Signal Demodulation Methods for Electrical Tomography: A Review

The amplitude and phase of each sinusoidal frequency component in a signal can be obtained by phase-sensitive demodulation, which is commonly used in electrical tomography (ET) and greatly influences the performance of the ET system. In the past decades, many demodulation methods have been developed for the ET system. This paper reviews the latest development in demodulation methods for the ET system, including the traditional methods and several newly proposed methods. To support the standpoints in the review, we implemented these methods in a self-made ECT system and then compared the performances of these methods, including the demands on hardware resources, demodulation time, and accuracy, by simulation and experiments. The main objective of the review is to provide guidance on the selection of appropriate demodulation method for a specific application.