fMRI扫描噪声有源控制系统的次级通道建模

The secondary path modeling for f MRI scanning noise active control system

目的采用一种附加高斯白噪声的次级通道离线建模方法,来获取有源主动降噪系统次级通道传递函数估计值。材料与方法利用LabVIEW FPGA终端来设计噪声采集程序,将采集的信号送给上位机,在上位机实现次级通道建模,然后利用次级通道传递函数的估计值,完成对有源噪声控制系统的仿真,并分析了仿真的结果。结果建立了次级通道的参数模型,最终在有源噪声控制系统仿真的过程中,可以取得19 dB(与原噪声幅值相比)左右的降噪效果。结论基于LabVIEW开发环境,实现了次级通道离线建模和有源噪声控制系统的仿真实验,为接下来进一步实现噪声的实时控制,搭建了一个很好的平台。

Objective： An additive gaussian white noise off-line modeling method is proposed for estimating the transfer function of secondary path. Materials and Methods： The acquisition program is implemented based on LabVIEW FPGA terminal. Then the acquired signal is transmitted to the host computer where the secondary path modeling program is achieved. Finally,the active noise control system simulation program is developed relying on the estimated parameters of the secondary path transfer function during the running of simulation program in the host computer. Results： The estimation of the secondary path transfer function is acquired. Finally around 19 dB（compared with primary noise） noise reduction can be achieved in the simulation of the active noise control system. Conclusions： The secondary path modeling and the active noise control system simulation program are accomplished based on LabVIEW software,which provides a good platform for the noise of realtime controlling.