说明：  本程序先生成一个“Blocks”信号，然后加上高斯白噪声，再用 db3 小波进行分解， 以说明三种取阈值方法和三种噪声标志对去噪性能的影响。
(This procedure Mr. Cheng a " Blocks" signal, and then adding white Gaussian noise, and then ' db3' wavelet decomposition, to illustrate the three kinds of check-threshold method and three kinds of noise, signs of de-noising performance.)