Digital tone control with linear step coefficients
US6892103B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 27, 1999 |
| Grant date | May 10, 2005 |
| Priority date | — |
| Expiry date | Sep 27, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G5/005
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Digital audio tone control implemented using Shelving filters for the digital audio treble tone control exhibits artifacts (noise, distortion, etc.) as the tone control settings are changed. This was previously accomplished by changing filter coefficients in the traditional small equal (on a dB scale) filter steps of a fraction of 1 dB. While this worked for bass filters, artifacts were still present for treble. This invention eliminates these artifacts by changing the filter steps to small equal steps on a linear scale. Additionally, where the steps became too large for the resolution required, additional filter steps are added. Approximately 150 filter steps are used for treble control and 128 filter steps are used for bass tone control. An efficient way of implementing the filter steps for digital tone control stores (119) one set of filter coefficient values and a small amount of additional information and then increments the coefficients between all the other steps. This reduces the memory required by as much as 95% or the machine cycles for implementing filter coefficients by 40-200 times. This new efficient method is accomplished by: 1) defining the filter coefficients, 2) p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.