Signal processor, signal processing method, and recording medium

• US 9,962,126 B2
• Filed: 12/06/2013
• Issued: 05/08/2018
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Maeda, Kazuho, Sakata, Masato, Uchida, Daisuke, Inomata, Akihiro
• Primary Examiner(s): Ngon, Ricky
• Application Number:
  US14/099,457
• Publication Number:
  US 20140276114A1
• Time in Patent Office: 1,614 Days
• Field of Search: 702189
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/0082 adapted for particular medical purposes
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity

Abstract

A pulse wave detection apparatus detects a signal, and calculates a correlation coefficient between waveforms of the signal included in a first window and a second window having a predetermined duration, the correlation coefficient being smaller when a difference between dispersion of the amplitude value in the first window and dispersion of the amplitude value in the second window becomes larger.

Claims

1. A signal processor comprising:

a memory; and

a processor coupled to the memory, wherein the processor executes a process comprising;

detecting a signal;

calculating a correlation coefficient between waveforms of the signal included in a first window and a second window having a predetermined duration;

correcting the correlation coefficient such that the larger a difference between dispersion of the amplitude value in the first window and dispersion of the amplitude value in the second window becomes, the smaller the correlation coefficient becomes, by selecting a larger dispersion out of the dispersion in the first window and the dispersion in the second window and using the selected dispersion by a following equation;

2. The signal processor according to claim 1, wherein the process further comprises:

transition determining whether the positive and negative of the amplitude value of the signal transitions to determine a transition point at which the positive and negative of the amplitude value transitions, and wherein

the first setting includes setting the duration of the first window to a duration containing transition points the number of which corresponds to the integral multiple of a cycle of the pulse wave.

3. The signal processor according to claim 1, wherein the process further comprises:

determining whether the amplitude value of the signal is an extreme value, and wherein

the second setting includes setting of the range when the number of the local maximum points included in the first window out of the local maximum points determined as the local maximum at the determining is equal to the number corresponding to the cycle of the pulse wave.

4. The signal processor according to claim 1, wherein

the second setting includes setting the range using the duration set to the first window at the first setting.

5. A signal processing method comprising:

detecting, using a processor, a signal;

calculating, using the processor, a correlation coefficient between waveforms of the signal included in a first window and a second window having a predetermined duration;

correcting, using the processor, the correlation coefficient such that the larger a difference between dispersion of the amplitude value in the first window and dispersion of the amplitude value in the second window becomes, the smaller the correlation coefficient becomes, by selecting a larger dispersion out of the dispersion in the first window and the dispersion in the second window and using the selected dispersion by a following equation;

6. A non-transitory computer readable recording medium having stored therein a signal processing program that causes a computer to execute a process comprising:

detecting a signal;

calculating a correlation coefficient between waveforms of the signal included in a first window and a second window having a predetermined duration;

correcting the correlation coefficient such that the larger a difference between dispersion of the amplitude value in the first window and dispersion of the amplitude value in the second window becomes, the smaller the correlation coefficient becomes, by selecting a larger dispersion out of the dispersion in the first window and the dispersion in the second window and using the selected dispersion by a following equation;