Figure 4 | Scientific Reports

Figure 4

From: Accuracy and reliability of the optoelectronic plethysmography and the heart rate systems for measuring breathing rates compared with the spirometer

Figure 4

Plots of subjects’ breathing frequencies nearest to 0.25 Hz (15 breath/min) during the controlled 6-min breathing exercise performed using a fast Fourier transform. (a) OEP signal (frequency = 0.2472 Hz or 14.83 breath/min); (b) spirometer data (frequency = 0.248 Hz or 14.88 breath/min); (c) ECG data (frequency = 0.248 Hz or 14.88 breath/min) and (d) with RR-interval time series (frequency = 0.248 Hz or 14.88 breath/min).

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