摘要
本文设计了一种基于DSP的主从式人体电阻抗断层成像系统,频率范围从10kHz到1MHz。系统采用PC机作为主控机,DSP控制激励信号、电极选通、数据采集并与上位机通讯。采用直接数字合成(DDS)技术构建正弦波发生器,加入反馈环节,有效提高了压控电流源的线性度和稳定性;采用低导通电阻的多路开关;基于测量有效值和相位差实现相敏解调,获取人体复阻抗信息;采用16位AD转换器,提高测量信号的分辨率。试验测试与成像结果表明,该系统能够在较宽的频带范围保证测量精度和图像分辨率。
A master-slave Electrical Impedance DSP is designed in this paper. The frequency covers Tomography system for body complex impedance based on the range from 10kHz to 1MHz. A PC is used as a master computer, which performs the image reconstruction and display on time, while DSP carries out the tasks, such as e- lectrode selection, data acquisition and data communication with the master. Some methods were taken to improve the measurement accuracy. Based on DDS technique and with a feedback unit, the voltage-controlled current source has the perfect linearity and stability. The multiplexers with very low on-resistance are used; To achieve the body complex impedance information, a novel phase sensitive demodulation circuit is adopted through measuring the RMS and phase of the signal. A 16 bit AD converter is used to improve the resolution. Experimental results show that this system improved the data acquisition precision and the image resolution in a wider frequency range.
出处
《电子测量与仪器学报》
CSCD
2006年第2期48-51,共4页
Journal of Electronic Measurement and Instrumentation
基金
国家自然科学基金资助项目(编号:60472077
50337020
60301008)
河南省自然科学基金资助项目(编号:0511012100)。
关键词
电阻抗断层成像
EIT
直接数字信号合成(DDS)
相敏解调
复阻抗信息
EIT（ Electrical Impedance Tomography）, complex impedance information. phase sensitive demodulation, direct digital synthesis,
