说明：  S变换是较新的时频分析工具，甩在低频段有较宽的的时间窗，以获得较高的频率分辨率；而在高频段时间窗窄，以获得较高的时间分辨率。这里给出了ST和GST（广义S变换）的函数。
(S transform is a relatively new time-frequency analysis tool, left in the low frequency band has a wide time window in order to obtain higher frequency resolution and in high-frequency narrow time window in order to obtain higher temporal resolution. Here are given ST and GST (generalized S transform) function.)