Digital phase-sensitive demodulation in electrical capacitance tomography system

Electrical capacitance tomography (ECT) techniques have been developed to visualize industrial processes with dielectric materials. Phase-sensitive demodulator (PSD) is a crucial part in ECT system. Different methods of demodulation are demonstrated in this paper, including analogue and digital methods. Analogue demodulator can not overcome shortcomings of analogue devices which have been a bottleneck of imaging precision and speed. A digital demodulator based on FPGA and DSP is designed in this paper, and realizes the full digital quadrature demodulation. Both the systematic speed and precision are improved.

[1]  Wuqiang Yang,et al.  New AC-based capacitance tomography system , 1999 .

[2]  L Tarassenko,et al.  Impedance imaging in the newborn. , 1987, Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics.

[3]  B H Brown,et al.  The Sheffield data collection system. , 1987, Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics.

[4]  P J Riu,et al.  A broadband system for multifrequency static imaging in electrical impedance tomography. , 1992, Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics.

[5]  P H Sydenham,et al.  Phase sensitive detection as a means to recover signals buried in noise , 1975 .

[6]  G. Stefanini,et al.  Digital techniques applied to phase-sensitive detection , 1983 .