基于MIT软件鉴相系统设计和相位检测实验

Design of Improved MIT Software Phase Detection Unit and Experiments

为解决脑磁感应成像(MIT)系统中相位差检测问题,改进并实现了MIT软件鉴相平台。软件部分采用LabVIEW2009,相位差检测选用FFT鉴相算法;硬件部分选用NI PXI 5122采集卡对数据进行100 MS.s-1的实时采样,选用考虑电磁安全性的增益放大模块实现对微弱小信号的功率放大。构建了一套采样精度高、放大增益可调、基于FFT算法的MIT软件鉴相平台。在模拟脑出血实验中进行相位差检测,随着出血量的增加,相位差相应增大;激励信号功率一定时,随着激励频率增大相位差增大。鉴相精度在原0.01°的基础上提高到0.001°;能够更好地测量和反映MIT系统中组织电导率的变化。

In order to solve the phase difference detection in brain magnetic imaging（MIT） systems,we improve and achieve a phase MIT software platform.Software is LabVIEW2009,and phase detection uses FFT phase detection algorithm;hardware is the NI PXI 5122 data acquisition card of 100 MS·s-1 real-time sampling,and consider the use of electromagnetic security module for the weak gain amplification of small signal amplification.A sampling of high precision,adjustable amplification gain,FFT-based algorithm phase MIT software platform is built.In the simulation experiments of Cerebral hemorrhage phase detection,phase difference increases with the amount of bleeding;and with constant excitation signal power,the phase difference increases with excitation frequency.Phase accuracy improves from the original 0.01 degrees to 0.001 degrees,which indicates that the MIT system could better reflect changes in tissue conductivity.