The reassigned pseudo Wigner-Ville transform in electrochemical noise analysis

Several different time-frequency transforms from signal processing were used to analyze electrochemical noise data to determine frequency components contained within the noise record and their time evolution. Bilinear time-frequency representations (TFR) based on the Wigner-Ville distribution (WVD) were compared with a special focus on the reassigned smoothed pseudo WVD (RSPWVD). Spectra obtained with WVD were compared with traditional linear time-frequency representations, such as short time Fourier transform and wavelet transform. Comparison to other TFRs showed that the RSPWVD suppressed artifacts, provided better resolution of the time-frequency analysis in both time and frequency domains, and improved the overall readability of a representation. The obtained spectra from RSPWVD were consistent with the results from DWT, but permitted a more comprehensive analysis of transients. Consequently, RSPWVD is suitable for electrochemical noise analysis. In the presence of Cl-, RSPWVD showed that the passivity of Al was compromised, as evidenced by the presence of various current transients in the frequency range from 10(-2) to 1 Hz.