Noise Detection and Removing in Heart Sound Signals via Nuclear Norm Minimization Problems

Heart sound is an electric signal affected by some factors during the signal's recording process, which adds unwanted information to the signal. Recently, many studies have been interested in noise removal and signal recovery problems. The first step in signal processing is noise removal; many filters are used and proposed for treating this problem. Here, the Hankel matrix is implemented from a given signal and tries to clean the signal by overcoming unwanted information from the Hankel matrix. The first step is detecting unwanted information by defining a binary operator. This operator is defined under some threshold. The unwanted information replaces by zero, and the wanted information keeping in the estimated matrix. The resulting matrix contains zeros, so the problem is to find a low-rank matrix. Matrix completion is a heuristic NP-hard problem. It is a minimization problem defined by the matrix nuclear norm. In this paper, nuclear norm, and weighted nuclear norm minimization problems are derived to find a low-rank matrix of implemented Hankel matrix from the signal. A Robust Principal Component used to solve a low-rank-sparse matrix finds a low-rank Hankel matrix by solving a minimization problem numerically. The results show that the given methods are efficient in reconstructing and recovering the signals with a rate of more than 96%, with small values of mean square errors.