Digital to analog conversion using non-uniform sample rates
US5489903A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 17, 1995 |
| Grant date | Feb 6, 1996 |
| Priority date | — |
| Expiry date | Jan 17, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/50
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for digital to analog conversion using sigma-delta modulation of the temporal spacing between digital samples. The method and apparatus of the present invention provides for sigma-delta modulation of the time base such that errors produced by non-uniform sampling are frequency-shaped to a region (i.e., shifted to higher frequencies) where they can be removed by conventional filtering techniques. In one embodiment, the digital data is interpolated by a fixed ratio and then decimated under control of a sigma-delta modulated frequency selection signal that represents, on average, the data rate of the incoming digital data stream. The frequency signal selection number is modulated using an n-th order m-bit sigma-delta modulator. Data thus emerges from the interpolation/decimation process at the clock rate of the n-th order m-bit sigma-delta modulator. The method and apparatus converts the data rate of the incoming digital data stream to the data rate of the n-th order m-bit sigma-delta modulator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.