Application of an improved wavelet threshold algorithm in pulse measuring instrument

摘要

Aiming at the problem that the wavelet threshold algorithm is poor denoising effect in traditional pulse measuring instrument, an adaptive filtering algorithm of improved wavelet threshold function and threshold estimation is proposed in this system. This algorithm is used to eliminate the constant deviation of soft threshold function and the discontinuous shortcomings of hard threshold function by constructing a new threshold function and threshold estimation method and adjusting the adaptive adjustment coefficient, thus filtering out the interference noise in photoplethysmograph signals. The light intensity signals acquired by the photoelectric sensor are sequentially processed by signal amplifying circuit and filter circuit, the pho-toplethysmography signals are transmitted into LPC2103 for further processing, the results are displayed on the LCD screen. Experiments show that the improved wavelet threshold algorithm not only preserves the useful signal, but also avoids the oscillation. The algorithm is employed to denoise the pulse wave, which effectively improves the accuracy of the pulse measuring instrument.