Energy concentration enhancement using window width optimization in S transform

The S transform is a useful time-frequency analysis algorithm. Based on the concentration measure, a method to optimize the window width in the S transform has been proposed by previous studies along with some examples demonstrating its effectiveness. However, it is found that although this method performs well for the high and middle frequency signals, it may fail for the low frequency ones. In this paper, a new method, which is more flexible than the previous one, is proposed to deal with this problem. Comparison of these two methods for energy concentration enhancement is also provided. Experimental result shows that the proposed method achieves higher energy concentration in comparison to the previous one and the original ST.