Method and system for obtaining a first signal for analysis to characterize at least one periodic component thereof

• US 9,524,548 B2
• Filed: 12/22/2014
• Issued: 12/20/2016
• Est. Priority Date: 10/06/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Kirenko, Ihor Olehovych, Jeanne, Vincent, De Haan, Gerard, Van Leest, Adriaan Johan
• Primary Examiner(s): Harandi, Siamak
• Application Number:
  US14/578,587
• Publication Number:
  US 20150104088A1
• Time in Patent Office: 729 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: G06T 2207/30076 Plethysmography
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 7/0012 Biomedical image inspection

Abstract

A method of facilitating obtaining a first signal, for analysis to characterize at least one periodic component, includes obtaining two second signals representative of intensities of electromagnetic radiation. The first signal is at least derivable from an output signal obtainable by applying a transformation to the second signals such that any value of the output signal is based on values from each respective second signal at corresponding points in time. The method further includes obtaining a value of a variable determining influences of components of respective second signals on the output signal when the signals corresponding to the second signals are captured and the transformation is applied, by (i) analyzing the first, second and/or the output signals to select a value of a parameter corresponding to a respective one of the variables; or (ii) calculating values of at least one time-varying factor corresponding to a respective one of the variables.

Claims

1. A system for characterizing periodic component of a first signal, the system comprising a processor configured to:

obtain second signals representative of intensities of captured electromagnetic radiation, each corresponding to a respective different radiation frequency range;

analyze the second signals by applying a transformation to the second signals to form transformed signals such that any value of the transformed signals is based on values from each of the second signals at corresponding points in time;

combine the transformed signals into an output signal; and

obtain values of variables determining influences of components of the second signals on the output signal by at least one of;

select at least one value of at least one parameter corresponding to a respective one of the variables; and

calculate values of at least one time-varying factor corresponding to a respective one of the variables, and perform a normalization of the second signals using the calculated values.

2. The system of claim 1, wherein the processor is configured to use analysis of at least one of the second signals, the output signal and the first signal to select at least one value of at least one parameter determining influences of at least components of respective ones of the second signals on the output signal so as to maximize a relative signal strength in a limited part of a spectrum of the first signal.

3. The system of claim 1, wherein the transformation includes at least one parameterized operation, and wherein the processor is configured to use analysis of at least one of the second signals, the output signal and the first signal to select values of at least one parameter of the operation.

4. The system of claim 3, wherein the parameterized operation is an operation taking at least two inputs based in different ways on the second signals.

5. The system of claim 3, wherein the transformation includes an operation carried out in parallel on respective input signals using at least one parameter value specific to fewer than all of the input signals.

6. The system of claim 3, wherein the transformation includes at least one parameterized non-linear operation, and wherein the processor is configured to use analysis of at least one of the second signals, an output signal obtained by applying the transformation to the second signals and a further signal derived from the output signal to select values of at least one parameter of the parameterized operation.

7. The system of claim 1, wherein the transformation includes an operation carried out in parallel on respective input signals, each a different linear combination of the second signals with at least one coefficient differing from zero, and wherein the operation comprises taking a logarithm of the input signal.

8. The system of claim 1, wherein the processor is configured to analyze the second signals by carrying out a principal component analysis on data sets respectively based on the second signals.

9. The system of claim 1, wherein the processor is configured to analyze at least one of the second signals, an output signal obtained by applying the transformation to the second signals and the first signal derived from the output signal, and to use the analysis to select at least one value of at least one parameter determining influences of at least components of respective second signals on the output signal when signals corresponding to the second signals are captured and the transformation is applied, wherein the first signal is derivable from the output signal, wherein any value of the output signal is based on values from each respective second signal at a common point in time, and wherein the processor is further configured to determine influences of respective second signals on the output signal at least partly in accordance with the selected values of the at least one parameter.

10. The system of claim 1, wherein the processor is further configured to continually analyze at least one of the second signals, the output signal and the first signal derived from the output signal and select the at least one value of the at least one parameter, while processing the second signals to obtain the first signal.

11. The system of claim 1, wherein the processor is further configured to:

calculate values of at least one time-varying factor corresponding to a respective one of the variables, each factor value based on at least one second signal value, and

apply each factor in an operation in at least one of a number of parallel sequences of operations comprising at least one such operation and taking a signal corresponding to a respective one of the second signals as input,

wherein the at least one time-varying factor includes an obtainable factor obtainable by calculating a linear combination of corresponding values from each of at least one of the second signals, and

wherein a same value of the obtainable factor is used in each of the parallel sequences of operations.

