学士学位论文___基于arm的电阻抗成像系统激励信号源设计.doc

毕业设计 题 目 激励信号源设计 学 院 专 业 二〇一三年月 电阻抗成像技术EIT是一种主要应用于医学检查的新兴的成像技术。它在物体表面通过电极或磁场施加电流或电压，经过物体内部后，再测量物体的电参数，应用重组算法计算电参数的分布，得到物体内部结构的图像。 本设计在分析研究国内外电阻抗断层成像技术现状基础上，了解了EIT的发展瓶颈和遇到的挑战。重点研究解决EIT的信号电源——恒流激励源，设计出基于DDS芯片的信号发生模块和以ARM处理器为控制核心的简易信号源。本设计中的信号源将EIT的信号源频带拓宽到了MHz以上。在高频下将能提取更丰富的复阻抗信息，为实现多频EIT技术提供了可能。 EIT激励信号源系统主要包括以下几部分：信号发生部分，包括采用DDS芯片组成的信号源硬件电路模块和VI转换电路模块；输出检测部分，用IO采集与正弦波同频率的方波来计数频率值，采用ARM自带的AD对电流值进行实测，然后将数据送给处理器显示；显示部分，采用128×64点阵式液晶显示屏实时显示设定值和频率电流实测值。 关键词: 电阻抗成像；多频恒流激励源；DDS；ARM应用 ABSTRACT Electrical impedance imaging technology （EIT） is a kind of the new imaging technology being mainly used in medical examination. It inject electric current or voltage through the electrode or the magnetic field on object surface, after internal objects, measuring electric parameters of the object, using restructuring algorithm to calculate electrical parameters of the distribution, to calculate the internal structure of the image. In the analysis of research on the basis of domestic electric impedance tomography imaging technology, This design understands the development bottleneck of EIT and the challenges. This design focus on the EIT signal power supply--constant current source.It makes out a signal source based on DDS chip module and the ARM processor. The Signal source of EIT in the design has a frequency band above the 1MHz.under the high frequency we will be able to extract more complex impedance information, in order to realize multi-frequency EIT technology. The EIT signal source system mainly includes the following several parts: signal part, including the use of DDS chip source hardware circuit module and the VI conversion circuit module; Output detection part, IO acquisition and sine wave with the frequency of square wave is used to count frequency values, using ARMs own AD to measurement of current value, and then send data to the processor; Display part, using the 128 * 64 dot-matrix LCD to