Digital-to-digital conversion using non-uniform sample rates
US5497152A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 11, 1994 |
| Grant date | Mar 5, 1996 |
| Priority date | — |
| Expiry date | May 11, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L2207/50
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for digital-to-digital 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 noise produced by non-uniform sampling are frequency-shaped to a region (i.e., shifted to higher frequencies) where it can be removed by conventional filtering techniques. In one embodiment, the digital data is interpolated by 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. Thereafter, the digital data is interpolated under control of a sigma-delta modulated frequency selection signal that represents, on average, the data rate of the digital data to be output by the converter and then decimated by a fixed ratio. The first and second frequency signal selection numbers are modulated using n-th order m-bit sigma-delta modulators. The method and apparatus converts the data rate of the incoming digital data stream to the data rate of the first n-th m-bit sigma-delta modulator and then converts the digital data stre…
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