Analysis of digital demodulation in MIT

Wang Ben Xu Kai Chen Guang Chen Li-jing Yin Wu-liang

(School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072, China)

ABSTRACT

Electromagnetic Tomography(EMT) is a process imaging technique based on magnetic induction principle. It reconstructs cross-sectional conductivity and permeability distribution in the object field. Phase sensitive demodulation is a key part of an EMT system. In this paper, we analyze several important issues in digital demodulation: 1. The error caused when there is a discrepancy between the frequency of the reference signal and the signal to be demodulated. 2. The relation between the periodicity of sampled signal and signal-to-noise ratio (SNR). 3. Explanations in frequency domain for the results obtained. Matlab simulation results are presented.

Keywords EMT; Digital demodulation; Frequency-domain analysis; Periodicity