说明：   一般来说，瞬时频率和群延迟在时频平面内定义了两条不同的曲线，但是在时宽（T）和频宽（B）的乘积值逐渐变大时，这两条曲线会慢慢逼近。为了说明这一点，下面计算了信号的瞬时频率和群延迟，T*B值小。
( In general, the instantaneous frequency and group delay in the time-frequency plane defines two different curves, but when the width [T] and bandwidth [B] the product of value become bigger, the two curves will be slow slow approximation. To illustrate this point, the following calculation of the signal instantaneous frequency and group delay, T* B value small.)