Universal channel unit switchable between two wire and four wire configurations
US5034978A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 1989 |
| Grant date | Jul 23, 1991 |
| Priority date | — |
| Expiry date | Dec 15, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/586
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The universal channel unit includes a channel interface circuit that uses a pair of fixed ratio transformers to terminate both two wire and four wire analog transmission facilities on a selectable basis. The universal channel unit also includes a plurality of signalling circuits, each of which is switchably connectable via the channel interface unit to provide a DC signalling interface to match the signalling format required by the associated analog transmission facility. The signalling circuits include: DX, FXO, FXS, and other DC signalling circuits. The AC component of the signals carried by the analog transmission facility is output to an adaptive impedance and balance circuit which functions to closely match the impedance of the analog transmission facility and minimize signal reflections under control of a microprocessor. This impedance and balance network is connected to a PCM interface that includes an adaptive echo canceller circuit as well as equalization and gain control circuits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.