engleski

A systematic technique for designing prototype filters for perfect-reconstruction cosine-modulated and modified DFT filter banks

Optimizing the angles for the lattice structures in the prototype filter for perfect-reconstruction cosine-modulated and modified DFT filter banks is a very difficult task because there exist sev-eral local optima. In order to get around this problem, this paper describes an efficient systematic technique for designing proto-type filters in the least-mean-square sense. First, the few angles for the two-channel case are optimized using various techniques for numerous filter lengths and stop-band edge frequencies. The resulting angles are expressed as polynomials of the stop-band edge for later use. After knowing the angles for the two-channel case, corresponding filter banks having several channels can be effectively generated by gradually increasing the number of channels and by properly using the result of the previous step as a start-up solution for the present step. This approach allows us to design very fast at least good locally optimized prototype fil-ters for banks having many channels and long channel filters.

filter banks; cosine modulated; perfect reconstruction

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