Figure 4.
(a) Amplitude increase in signal due to activity of auto-gain function. The microcontroller samples the dataset for the full sampling period, then adjusts the gain of the active filters to module signal amplitude. (b) Real-time, on-board signal processing of heart and respiratory signals after a very stressful event. The refresh rate of the display is such that heart rate (HR) and respiratory rate (RR) could not be captured in a single photograph at the same time. Additionally, there is a few seconds delay between each snapshot resulting in the difference in HR and RR reported by the reference device (viewed on the smartphone), which has a faster refresh rate than the experimental device.