Wavelet-based coherence analysis of rPPG and PPG signals in time-frequency domain for physiological monitoring
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Abstract
Spectral and time-frequency accuracy of remote photoplethysmography (rPPG) signals must be critically evaluated to bridge the gap with contact PPG measurements, with the aim of improving remote monitoring for low-quality cameras. This study presents a time-frequency coherence analysis based on wavelet transform to assess the synchronization and accuracy between rPPG and PPG signals. Aim of the study is to use continuous wavelet transform (CWT) and wavelet coherence to quantify the time-varying spectral correlation between the two signals. The method identifies dominant frequency bands and phase relationships associated with physiological parameters (e.g., heart rate, respiratory rate), while simultaneously assessing the effects of motion artifacts and environmental noise. Experimental results demonstrate that wavelet coherence provides a robust framework for comparing rPPG and PPG in dynamic scenarios, revealing key insights into signal reliability and potential compensation strategies. Research result improves the understanding of rPPG signal quality and supports its application in wearable devices, telemedicine and remote patient monitoring.
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References
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