Method using square pulse excitation for high-impedance spectroscopy of anticorrosion coatings

The paper presents a method of impedance spectroscopy designed for a diagnostics of anticorrosion coatings on objects directly in the field. To shorten the time of impedance spectrum estimation (in the range from 1 mHz to 1 MHz) down to a few minutes, harmonic signals were used to determine the spectrum above 100 Hz and a square pulse in the low frequency range. To determine the impedance spectrum DSP algorithms adequate to the excitation signal were used. In the high frequency range DFT was used, but in the low frequency range continuous Fourier transformation calculated in 8 segments of acquisition, which are dependent on pulse duration time. The performed simulation tests proved the usefulness of the method for impedance spectroscopy of anticorrosion coatings with a relative error of the impedance modulus ±1% and absolute error of the impedance argument ±0.5°.