Miniature bridge lifter for telephone lines
US4166931A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 24, 1978 |
| Grant date | Sep 4, 1979 |
| Priority date | — |
| Expiry date | Apr 24, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q5/02
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A miniature electronic bridge lifter for bridged telephone lines which can be mounted directly on the protector unit in the central office includes an impedance inserted serially in each side of the loop for isolating the nonactive loops from the central office termination and for switching to a low impedance connection whenever a party on one of the bridged line connections goes off-hook. A combination semiconductive and resistive voltage divider detects the voltage across the loop. The resistive component is essentially the only cross-coupling between the telephone lines. When the line voltage falls below a preselected threshold, indicating that the connected party has gone off-hook, a switch is operated to bypass the series impedances and establish a low-loss path to the common line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.