in the Noble identify of Analysis/Synthesis filter banks,
there are two Z functions : H(Z) and H(Z^m).
And the H(Z^m) should be a low pass filter. Then I found it was difficult to impement H(Z) if H(Z^m) is an ordinary low pass filter.
So I think if H(Z^m) = b0 + b1*Z^(-32) + b2*Z^(-64) + b3*Z^(-96) + .......... + bn*Z^(-n*32) (1)
The H(Z) can be easiy to be implemented.

But I have no idea to design a filter whose coefficients have the property of formulation (1).

do you have any ideas ?


if you are interesting in this topic, my MSN: zzy@hotmail.it

This is covered fairly well in most textbooks. I recommend starting with the section on polyphase filters in Oppenheim and Schafer, which will answer your question.