Denoising of Pulse Wave Signal by Wavelet Packet Transform

Aiming at the problem that it is impossible to extract accurate pulse wave characteristics such as pulse wave transit time (PTT) from single channel pulse wave signal with low sampling rate, a dual channel pulse wave signal measuring instrument with high sampling rate based on AFE4490 (analog front end) and STM32H743IIT6 (MCU) is designed. Through noise analysis of the dual channel pulse wave signals, the outliers, DC components, baseline drift and high frequency noise in pulse wave signals are removed by using location replacement, frequency domain and wavelet packet transform. Finally, in order to verify the accuracy of pulse wave signals, this paper designed the heart rate accuracy experiment and PTT value comparison experiment at different sampling rates. The results show that the dual channel pulse wave measuring instrument designed in this paper could accurately obtain heart rate and pulse wave transit time, and could collect correct and complete pulse wave signals.