Least-squares design of subsampled allpass transformed DFT filter-banks with LTI property

A new design approach for an allpass transformed analysis-synthesis filter-bank (AS FB) with subsampling is proposed, which can be used for adaptive subband processing with non-uniform timefrequency resolution. Signal reconstruction is performed by an FIR synthesis filter-bank whose coefficients are determined by two different linear least-squares (LS) error designs. The presented unconstrained LS optimization leads to perfect reconstruction (PR), but an insufficient bandpass characteristic for the synthesis subband filters. This problem is solved by a second, equality constrained least-squares (CLS) error design, which achieves near-perfect reconstruction (NPR). In the process, the linear distortions are minimized with the constraint for a linear, time-invariant (LTI) overall transfer function. The aliasing-free reconstruction error is significantly lower than for known designs of allpass transformed DFT filter-banks with NPR. Moreover, the new filter-bank design allows for a...

• Type: Conference
• Year: 2008
• Where: ICASSP
• Authors: Heinrich W. Löllmann, Guido Dartmann, Peter Vary
• Keywords: Aliasing-free Reconstruction Error, Allpass Transformed Analysis-synthesis, Error Design, ICASSP 2008, Signal Processing