平均周期法计算 fft的结果，Bartlett平均周期图的方法是将N点的有限长序列x(n)分段求周期图再平均，Welch法对Bartlett法进行了两方面的修正...

平均周期法计算 fft的结果，Bartlett平均周期图的方法是将N点的有限长序列x(n)分段求周期图再平均，Welch法对Bartlett法进行了两方面的修正，一是选择适当的窗函数w(n)，并再周期图计算前直接加进去，加窗的优点是无论什么样的窗函数均可使谱估计非负。二是在分段时，可使各段之间有重叠，这样会使方差减小。 -The average cycle method to calculate the fft results, Bartlett average periodogram method is limited to N-point long sequence x (n) Sub-seeking re-average periodogram, Welch method of Bartlett law was amended in two areas, first select the appropriate The window function w (n), and re-cycle before CALPHAD directly incorporated, plus the advantage of a window no matter what kind of window function will be to make spectrum estimation of non-negative. Second, in sub-paragraph, the can have overlap between the paragraphs, it may lead to variance reduction.