac signal based on the stored series of digital values; and
an automatic segment generator configured to automatically output representations of segments of the cardiac signal based on the series of states.
2. The apparatus of claim 1 , wherein the automatic segment generator creates graphical representations of the segments of the cardiac signal.
3. The apparatus of claim 1 , wherein the automatic segment generator creates matrix-table representations of the segments of the cardiac signal.
4. A computer-implemented method comprising:
obtaining a digitized signal having a series of digital values of a quasi-periodic waveform, wherein the quasi-periodic waveform includes a cardiac signal;
generating a series of states defined by phase relationships between a plurality of frequency components of the cardiac signal based on the series of digital values; and
automatically generating and outputting representations of segments of the cardiac signal based on the series of states.
5. The computer-implemented method of claim 4 , wherein the generating of the series of states further includes:
frequency filtering the cardiac signal into a plurality of frequency bands of a plurality of different frequencies, wherein each one of the plurality of frequency bands corresponds to one of the plurality of frequency components;
generating a plurality of fractional phase representations, wherein each one of the plurality of fractional-phase representations corresponds to one of the plurality of frequency bands; and
determining the series of states based on a sequence of phases in the plurality of fractional-phase representations.
6. The computer-implemented method of claim 4 , wherein the automatically generating and outputting representations of segments of the cardiac signal includes creating graphical representations of the segments of the cardiac signal.
7. The computer-implemented method of claim 4 , wherein the automatically generating and outputting representations of the segments of the cardiac signal includes creating matrix-table representations of the segments of the cardiac signal.
8. The computer-implemented method of claim 4 , wherein the automatically generating and outputting representations of segments of the cardiac signal includes creating a composite representation of each respective segment of the cardiac signal in each cell of a matrix-table graphical representations of the segments of the cardiac signal.
9. The computer-implemented method of claim 4 , wherein the generating of the series of states includes generating a resolution of sixteen (16) states.
10. The computer-implemented method of claim 4 , wherein the generating of the series of states includes generating a resolution of sixty-four (64) states.
11. The computer-implemented method of claim 4 , wherein the generating of the series of states includes generating a resolution of two-hundred-and-fifty-six (256) states.
12. The computer-implemented method of claim 4 , wherein the generating of the series of states further includes:
frequency filtering the cardiac signal into a plurality of frequency bands of a plurality of different frequencies, wherein each one of the plurality of frequency bands corresponds to one of the plurality of frequency components;
generating a plurality of fractional phase representations, wherein each one of the plurality of fractional-phase representations corresponds to one of the plurality of frequency bands; and
determining the series of states based on a sequence of phases in the plurality of fractional-phase representations, wherein each of the plurality of fractional phase representations includes a plurality of fractional phases, and wherein each fractional phase is associated with a phase label and includes one or more values representing at least one of an abscissa and an ordinate for each of at least one local cycle of the cardiac signal.
13. The computer-implemented method of claim 4 , wherein the generating of the series of states further includes:
frequency filtering the cardiac signal into a plurality of frequency bands of a plurality of different frequencies, wherein each one of the plurality of frequency bands corresponds to one of the plurality of frequency components,
generating a plurality of fractional phase representations, wherein each one of the plurality of fractional-phase representations corresponds to one of the plurality of frequency bands, and
determining the series of states based on a sequence of phases in the plurality of fractional-phase representations;
and wherein the method further includes:
determining a phase-adjustment value for a respective one of the plurality of fractional-phase representations such that a linear combination of values derived from the respective fractional-phase representation with values derived from one or more other fractional-phase representations obtained from other frequency bands substantially reconstructs the quasi-periodic waveform.
14. The computer-implemented method of claim 4 , wherein the generating of the series of states further includes:
frequency filtering the cardiac signal into a plurality of frequency bands of a plurality of different frequencies, wherein each one of the plurality of frequency bands corresponds to one of the plurality of frequency components;
generating a plurality of fractional-phase representations, wherein each one of the plurality of fractional-phase representations corresponds to one of the plurality of frequency bands; and
determining the series of states based on a sequence of phases in the plurality of fractional-phase representations, wherein the series of digital values include complex numbers, and wherein each one of the plurality of fractional-phase representations is associated with an angular range of a complex argument of the cardiac signal.
15. The computer-implemented method of claim 4 , wherein the automatically generating and outputting of the representations of segments of the cardiac signal includes graphically presenting the cardiac signal with points marked on the cardiac signal, and wherein the points are defined by fractional-phase transition points of each of the plurality of frequency components.
