Improve wavelet transform spectrum measurement performance by means of variable mother function bandwidth parameter

This paper indicates that although wavelet transform is advantageous for transient signal analysis, it is difficult to apply for signal spectrum measurement due to its auto resolution adjustment ability that gives poor frequency resolution at high frequency and makes frequency spectrum unidentifiable. To overcome this shortfall, the paper proposes a new approach that replaces the constant Morlet wavelet mother function bandwidth parameter with a variable one, so that the expanding of bandwidth of Morlet wavelet transform is restricted in high frequency, resulting in better frequency resolution. The experimental signals are calculated spectrum with both original and improved Morlet wavelet transforms and the improvements of the spectrum measurement are obvious and accord well with the theoretical analysis of this paper.