The capabilities related to active filtering of the Stationary Wavelet Transform — SWT were evaluated considering 3 Daubechy wavelet mothers. Firstly a study on errors was performed on synthetic waveforms. The waveforms were obtained from sinusoids polluted by single harmonics with orders from the range 3…40 and magnitudes, respectively phase differences varied in a systematic manner. The differences between the fundamental components (synthetic vs value yielded by SWT) were evaluated with 2 metrics: extreme values and RMSD. 3D representations of the metrics are provided, along with a study of instantaneous values of errors. Afterward 3 sets of signals polluted by 4 harmonics were decomposed. Low harmonics, high harmonics and respectively mixed harmonics were used. A study of errors was performed again. At the end the algorithm was applied over real data. A comparison to FFT analysis results was made. Conclusions on the usability of each of the studied wavelet mother are drawn.