IMPROVED DESIGN OF OVERSAMPLED ALLPASS TRANSFORMED DFTFILTER-BANKS WITH NEAR-PERFECT RECONSTRUCTION

摘要

In this paper, the design of oversampled allpass transformedrnanalysis-synthesis filter-banks is treated, which can be em-rnployed for non-uniform subband processing. Near-perfectrnreconstruction can be achieved by a synthesis filter-bank de-rnsign which uses phase equalizers to compensate the phasernmodifications due to the allpass transformation of the ana-rnlysis filter-bank. It is shown that an FIR phase equalizer,rnwhich is obtained by a least-squares approximation of therndesired non-causal IIR phase equalizer, leads to almost per-rnfect signal reconstruction and causes only a comparativelyrnlow signal delay. The devised synthesis filter-bank designrncan be described by a closed-form expression and allows torncontrol the trade-off between reconstruction errors on thernone hand and signal delay and computational complexity onrnthe other hand.