Movement Artefact Resistant Photoplethysmographic Probe
Keywords: Photoplethysmography, signal to noise ratio, wearable device, Barker code, optical code sequences
AbstractPhotoplethysmogram (PPG) is an exceptionally informative diagnostic tool, but the signal registered by wearable devices usually is corrupted, because the probe is affected by the external force and moves with respect to the point of the measurement during the physical activities of the human. This problem is solved usually applying some techniques for the PPG extraction from the corrupted (noisy) signal. The authors of this paper are suggesting the solutions, which prevent corruption of PPG instead of noise filtering or other PPG extraction from corrupted signal techniques. One of such solutions is described in this paper, by proposing special photoplethysmographic signal probe (PPGP). This device emits the amplitude modulated light beam with special code sequence, which like Barker code, can be easily recognized using correlation method. The experimental evaluation of proposed method showed, that even in case of a very high noise level SNR=0dB correlation between reference PPG and photoplethysmogram got using proposed method is remarkable, reaching corr = 0.985, while standard deviation of error is small and equal std(err)=0.33.
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