Electronic telephone system with time division multiplexed signalling
US4211895A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 1977 |
| Grant date | Jul 8, 1980 |
| Priority date | — |
| Expiry date | Dec 5, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q3/521
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An electronic telephone system has a plurality of extensions connected radially to a central equipment by respective cables each providing separate speech and signalling paths. Each of the signalling paths is provided by a balanced conductor pair terminated by a matching impedance at the extension unit. The conductor pairs are connected to a common control unit at the central equipment, which scans the extensions in a time-division multiplex mode, signalling data being transmitted over the conductor pair from the addressed extension to the control unit in a first period of the time slot allotted to the extension, and signalling data being transmitted from the control unit to the addressed extension in a second period of the allotted time slot. The system is also served by a number of trunks, which are scanned by the common control unit, the trunks being interfaced with the central equipment by interface units which include protective circuitry and logic control circuits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.