welch

说明：  本程序实现了短数据序列不同窗函数的welch功率谱估计，然后又求了他们的平均标准差，从而判断各个窗函数的优劣。只要稍作修改就能实现不同信噪比下的功率估计，同时也可以实现长数据序列的估计。(This procedure has a short data series of different welch window function power spectrum estimation, and then seek their average standard deviation, and thus to determine the merits and demerits of each window function. As long as we can with some slight modifications under different signal to noise ratio power estimate, but also the realization of a long data sequence can be estimated.)