Proposal of advanced nonlinear signal model to analyze photoplethysmogram signals

This paper proposes an advanced nonlinear signal model to handle the intrinsic nonlinearity of the pulsation of photoplethysmogram (PPG) signals and so permit their assessment. This model consists of three-different sinusoidal source signals and it successfully reproduces the primary harmonic, the second harmonic, the respiratory and the other spectra stemming from the interaction of the three source signals. We demonstrate the potential of the model in various experiments on PPG signals. It is discovered that the model reproduces the specific spectral intensity ratio zone (specific SIRZ) that is defined for the purpose of alcohol-intake detection.