The Design of a Digital Magnetic Induction Tomography (MIT) System for Metallic Object Imaging Based on Half Cycle Demodulation

This paper presents several important aspects of a highly integrated, Field Programmable Gate Array (FPGA)-based digital Magnetic Induction Tomography (MIT) system for metallic object imaging applications. Excitation signal generation, receiving signal demodulation, and channel multiplexing control are all implemented inside a Xilinx FPGA (Spartan III). A novel digital demodulation method using only half of the signal cycle is proposed and implemented, which improves the operation speed of the system by two folds. A geometrical scaling relationship has been discovered for MIT sensors, and a particular design has been implemented. Two imaging reconstruction algorithms (Tikhonov Regularization and Total Variation method) are applied to experimental data. The performance of the system has been verified.