摘要
目的 研制用于电阻抗参数成像数据采集系统的信号源 .方法 基于直接数字合成技术 ,以扫频和混频相结合的方式建立了具有 4种工作模式、最多可同时输出 4种频率成分的信号源 .结果 信号源的输出频率可以在 1.6～ 380k Hz的频带范围内以小于 10 0 Hz的跨度编程选择 ,输出的噪声水平在 - 80 d B左右 ,信噪比大于 6 0 d B.结论 用多频率组合与扫频相结合的方式可以灵活地改变测量频率 ,控制信号的精度及测量的速度 ,为高质量的数据采集提供了保障 .
AIM To develop a signal source for data collection system of electrical impedance parameter tomography. METHODS Based on direct digital synthetic technique, sweeping frequency technique combined with mixing fre quency technique was employed to establish the signal source. This signal source has four output modes and the maximum output frequency number is four. RESULTS The frequency range of signal source is 1.6~380 kHz. The minimum frequency interval between any two frequencies is less than 100 Hz. The noise level of output is about -80 dB, and the signal to noise ratio is up to 60 dB. CONCLUSION By combining sweeping frequency technique with mixing frequency technique, the measure flexibly frequency can be selected. And the signal precision as well as the measuring speed can also be controlled easily. These make it possible for high quality data to be acquired in electrical impedance parameter tomography.
出处
《第四军医大学学报》
2000年第11期1367-1370,共4页
Journal of the Fourth Military Medical University
基金
国家自然科学基金资助项目(39870217)
“九五”国家重点攻关课题(96-920-12-04)
关键词
电阻抗断层成像
阻抗参数
数据采集
直接数字合成
electrical impedance tomography
impedance parameter
data collection
direct digital synthesize
