A real time FFT-based impedance meter with bias compensation

A real time FFT-based impedance meter is here presented. It is realized simply by a standard PC in addition to a low cost two channels hardware device, and is based on a cost-effective algorithm to meaningfully reduce the known problem of the bias introduced by the relative phase and amplitude error between channels. The impedance meter exploits the implementation of an ad hoc cost-effective algorithm and a synchronous sampling allows eliminating the leakage error. The aliasing and the spectral interference are eliminated by means of an anti-aliasing filter and the use of very low distortion sinusoidal signals. Automatic measurements can be managed too, capturing different measures at different test frequencies and displaying them graphically on the PC screen. To validate the measured results comparative test were performed with respect to certified and calibrated commercially available multimeters known with good accuracies. Finally, this novel impedance meter integrates a home-made software, previously reported [1] capable to implement real time virtual instruments. (C) 2011 Elsevier Ltd. All rights reserved.