瞬态信号高分辨力谱分析——富里叶变换插值法

在介绍提高谱线分辨力的2种数字处理方法(BSFA和移频低通滤波)的基础上,根据谱线间隔Δf=1/(NΔ),要提高谱线分辨力,不仅增大Δ,增大N同样也可以降低Δf,提出了富里叶交换(FFT)插值法。但N值的增大不是由原始采样数据补充零来实现,而是根据在频谱图上选取感兴趣的频域范围作为富氏变换的输入,将谱线的谱添加若干零后再作反富氏变换,得到放大2倍的谱线。该方法在多组信号相关谱分析中尤其适用。 

ANALYSIS OF HIGH RESOLUTION SPECTRA OF TRANSIENT SIGNALS-THE FFT INTERPOLATION METHOD

Now, there are two methods to improve the spectral resolution, which are the Band Selected Fourier Analysis and the Digtal Frequency Moving Lower Pass. But on the formulation Δf=1/(NΔ)(N is-sampling data number, Δ is the sampling time interval), increasing Δ can reduce the spectral resolution Δf, increasing N can cut dow Δf too. This paper introduces a new method that does not increase the sampling data number N, but selects the frequency range on the spectral, which is interested, as the input of FFT. the output of FFT is added zeros as the inverse FFT's input, the result is the spectral that is amplified two times. We can obtaine any times amplified spectral by using process above. This method will be found widely use in the correlation spectral analysis of several signals.