Heart Sound (PCG) Signal Compression based on Down-sampling and two-dimensionalization

Document Type : Original Article


1 Shahrood University of Technology

2 Department of Electrical and Robotics Engineering, Shahrood, Iran


In this paper, a lossy compression method with the ability to control the quality of the reconstructed signal is proposed for phonocardiography (PCG) signals. It is based on two main ideas: down-sampling and two-dimensionalization. For PCG image compression, wavelet transform and Spatial-oriented Tree Wavelet (STW) encoder are used. In the proposed method, there is the ability to control the quality of the reconstructed signal using a Percent Root-mean-square Difference (PRD)-related threshold. The simulation results of the proposed method on some public databases indicates that the down-sampling stage has a significant effect on increasing the compression ratio especially in the case of databases with high sampling frequency. The next important factor in improving the compression efficiency of the proposed method is the use of two-dimensional PCG signal in order to take advantage of the inter-period redundancy in this type of repetitive signals, and using modern effective methods for image compression. The efficiency of the proposed method was evaluated according to the average PRD and Compression Ratio (CR) criteria and compared with the results of several existing methods. In this evaluation, while limiting PRD≤5%, the lowest average compression ratio was related to the Artifacts dataset from the Pascal database (with a sampling frequency of 2000 Hz) and the highest average compression ratio was related to the database of the University of Washington (with a sampling frequency of 44100 Hz).


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