Aliasing reduction using complex-exponential modulated filterbanks
US7242710B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 2, 2002 |
| Grant date | Jul 10, 2007 |
| Priority date | — |
| Expiry date | Jan 9, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H17/0266
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The present invention proposes a new method and apparatus for the improvement of digital filterbanks, by a complex extension of cosine modulated digital filterbanks. The invention employs complex-exponential modulation of a low-pass prototype filter and a new method for optimizing the characteristics of this filter. The invention substantially reduces artifacts due to aliasing emerging from independent modifications of subband signals, for example when using a filterbank as an spectral equalizer. The invention is preferably implemented in software, running on a standard PC or a digital signal processor (DSP), but can also be hardcoded on a custom chip. The invention offers essential improvements for various types of digital equalizers, adaptive filters, multiband companders and spectral envelope adjusting filterbanks used in high frequency reconstruction (HFR) systems.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.