The corresponding WPD entropy values increase sharply when discrete spectrum interference (DSI), frequency spectrum of which is centered by several frequency points, exists in some frequency region.

• 将信号的小波包变换看做通过等带宽的滤波器组,输出是对应频带上的分量,如某一频带上存在离散谱干扰,其小波包变换树节点的信息熵将会明显增大。