用matlab仿真，研究不同阈值降噪后的效果，使用penalty阙值降噪后信号，使用Birge_Massart阙值降噪后信号，使用缺省阙值降噪后信号。-Using matlab simulation to study the different threshold noise reduction effect, the use of penalty threshold denoised signal after noise reduction using Birge_Massart thresh