Selection of excitation signals for high-impedance spectroscopy

Abstract

The method of fast impedance spectroscopy of technical objects with high impedance (|Zx| > 1 GΩ) is evaluated in this paper. An object is excited with a signal generated by digital-to-analog converter (DAC) located on the U2531A DAQ module. Response signals proportional to current flowing through and voltage across the measured object are sampled by analog-to-digital converters (ADC) in the DAQ module. The object impedance spectrum is obtained with use of continuous Fourier transform on the basis of acquired signals. Different excitation signals (square, triangle, sawtooth and sinc) were compared in order to estimate accuracy of impedance spectrum evaluation. The method is evaluated by means of simulation and practical experiment in a measuring system on an exemplary object in the form of multielement two-terminal RC network modelling of an anticorrosion coating impedance. © Published under licence by IOP Publishing Ltd.