说明：  利用形态学方法，给ECG信号去基线漂移。基线漂移对心电影响很大。利用形态学上的腐蚀和膨胀，可以处理，但缺点是呈阶梯状，对原始信号有影响，这个是自己编的，未用matlab上的函数。
(Morphological method to the ECG signal to baseline drift. Baseline drift on the ECG. Morphological erosion and dilation can handle, but the drawback is that the ladder-like effect on the original signal, this is their own series of unused matlab function.)