12. The system of claim 1, wherein the processor is further configured to:

calculate values of at least one time-varying factor corresponding to a respective one of the variables, each factor value based on at least one second signal value, and

apply each factor in an operation in at least one of a number of parallel sequences of operations comprising at least one such operation and taking a signal corresponding to a respective one of the second signals as input, and

wherein, for at least one of the factors, separate values at corresponding associated points in time are calculated for each of the parallel sequences, each obtained from multiple values of the second signal taken as input by the sequence concerned, the multiple values being associated with respective points in time spanning an interval including the point in time associated with the factor value.

13. A non-transitory computer readable medium comprising computer instructions which, when executed by a processor, configure the processor to perform acts of:

obtaining two signals representative of intensities of captured electromagnetic radiation, each corresponding to a respective different radiation frequency range;

analyzing the two signals by applying a transformation to the two signals to form transformed signals such that any value of the transformed signals is based on values from each of the two signals at corresponding points in time;

combining the transformed signals into an output signal; and

obtaining values of variables determining influences of components of the two signals on the output signal by at least one of;

selecting at least one value of at least one parameter corresponding to a respective one of the variables; and

calculating values of at least one time-varying factor corresponding to a respective one of the variables, and performing a normalization of the two signals using the calculated values.

14. The non-transitory computer readable medium of claim 13, wherein the instructions, when executed by the processor, further configure the processor to use analysis of at least one of the second signals, the output signal and the first signal to select at least one value of at least one parameter determining influences of at least components of respective ones of the second signals on the output signal so as to maximize a relative signal strength in a limited part of a spectrum of the first signal.

15. The non-transitory computer readable medium of claim 13, wherein the transformation includes at least one parameterized operation, and wherein the instructions, when executed by the processor, further configure the processor to use analysis of at least one of the second signals, the output signal and the first signal to select values of at least one parameter of the operation.

16. The non-transitory computer readable medium of claim 15, wherein the parameterized operation is an operation taking at least two inputs based in different ways on the second signals.

17. The non-transitory computer readable medium of claim 15, wherein the transformation includes an operation carried out in parallel on respective input signals using at least one parameter value specific to fewer than all of the input signals.

18. The non-transitory computer readable medium of claim 15, wherein the transformation includes at least one parameterized non-linear operation, and wherein the instructions, when executed by the processor, further configure the processor to use analysis of at least one of the second signals, an output signal obtained by applying the transformation to the second signals and a further signal derived from the output signal to select values of at least one parameter of the parameterized operation.

19. The non-transitory computer readable medium of claim 13, wherein the transformation includes an operation carried out in parallel on respective input signals, each a different linear combination of the second signals with at least one coefficient differing from zero, and wherein the operation comprises taking a logarithm of the input signal.

20. The non-transitory computer readable medium of claim 13, wherein the instructions, when executed by the processor, further configure the processor to analyze the second signals by carrying out a principal component analysis on data sets respectively based on the second signals.

21. The non-transitory computer readable medium of claim 13, wherein the instructions, when executed by the processor, further configure the processor to analyze at least one of the second signals, an output signal obtained by applying the transformation to the second signals and the first signal derived from the output signal, and to use the analysis to select at least one value of at least one parameter determining influences of at least components of respective second signals on the output signal when signals corresponding to the second signals are captured and the transformation is applied, wherein the first signal is derivable from the output signal, wherein any value of the output signal is based on values from each respective second signal at a common point in time, and wherein the processor is further configured to determine influences of respective second signals on the output signal at least partly in accordance with the selected values of the at least one parameter.

22. The non-transitory computer readable medium of claim 13, wherein the instructions, when executed by the processor, further configure the processor to continually analyze at least one of the second signals, the output signal and the first signal derived from the output signal and select the at least one value of the at least one parameter, while processing the second signals to obtain the first signal.

23. The non-transitory computer readable medium of claim 13, wherein the instructions, when executed by the processor, further configure the processor to:

calculate values of at least one time-varying factor corresponding to a respective one of the variables, each factor value based on at least one second signal value, and

apply each factor in an operation in at least one of a number of parallel sequences of operations comprising at least one such operation and taking a signal corresponding to a respective one of the second signals as input,

wherein the at least one time-varying factor includes an obtainable factor obtainable by calculating a linear combination of corresponding values from each of at least one of the second signals, and

wherein a same value of the obtainable factor is used in each of the parallel sequences of operations.

24. The non-transitory computer readable medium of claim 13, wherein the instructions, when executed by the processor, further configure the processor to:

calculate values of at least one time-varying factor corresponding to a respective one of the variables, each factor value based on at least one second signal value, and

apply each factor in an operation in at least one of a number of parallel sequences of operations comprising at least one such operation and taking a signal corresponding to a respective one of the second signals as input, and

wherein, for at least one of the factors, separate values at corresponding associated points in time are calculated for each of the parallel sequences, each obtained from multiple values of the second signal taken as input by the sequence concerned, the multiple values being associated with respective points in time spanning an interval including the point in time associated with the factor value.