16. The computer-implemented method of claim 4 , wherein the automatically generating and outputting of representations of segments of the cardiac signal includes graphically presenting the cardiac signal with a plurality of points marked on the cardiac signal, and wherein the plurality of points are defined by fractional-phase transitions of each of a plurality of the frequency components, and wherein each of the plurality of points is labeled with a vector representation of one of the series of states.
17. The computer-implemented method of claim 4 , wherein the automatically generating and outputting of representations of segments of the cardiac signal includes graphically presenting the cardiac signal with a plurality of points marked by vertical lines on the cardiac signal, and wherein the plurality of points are defined by fractional-phase transitions of each of a plurality of the frequency components.
18. The computer-implemented method of claim 4 , wherein the automatically generating and outputting of representations of segments of the cardiac signal includes graphically presenting the cardiac signal with end points of the segments being defined by quarter-phase transition points on each of a plurality of frequency components.
19. A non-transitory computer-readable medium having instructions stored thereon, wherein the instructions when executed on a suitable information processor, perform a method comprising:
obtaining a digitized signal having a series of digital values of a quasi-periodic waveform, wherein the quasi-periodic waveform includes a cardiac signal;
generating a series of states defined by phase relationships between a plurality of frequency components of the cardiac signal based on the series of digital values; and
automatically generating and outputting representations of segments of the cardiac signal based on the series of states.
20. The computer-readable medium of claim 19 , further comprising instructions such that the generating of the series of states further includes:
frequency filtering the cardiac signal into a plurality of frequency bands of a plurality of different frequencies, wherein each one of the plurality of frequency bands corresponds to one of the plurality of frequency components;
generating a plurality of fractional phase representations, wherein each one of the plurality of fractional-phase representations corresponds to one of the plurality of frequency bands; and
determining the series of states based on a sequence of phases in the plurality of fractional-phase representations.
21. The computer-readable medium of claim 19 , further comprising instructions such that the automatically generating and outputting representations of segments of the cardiac signal includes creating graphical representations of the segments of the cardiac signal.
22. The computer-readable medium of claim 19 , further comprising instructions such that the generating of the series of states further includes:
frequency filtering the cardiac signal into a plurality of frequency bands of a plurality of different frequencies, wherein each one of the plurality of frequency bands corresponds to one of the plurality of frequency components;
generating a plurality of fractional phase representations, wherein each one of the plurality of fractional-phase representations corresponds to one of the plurality of frequency bands;
determining the series of states based on a sequence of phases in the plurality of fractional-phase representations, wherein each of the plurality of fractional phase representations includes a plurality of fractional phases, wherein each fractional phase is associated with a phase label and includes one or more values representing at least one of an abscissa and an ordinate for each of one or more local cycles of the cardiac signal.
23. The computer-readable medium of claim 19 , further comprising instructions such that the generating of the series of states further includes:
frequency filtering the cardiac signal into a plurality of frequency bands of a plurality of different frequencies, wherein each one of the plurality of frequency bands corresponds to one of the plurality of frequency components;
generating a plurality of fractional phase representations, wherein each one of the plurality of fractional-phase representations corresponds to one of the plurality of frequency bands;
determining the series of states based on a sequence of phases in the plurality of fractional-phase representations, wherein the series of digital values are complex numbers, and wherein each one of the plurality of fractional-phase representations is associated with an angular range of a complex argument of the cardiac signal.
24. The computer-readable medium of claim 19 , further comprising instructions such that the automatically generating and outputting of the representations of segments of the cardiac signal includes graphically presenting the cardiac signal with points marked on the cardiac signal, and wherein the points are defined by fractional-phase transition points of each of the plurality of frequency components.
25. The computer-readable medium of claim 19 , further comprising instructions such that the automatically generating and outputting of representations of segments of the cardiac signal includes graphically presenting the cardiac signal with a plurality of points marked on the cardiac signal, and wherein the plurality of points are defined by fractional-phase transitions of each of a plurality of the frequency components, and wherein each of the plurality of points is labeled with a vector representation of one of the series of states.
26. The computer-readable medium of claim 19 , further comprising instructions such that the automatically generating and outputting of representations of segments of the cardiac signal includes graphically presenting the cardiac signal with a plurality of points marked by vertical lines on the cardiac signal, and wherein the plurality of points are defined by fractional-phase transitions of each of a plurality of the frequency components.