SYSTEMS AND METHODS FOR GENERATING REFERENCE SIGNALS

• US 20100016696A1
• Filed: 10/03/2008
• Published: 01/21/2010
• Est. Priority Date: 07/15/2008
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Addison, Paul Stanley, Watson, James Nicholas
• Granted Patent: US 9,066,691 B2
• Time in Patent Office: Days
• US Class Current: 600/331
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

According to embodiments, systems and methods for generating reference signals are provided. A signal may be transformed using a continuous wavelet transform, Regions of interest may be selected from a transform or the resulting scalogram that may be used to generate a reference signal to use in filtering the signal or other signals. Cross-correlation techniques may be used to cancel noise components or isolate non-noise components from the signal. A physiological parameter may then be determined from the filtered signal or isolated components in the signal.

Claims

1. A method for generating a reference signal, comprising:

receiving an input signal;

performing a continuous wavelet transform of the input signal to produce a transformed input signal;

generating a scalogram from the transformed input signal;

identifying regions in the scalogram corresponding to desired components of the input signal; and

generating the reference signal based at least in part on the identified regions.

2. The method of claim 1, wherein generating the reference signal comprises performing an inverse continuous wavelet transform on the at least part of the transformed input signal.

3. The method of claim 1, wherein identifying regions in the scalogram comprises identifying at least one noise component in the scalogram.

4. The method of claim 1, wherein identifying regions in the scalogram comprises identifying at least one non-noise component in the scalogram.

5. The method of claim 1, wherein the input signal comprises a photoplethysmograph (PPG) signal.

6. The method of claim 1 further comprising generating a second scalogram from the transformed input signal, wherein the second scalogram comprises a residual scalogram.

7. The method of claim 1 further comprising outputting the reference signal to an adaptive filter.

8. The method of claim 7 further comprising filtering the input signal using at least the adaptive filter and the reference signal to produce a filtered input signal.

9. The method of claim 8 wherein filtering the input signal comprises cross correlating the reference signal with the input signal.

10. The method of claim 8 further comprising determining a physiological parameter based at least in part on the filtered input signal.

11. A system for generating a reference signal, comprising:

a sensor capable of generating an input signal; and

a processor capable of;

performing a continuous wavelet transform of the input signal to produce a transformed input signal;

generating a scalogram from the transformed input signal;

identifying regions in the scalogram corresponding to desired components of the input signal; and

generating the reference signal based at least in part on the identified regions.

12. The system of claim 11, wherein the processor is capable of performing an inverse continuous wavelet transform on the at least part of the transformed input signal.

13. The system of claim 11, wherein the processor is capable of identifying at least one noise component in the scalogram.

14. The system of claim 11, wherein the processor is capable of identifying at least one non-noise component in the scalogram.

15. The system of claim 11, wherein the input signal comprises a photoplethysmograph (PPG) signal.

16. The system of claim 11 wherein the processor is capable of generating a second scalogram from the transformed input signal, wherein the second scalogram comprises a residual scalogram.

17. The system of claim 11 wherein the processor is capable of outputting the reference signal to an adaptive filter.

18. The system of claim 17 wherein the processor is capable of filtering the input signal using at least the adaptive filter and/or the reference signal to produce a filtered input signal.

19. The system of claim 18 wherein the processor is capable of cross correlating the reference signal with the input signal.

20. The system of claim 18 wherein the processor is capable of determining a physiological parameter based at least in part on the filtered input signal.

21. A computer-readable medium for use in generating a reference signal, the computer-readable medium having computer program instructions recorded thereon for:

receiving an input signal;

performing a continuous wavelet transform of the input signal to produce a transformed input signal;

generating a scalogram from the transformed input signal;

identifying regions in the scalogram corresponding to desired components of the input signal; and

generating the reference signal based at least in part on the identified regions.