Novel Signal Noise Reduction Method through Cluster Analysis, Applied to Photoplethysmography

Figure 1

Three recorded photoplethysmography (PPG) traces measured from the great toe site. Upper: a clean PPG signal; middle: a signal dominated by low-frequency noise, usually caused by movement of the subject’s limb; lower: a PPG trace contaminated with high-frequency noise, typical of electrical interference. Typically, these noise features can appear intermittently within a recording made over a measurement period of 1-2 minutes.