Parallel-type fractional zero-phase filtering for ECG signal denoising

In this paper, a parallel-type fractional zero-phase filtering technique based on the center Grunwald-Letnikov differintegrator is proposed. We first present a left and a right Grunwald-Letnikov differintegrators, which are generalized magnitude-and-phase modulations. By using them in parallel we obtain a center Grunwald-Letnikov differintegrator, essentially a parallel-type fractional zero-phase filter. And then a center symmetrical convolution mask is constructed to implement the proposed fractional zero-phase filter. The method presented eliminates the phase distortion while offering a better compromise between signal denoising and signal information retention than convontional filtering methods. To illustrate this, the differintegrator and conventional filters were applied to electrocardiogram signals. The results indicate that the method we propose has superior performance compared with conventional denoising methods. (C) 2014 Elsevier Ltd. All rights reserved.