在每一次小波变换中，都提取其中的“逼近信号”作为下次变换的输入，同时忽略掉其中的“细节信号”，即清除一次信号中包含的高频噪声分量。变换后的输出信号与原始信号相比，噪声起伏明显改善。-In every wavelet transform are extracted one of the " approximation signal"　as the input of the next change, while ignoring one of the " details of the signal" , that is, a clear signal contains high frequency noise components. Transformed output signal compared with the original signal and noise fluctuations significantly improved.