Design of M-channel linear-phase non-uniform filter banks with arbitrary rational sampling factors

摘要

The majority of the existing work on designing non-uniform filter banks (NUFBs) cannot realise arbitrary rational frequency partitioning, due to the ineliminable large aliasing caused by the non-feasible permutation of rational sampling factors. In this study, the authors extend the efficient modulation technique to non-feasible partitioned NUFBs and then generalise the phase modification structure to the case of rational decimators to achieve the linear-phase (LP) property. Through a step-by-step analysis on the aliasing elimination of both feasible and non-feasible subbands, it is proved that when the symmetry of filters and phase modification factors are chosen to meet the derived matching conditions, the non-LP characteristic of shifted filters can be transferred to LP one and further the non-feasible partitioned NUFB is obtained with highly desired LP property. Compared with the existing typical NUFB designs, the proposed approach can achieve comparable performance with much lower system delay and implementation complexity.