Design of allpass-based non-uniform oversampled DFT filter banks
In this paper we address design and properties of an oversampled non-uniform DFT filter bank derived by an allpass frequency transform from its uniform version. The novel synthesis bank utilizes only stable FIR filters, which can be designed via closed-form expressions. The overall analysis-synthesis system leads to a near-perfect-reconstruction solution, where the phase compensation error can be made arbitrarily small at the expense of additional system delay. Furthermore, we also address the case of different sub-sampling factors in the subbands. The filter bank design is carried out by utilizing a lifting factorization for the prototypes, which has the advantage that the overall system delay can be controlled in an efficient way.