ADPCM Encoder/decoder with signalling bit insertion
US4549304A · kind A · utility
13Cited by
5References
5Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 28, 1983 |
| Grant date | Oct 22, 1985 |
| Priority date | — |
| Expiry date | Nov 28, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B14/068
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In an ADPCM transmission system, signalling frames of an incoming multiplexed PCM signal are identified and signalling bits extracted therefrom. During each signalling frame, an ADPCM encoder/decoder is controlled by the signalling frame signal to operate entirely for 3-bit ADPCM, instead of the regular 4-bit ADPCM, to which 3-bit ADPCM the extracted signalling bits are added for transmission. The deliberate alteration from 4-bit to 3-bit ADPCM at the encoder and decoder of the system in each signalling frame ensures proper adaptation and consequently no loss of tracking between the encoder and the decoder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.