A Digital Switching Demodulator for Electrical Capacitance Tomography
A Digital Switching Demodulator for Electrical Capacitance Tomography
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DOI：
10.1109/tim.2012.2236731
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发表时间：
2013-02
影响因子：
5.6
通讯作者：
Lijun Xu;Haili Zhou;Z. Cao;Wuqiang Yang
中科院分区：
文献类型：
--
作者：
Lijun Xu;Haili Zhou;Z. Cao;Wuqiang Yang
在本文中，提出了一种用于基于交流的电容层析成像系统的数字开关解调器。以数字方式实现开关相敏解调器（PSD）具有以下优点： 1）可以使用可编程数字器件来实现解调，因此不再需要传统开关PSD中使用的CMOS开关； 2）与广泛使用的数字正交PSD相比，该解调器配置简单，因为不需要参考信号，也不需要乘法； 3)根据具体要求，新型解调器可以实现幅值模式和相敏模式两种工作模式； 4)因为只需要减法和累加，所以所提出的解调器可以很容易地用低成本逻辑器件(例如复杂可编程逻辑器件(CPLD))来实现。通过仿真，证实了所提出的解调器的可行性和有效性。构建了基于CPLD和基于现场可编程门阵列的电容测量电路，并比较了不同解调方法的性能。仿真和实验均表明，所提出的解调器能够提供高信噪比的解调结果。使用数字开关解调器可以简化系统设计。
In this paper, a digital switching demodulator is presented for use in ac-based electrical capacitance tomography systems. Implementing a switching phase-sensitive demodulator (PSD) digitally offers the following advantages: 1) Demodulation can be implemented using a programmable digital device, and hence, CMOS switches, which are used in a conventional switching PSD, are no longer needed; 2) compared with the widely used digital quadrature PSD, this proposed demodulator is simple in configuration because neither a reference signal nor multiplication is required; 3) according to the specific requirements, the new demodulator can be implemented in two operation modes, i.e., the amplitude mode and the phase-sensitive mode; and 4) because only subtractions and accumulations are needed, the proposed demodulator can be easily implemented with low-cost logic devices, e.g., a complex programmable logic device (CPLD). By simulation, the feasibility and effectiveness of the proposed demodulator have been confirmed. CPLD-based and field-programmable-gate-array-based capacitance measurement circuits are constructed, and the performances of different demodulation methods are compared. Both simulation and experiment show that the proposed demodulator can provide demodulation results with high signal-to-noise ratio. The system design can be simplified using the digital switching demodulator.