A New Time Domain Design Method of Cosine Modulated Filter Banks

The traditional cosine-modulated filter banks design method have some disadvantages, such as the necessary and sufficient conditions for a perfect reconstruction of the filter banks are strict, at the same time the nonlinear optimization algorithms fall down to local minimum easily and it's operation is complicated. A new method is proposed in this paper. The method can be used to improve modulation at first, the analysis filters are cosine-modulated and the synthesis filters are sine-modulated. Secondly the necessary and sufficient conditions for a perfect reconstruction are proved and the method of solving in time domain is also given. Finally a simpler time domain design method for the certain prototype filters is introduced. The theoretic and test results show that the conclusion is more universal, under the energy of the prototype filter is finitely. This new design method is very effective and useful because it does not require any nonlinear optimization.