摘要
研究了基于带宽估计多普勒夹角平均时相选择、多普勒带宽的计算、信号频谱的估计方法等问题,提出了一种新方法:先对多普勒信号进行基于主元分析的降噪,然后使用短时傅里叶变换(STFT)进行夹角估计,最后在收缩后期进行平均.通过颈动脉超声多普勒信号的计算机仿真实验,得出:夹角平均应选在收缩后期;STFT估计夹角应用fmean,AR模型估计夹角用fmean和fp均可;STFT和AR模型在估计夹角的性能各有优劣.新方法较大程度地改善了多普勒夹角估计方法的抗噪声性能,可以在信噪比较低的情况下使用.
Three problems are studied in order to improve the performance of the Doppler angle estimation method based on the spectral bandwidth. They are the choice of the cardiac phase over which estimated angle result should be averaged,the calculation of the Doppler bandwidth and the estimation of the signal spectrum. A novel method is proposed in which the principal component analysis (PCA) is firstly used to de-noising signals,the angle is then estimated with the short fime Fourier transform(STFT),the average result is finally got over the anaphase of the systole. From the computer simulation experiments of carotid Doppler signals,it is foud that angles should be averaged over the anaphase of systole.In STFT method,the Doppler bandwith is well estimated using the mean frequency while either the mean frequency or the peak frequency can be used in AR modeling method. It is also seen that both STFT and AR modeling methods have advantage and disadvantage over each other in the Doppler angle estimation.With the proposed method,the anti-noise performance is greatly improved,which means that it is useful under the low Signal-to-Noise-Ratio(SNR) condition.
出处
《复旦学报（自然科学版）》
CAS
CSCD
北大核心
2005年第1期51-55,共5页
Journal of Fudan University：Natural Science
基金
上海市曙光计划资助项目(20030901)
