正交镜像滤波器的设计，从正交镜像滤波器的远离出发设计,而且从结果中观察其相位和幅度。- Design a two-channel QMF filter bank

The four filters in the filter bank are based on a lowpass prototype H(z)

which is designed by this procedure. The analysis filters are HL(z) and

HH(z) and the synthesis filters are GL(z) and GH(z),

　 HL(z) = H(z)　　　 HH(z) = H(-z)

　 GL(z) = 2 H(z)　　 GH(z) =-2 H(-z