ADPCM encoder/decoder with improved tracking
US4592070A · kind A · utility
25Cited by
5References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 28, 1983 |
| Grant date | May 27, 1986 |
| Priority date | — |
| Expiry date | Nov 28, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/042
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An ADPCM encoder and decoder includes an adaptive quantizer and an adaptive predictor. A quantizing-step-size adaptation circuit determines a quantizing-step-size for the adaptive quantizer in dependence upon the ADPCM signal. When the quantizing-step-size is small, updating of predictor coefficients, produced in the adaptive predictor, in dependence upon a reconstructed signal and a reconstructed error signal derived from the ADPCM signal, is inhibited, the predictor coefficients being updated only in dependence upon a leakage function. This enables improved tracking to be achieved by the ADPCM arrangement.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.