Hardware Design for Quadrature Phase Detection Algorithm in ECVT

Core processing for calculating phase andamplitude of the detected signal was built on FPGA (Field-Programmable Gate-Array) platform. Phase shift demodulationalgorithm employs IP core provided by Xilinx FPGA. Directdigital synthesizer (DDS), multiplier, accumulator, and CORDIC(coordinate rotation digital computer) modules were used asexcitation-reference signal generator, signal multiplication,accumulation, and conversion to polar coordinate in order toconduct trigonometric operation respectively. Hardware designwas emulated on MATLAB-Xilinx System Generator to observeits performance. Phase detection range 0-114.58o and meanabsolute error 0.58o have been achieved. Data processing ratesolely at digital signal stage was approximately 100data/s suitablefor 32-channel ECVT (electrical capacitance volumetomography) system

An FPGA-based lock-in detection system to enable chemical species tomography using TDLAS

This paper presents the design, implementation and test of a compact, low-cost and fully digital signal recovery system for tunable diode laser absorption spectroscopy (TDLAS) in narrow line-width gas sensing applications. An FPGA-based digital lock-in amplifier (DLIA), in conjunction with TDLAS using the wavelength modulation spectroscopy (WMS) technique, is utilized to demodulate and extract first (1f) and second (2f) harmonic signals for a narrow CO2 feature in the spectrum region of 1997.2nm. The spectrum in this wavelength region shows suitably weak water absorption, enabling CO2 detection with high resolution. Gas-cell experiments were carried out using the DLIA and a conventional rack-mounted commercial lock-in amplifier. The comparison between the two systems shows good agreement, validating the feasibility of this approach and demonstrating the prospect for extension to a massively multichannel system to implement Chemical Species Tomography

Electrical Capacitance Volume Tomography (ECVT) for industrial and medical applications-An Overview

Tomography is a non-invasive, non-intrusive imaging technique allowing the visualization of phase dynamics in industrial and biological processes. This article reviews progress in Electrical Capacitance Volume Tomography (ECVT). ECVT is a direct 3D visualizing technique, unlike three-dimensional imaging, which is based on stacking 2D images to obtain an interpolated 3D image. ECVT has recently matured for real time, non-invasive 3-D monitoring of processes involving materials with strong contrast in dielectric permittivity. In this article, ECVT sensor design, optimization and performance of various sensors seen in literature are summarized. Qualitative Analysis of ECVT image reconstruction techniques has also been presented