Design of Multiple Order Allpass Transformed DFT Filter-Banks with Aliasing-Free Signal Reconstruction by Linear Programming
Conference: Sprachkommunikation 2008 - 8. ITG-Fachtagung
10/08/2008 - 10/10/2008 at Aachen, Germany
Proceedings: Sprachkommunikation 2008
Pages: 4Language: englishTyp: PDFPersonal VDE Members are entitled to a 10% discount on this title
Löllmann, Heinrich W.; Vary, Peter (Institute of Communication Systems and Data Processing, RWTH Aachen University, 52056 Aachen)
Dartmann, Guido (Institute for Integrated Signal Processing Systems (ISS), RWTH Aachen University, 52056 Aachen)
The allpass transformation of multiple order is a very general approach to design a frequency warped analysis-synthesis filter-bank (AS FB) with non-uniform timefrequency resolution. In the design process, the delay elements of the analysis filter-bank are substituted by allpass filters of higher order to achieve a very flexible control over its frequency selectivity. Analytical closed-form designs for the synthesis filter-bank can ensure perfect reconstruction (PR), but the synthesis subband filters are not necessarily stable or exhibit a bandpass characteristic. We tackle these problems by a constrained leastsquares error (CLS) design. The coefficients of the new synthesis filter-bank are determined by a linear set of equations with linear constraints. The resulting synthesis filters are stable and exhibit a distinctive bandpass characteristic. Our design by linear programming can achieve an aliasingfree, near-perfect signal reconstruction, where the signal delay is an adjustable design parameter. These properties make the proposed filter-bank of interest for subband processing systems requiring non-uniform frequency bands.