Xie Taorong, Pei Jian, Jia Caili, Chen Shude, Qiao Dengjiang
State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2009 Aug;26(4):743-7.
It is very important to extract electroencephalogram (EEG) rhythm in clinical diagnoses. Digital filter and wavelet transform are used to extract the rhythm from a piece of EEG at the sampling rate of 2 kHz. The Daubechies order 4 wavelet (db4) was used to decompose the EEG at 8 levels. According to the filter characteristic of wavelet decomposition, the reconstructions of aS, d8, d7, d6 and d5 component are nearly corresponding to the rhythms of delta, theta, alpha, gamma separately. The 6 order ellipse infinite impulse response (IIR) filter is also used to decompose the EEG. As the quality factor of wavelet decomposition filter is constant, the wavelet transform obtains better extracted rhythm than the digital filter. Furthermore, the wavelet transform method can be used to extract the low frequency rhythm from wide frequency band.
在临床诊断中提取脑电图（EEG）节律非常重要。数字滤波器和小波变换被用于以2kHz的采样率从一段脑电图中提取节律。采用Daubechies 4阶小波（db4）对脑电图进行8层分解。根据小波分解的滤波器特性，aS、d8、d7、d6和d5分量的重构分别近似对应于δ、θ、α、γ节律。还使用6阶椭圆无限脉冲响应（IIR）滤波器对脑电图进行分解。由于小波分解滤波器的品质因数是恒定的，小波变换比数字滤波器能获得更好的节律提取效果。此外，小波变换方法可用于从宽频带中提取低频节律。
