Pulse code modulation compression mechanism
US5883925A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 16, 1995 |
| Grant date | Mar 16, 1999 |
| Priority date | — |
| Expiry date | Nov 16, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/66
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A pulse code modulation (PCM) unit is connected to a bus in a computer system. Also, connected to the bus is a processor and memory. The PCM unit is connected to transmit and receive telephone lines. The PCM unit reads uncompressed PCM data from the memory over the bus and compresses the PCM data for transmission over the telephone line in a cycle steal operation, wherein the bus is not being used by the processor. The PCM receives compressed PCM data from the receive telephone line, decompresses it, and writes the decompressed PCM data to the memory in a cycle steal operation. In addition, selectivity of either .mu.-Law or A-Law conversion, selectivity of even bit inversion for A-Law conversion, and selectivity between the compressed/decompressed PCM data or raw data is provided on a per channel basis. Selectable linear gain is also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.