Systems and methods for identifying pulse rates

Abstract

According to embodiments, techniques for using continuous wavelet transforms and spectral transforms to identify pulse rates from a photoplethysmographic (PPG) signal are disclosed. According to embodiments, candidate pulse rates of the PPG signal may be identified from a wavelet transformed PPG signal and a spectral transformed PPG signal. A pulse rate may be determined from the candidate pulse rates by selecting one of the candidate pulse rates or by combining the candidate pulse rates. According to embodiments, a spectral transform of a PPG signal may be performed to identify a frequency region associated with a pulse rate of the PPG signal. A continuous wavelet transform of the PPG signal at a scale corresponding to the identified frequency region may be performed to determine a pulse rate from the wavelet transformed signal.

1 . A method for determining a pulse rate from a photoplethysmographic (PPG) signal, comprising:
 receiving a PPG signal;   performing a spectral transform of the PPG signal to produce a spectrum;   identifying from the spectrum a frequency region associated with a pulse rate of the PPG signal;   performing a continuous wavelet transform of the PPG signal at a scale corresponding to the identified frequency region to produce a wavelet transformed signal; and   determining a pulse rate from the wavelet transformed signal.   
     
     
         2 . The method of  claim 1  wherein the spectral transform comprises a Fourier transform. 
     
     
         3 . The method of  claim 1  wherein identifying the frequency region associated with a pulse rate of the PPG signal comprises identifying peaks in the spectrum. 
     
     
         4 . The method of  claim 1  wherein performing the wavelet transform comprises performing a continuous wavelet transform of the PPG at a plurality of scales corresponding to the identified frequency region to produce the wavelet transformed signal. 
     
     
         5 . The method of  claim 1  wherein determining the pulse rate from the wavelet transformed signal comprises determining a set of pulse rates over time. 
     
     
         6 . A system for determining a pulse rate from a photoplethysmographic (PPG) signal, comprising:
 a spectral processor capable of performing a spectral transform of a received PPG signal to produce a spectrum and identifying a frequency region associated with a pulse rate of the PPG signal from the spectrum; and   a wavelet processor capable of performing a continuous wavelet transform of the received PPG signal at a scale corresponding to the identified frequency region to produce a wavelet transformed signal and determining a pulse rate from the wavelet transformed signal.   
     
     
         7 . The system of  claim 6  wherein the spectral transform comprises a Fourier transform. 
     
     
         8 . The system of  claim 6  wherein the spectral processor is capable of identifying peaks in the spectrum to identify the frequency region associated with the pulse rate. 
     
     
         9 . The system of  claim 6  wherein the wavelet processor is capable of performing a continuous wavelet transform of the PPG at a plurality of scales corresponding to the identified frequency region to produce the wavelet transformed signal. 
     
     
         10 . The system of  claim 6  wherein the wavelet processor is capable of determining a set of pulse rates over time. 
     
     
         11 . Computer-readable medium for use in determining a pulse rate from a photoplethysmographic (PPG) signal, the computer-readable medium having computer program instructions recorded thereon, wherein the computer program instructions, when executed on a processor, cause the processor to:
 perform a spectral transform of a PPG signal to produce a spectrum;   identify from the spectrum a frequency region associated with a pulse rate of the PPG signal;   perform a continuous wavelet transform of the PPG signal at a scale corresponding to the identified frequency region to produce a wavelet transformed signal; and   determine a pulse rate from the wavelet transformed signal.   
     
     
         12 . The computer-readable medium of  claim 11  wherein the spectral transform comprises a Fourier transform. 
     
     
         13 . The computer-readable medium of  claim 11  wherein the computer program instructions, when executed on a processor, further identify peaks in the spectrum. 
     
     
         14 . The computer-readable medium of  claim 11  wherein the computer program instructions, when executed on a processor, further cause the processor to perform a continuous wavelet transform of the PPG at a plurality of scales corresponding to the identified frequency region to produce the wavelet transformed signal. 
     
     
         15 . The computer-readable medium of  claim 11  wherein the computer program instructions, when executed on a processor, further cause the processor to determine a set of pulse rates over time.