摘要电阻抗断层成像是一种新兴的成像技术，目前主要应用于生物医学领域。该技术在生物体表面放置合适的电极，然后给生物体加载安全的电流。通过测量相关电极获得电压值，并将其与加载电流的信号值一同传输到电阻抗成像软件中。根据软件可以得到生物体内的电阻抗分布，进一步得到电阻抗断层图像，从而实现对生物体内部电阻抗信息的检测。该技术具有很多优点：采集信息无辐射、无需组织取样；硬件成本低；可实现连续监测。所以电阻抗断层成像是当今研究热点之一。33547
本论文研究了电阻抗断层成像的基本理论，重点阐述了基于电阻抗成像技术的数据采集系统的原理，探讨了电阻抗成像系统数据信息的采集与处理的关键技术；论证了适用于本论文的非均匀采样技术;设计并实现了基于FPGA的数字相敏解调器;对该数字相敏解调器进行了时序仿真并得出结论：该数字相敏解调器能够实现使低速模数转换器能够进行高采样率采样，减小模数转换器的量化误差，改善了信噪比。
关键词  电阻抗成像，相敏解调，非均匀采样，FPGA
毕业论文设计说明书中文摘要
毕业设计说明书外文摘要
Title   The reasearch of digital phase sensitive demodulator used in EIT system            
Abstract
Electrical impedance tomography is an emerging imaging technology, currently most used in the biomedical field. The technology places suitable electrodes on the organism surface and loads safe current into it .Put the voltage which is obtained by measuring the associated electrodes together with the loaded current signal into the electrical impedance tomography software .According to the software, the electrical impedance distribution of living body can be obtained.Also, electrical impedance tomography images can be obtained which can enable the detection of the electrical impedance information for the internal organism. The technology has no radiation,no tissue sampling.The low cost of it can achieve continuous detection. So electrical impedance tomography is one of the hot research today.
This paper studies the basic theories of electrical impedance tomography, focuses on the principle of the data acquisition system used in electrical impedance imaging technology,discusses the key technologies of acquiring data and processing  information in electrical impedance imaging system; proves a non-uniform sampling technique  which is applicable to this paper. The paper completes a digital phase sensitive demodulator based on FPGA , makes timing simulation of the digital phase sensitive demodulator and concludes: The digital phase sensitive demodulator enables low-speed ADC to achieve high rate sampling, reduces the ADC quantization error and improves the signal to noise ratio.
Keywords  EIT，non-uniform sampling，phase-sensitive demodulation，FPGA
目   录
1 绪论    1
1.1  电阻抗成像概述    1
1.1.1  电阻抗成像特点    1
1.1.2电阻抗成像方法    2
1.2 EIT技术国内外概况    2
1.2.1国外EIT的发展    2
1.2.2我国EIT研究进展    2
1.3  EIT技术应用前景及难点    3
1.4  本论文的主要内容    3
2  EIT技术的工作原理    5
2.1 EIT技术的生物学基础    5
2.2 EIT的图像重建    6
3 EIT技术的数据采集与处理    8
3.1 驱动模式    8
3.2数字相敏解调技术    9
3.2.1 Fourier算法    9
3.2.2非均匀采样技术    12 FPGA应用于EIT系统的数字相敏解调器的研究:http://www.751com.cn/tongxin/lunwen_30709.html