电容层析成像系统中的相敏解调

Phase sensitive demodulation in ECT system

电容层析成像是通过传感器阵列电极电容的变化,反映管道中多相介质的分布,从而重建管道截面各相介质的分布图像。其中,相敏解调是关键的环节。本文介绍了电容层析成像系统常用的几种相敏解调的方法,包括模拟解调和数字解调方法。由于模拟器件本身的弊端,制约了系统实时性和精度的提高。本文设计的数字化系统,充分利用FPGA和DSP,实现了全数字正交序列解调,系统的速度和精度都得到了提高。

Electrical capacitance tomography （ECT） techniques have been developed to visualize industrial processes with dielectric materials. Phase sensitive demodulation is a key part of ECT system. Methods of demodulation are demonstrated in this paper, including analogue and digital methods. The shortcomings of analogue devices have been a bottleneck of development of the system. A digital ECT system is designed in this paper which makes full use of FPGA and DSP, and realizes the full digital quadrature demodulation. Both the systematic speed and precision are improved.