A Technique to Reduce Information Loss in PPG Pulse Waveform Refining Processing

In order to conduct advanced signal processing techniques so as to extract reliable clinical information contained in photoplethsmographic (PPG) signal, PPG pulse waveform refining processing over a relatively wide range of the heart rate change is involved. The key point during this refining stage is to reduce the information loss caused by the waveform distortion so that the signal energy can be accumulated as coherently as possible. In this respect, however, the conventional time-scale-normalization technique will meet serious difficulty. To overcome this difficulty, a PPG pulse waveform refining processing technique, named truncation/extrapolation technique, is proposed in this paper. The rationale of the proposed technique is to preserve the shape pattern of the most significant parts of the pulse waveform at the expanse of the distortion of the insignificant part. Analysis and comparison between two techniques verify the effectiveness of the proposed method