生物电阻抗特征参数测量数据采集系统的研究

为了实现生物电阻抗参数成像，我们建立了一个快速、精确的生物电阻抗特性参数测量的数据采集系统，采取多频率组合激励并扫基频的方法，在多个激励频率不同测量阻抗信息，同时采用了一种新的高精度解调方法；正交序列数字解调，并对阻抗模型参数的估算方法进行了改进。结果表明，系统可以在1．6kHz-380kHz的频带范围内以小于100Hz的跨度编程选择工作频率，最多时可同时在四种频率下测量阻抗信息，系统的噪声水平在－80dB左右。在每周期采样64点的情况下，解调算法可将信噪比提高5．6倍以上。

STUDY ON A DATA ACQUISITION SYSTEM FOR BIO-ELECTRICAL IMPEDANCE PARAMETERS MEASUREMENT

In order to establish electrical impedance parameter tomography (EIPT),we have accomplished a rapid, precise acquisition system for bio-electrical impedance characteristic parameters measurement, and the sweeping frequency technique combined with mixing frequency technique, which can collect impedance information at different frequencies simultaneously, was employed. Also, a new demodulation method, named by us as “orthogonal sequential digital demodulation”, was chosen to improve system precision. The results showed that this system could select frequencies from 1.6kHz to 380kHz with a minimum frequency interval between any two frequencies less than 100Hz. It could collect impedance information at four different frequencies at the same time. The noise level of the signal source was about -80DB. And if 64 points per period was sampled, the signal to noise ratio could be improved by more then 5.6 times by demodulate algorithm.