Classical low-pass filter and real-time wavelet-based denoising technique implemented on a DSP: a comparison study^*

Groupe de Recherche en Informatique, Image et Instrumentation de Caen (CNRS UMR 6072), ISMRA et Université de Caen, 6 Bd du Maréchal Juin, 14050 Caen Cedex, France

Corresponding author: C.Dolabdjian@greyc.ismra.fr

Received: 13 November 2001
Accepted: 8 January 2002
Published online: 25 October 2002

Abstract

We have implemented a real-time numerical denoising algorithm, using the Discrete Wavelet Transform (DWT), on a TMS320C3x Digital Signal Processor (DSP). We also compared from a theoretical and practical viewpoints this post-processing approach to a more classical low-pass filter. This comparison was carried out using an ECG-type signal (ElectroCardiogram). The denoising approach is an elegant and extremely fast alternative to the classical linear filters class. It is particularly adapted to non-stationary signals such as those encountered in biological applications. The denoising allows to substantially improve detection of such signals over Fourier-based techniques. This processing step is a vital element in our acquisition chain using high sensitivity magnetic sensors. It should enhance detection of cardiac-type magnetic signals or magnetic particles in movement.