Telephone line circuit and system
US4456991A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 10, 1983 |
| Grant date | Jun 26, 1984 |
| Priority date | — |
| Expiry date | Jan 10, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q11/04
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A telephone line circuit and system for interfacing digital exchange line circuits to a terminal interface of a switching network is disclosed. The system includes controllable active circuit impedance matching means for reducing impedance mismatch between a selected line circuit and the terminal interface. Control means controls both the active circuit impedance matching means for adjusting the effective circuit impedance to a value within a predetermined range, and the conditioning circuit gain pads for selectably adjusting the gain of a transmitted signal. Additionally, control means controls the d.c. line impedance and voltage for adjusting the effective line feed current to the subscriber loop, and provides interfaces for a plurality of line circuits to both a switching network and external processor. Supervision means provides supervision control signals to the control means and thereby permits the telephone line circuit system to provide desired telephone system functions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.