METHODS AND SYSTEMS FOR FILTERING A SIGNAL ACCORDING TO A SIGNAL MODEL AND CONTINUOUS WAVELET TRANSFORM TECHNIQUES

• US 20120302895A1
• Filed: 07/31/2012
• Published: 11/29/2012
• Est. Priority Date: 07/15/2008
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Watson, James Nicholas, Addison, Paul Stanley
• Granted Patent: US 9,259,188 B2
• Time in Patent Office: Days
• US Class Current: 600/479
• 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 are provided for filtering a signal. A first reference signal may be generated according to a signal model and a second reference signal may be generated by analyzing a continuous wavelet transform of a signal. The first and second reference signals may then both be applied to an input signal to filter the input signal according to the components of both of the reference signals.

Claims

1. A method for determining a physiological parameter, the method comprising:

receiving, using a processor, a first input signal corresponding to a first wavelength of light and a second input signal corresponding to a second wavelength of light;

generating, using a processor, a first scalogram based on a wavelet transform of the first input signal;

generating, using a processor, a second scalogram based on a wavelet transform of the second input signal;

summing, using a processor, the first scalogram and the second scalogram to generate a modified scalogram; and

determining, using a processor, the physiological parameter based on the modified scalogram.

2. The method of claim 1, wherein summing the first scalogram and the second scalogram comprises summing coefficients of the first scalogram and the second scalogram at each scale and time.

3. The method of claim 1, further comprising scaling at least one of the first scalogram and the second scalogram before summing the first scalogram and the second scalogram.

4. The method of claim 3, wherein the scaling is based on noise.

5. The method of claim 3, wherein the scaling normalizes the first scalogram and the second scalogram.

6. The method of claim 1, wherein a characteristic of the wavelet transform of the first input signal is different than a characteristic of the wavelet transform of the second input signal.

7. The method of claim 1, wherein the physiological parameter is selected from the group comprising pulse rate and respiration rate.

8. A system for determining a physiological parameter, the system comprising:

a processor configured to;

receive a first input signal corresponding to a first wavelength of light and a second input signal corresponding to a second wavelength of light;

generate a first scalogram based on a wavelet transform of the first input signal;

generate a second scalogram based on a wavelet transform of the second input signal;

sum the first scalogram and the second scalogram to generate a modified scalogram; and

determine the physiological parameter based on the modified scalogram.

9. The system of claim 8, wherein the processor is configured to sum coefficients of the first scalogram and the second scalogram at each scale and time.

10. The system of claim 8, wherein the processor is further configured to scale at least one of the first scalogram and the second scalogram before summing the first scalogram and the second scalogram.

11. The system of claim 10, wherein the processor is configured to scale based on noise.

12. The system of claim 10, wherein the processor is configured to scale at least one of the first scalogram and the second scalogram to normalize the first scalogram and the second scalogram.

13. The system of claim 8, wherein a characteristic of the wavelet transform of the first input signal is different than a characteristic of the wavelet transform of the second input signal.

14. The system of claim 8, wherein the physiological parameter is selected from the group comprising pulse rate and respiration rate.

15. A non-transitory computer-readable medium for use in determining a physiological parameter, the non-transitory computer-readable medium having computer program instructions recorded thereon for:

receiving a first input signal corresponding to a first wavelength of light and a second input signal corresponding to a second wavelength of light;

generating a first scalogram based on a wavelet transform of the first input signal;

generating a second scalogram based on a wavelet transform of the second input signal;

summing the first scalogram and the second scalogram to generate a modified scalogram; and

determining the physiological parameter based on the modified scalogram.

16. The non-transitory computer-readable medium of claim 15, wherein summing the first scalogram and the second scalogram comprises summing coefficients of the first scalogram and the second scalogram at each scale and time.

17. The non-transitory computer-readable medium of claim 15, having further computer program instructions recorded thereon for scaling at least one of the first scalogram and the second scalogram before summing the first scalogram and the second scalogram.

18. The non-transitory computer-readable medium of claim 17, wherein the scaling is based on noise.

19. The non-transitory computer-readable medium of claim 17, wherein the scaling normalizes the first scalogram and the second scalogram.

20. The non-transitory computer-readable medium of claim 15, wherein a characteristic of the wavelet transform of the first input signal is different than a characteristic of the wavelet transform of the second input signal.

21. The non-transitory computer-readable medium of claim 15, wherein the physiological parameter is selected from the group comprising pulse rate and respiration rate.