说明： 信号采样，可以是临界采样，也可以是过采样，还可以是欠采样，不同的采样导致不同的恢复效果，本代码将展示不同之处。 (Signal sampling, the sampling can be critical, it can be over-sampling, can also be due to sampling, different sampling led to the recovery of the different effects, the code will show the difference.)
