Transmission system for coded speech signals and/or voiceband data
US5615297A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 10, 1994 |
| Grant date | Mar 25, 1997 |
| Priority date | — |
| Expiry date | Jun 10, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/068
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A digital coder receives either speech or audio-band data. When receiving speech this is coded by a digital speech coder and formatted into frames with parity bits. If modulated data are present this is recognized by a detector which routes the signals instead via a demodulator. Parity bits are generated from the same frame portions but parity is inverted so that a parity checking unit at a receiver can readily recognise the change. Preferably means are provided to insert into data frames codewords identifying the start and end and indicating the type of modulation in use. Additional detectors and demodulators can be added for different types of modulation. Such coded signals are decoded by performing parity checks on received frames to produce a parity indication signal of a first data mode sense or a second speech mode sense. In a data mode, the received signals modulated in accordance with a predetermined modulation scheme are provided as an output and in a speech mode the received signals are decoded to provide a speech output.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.