Speech-amplifier telephone station
US4488007A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 16, 1982 |
| Grant date | Dec 11, 1984 |
| Priority date | — |
| Expiry date | Dec 16, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/08
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The telephone station has a first attenuator inserted in a transmission channel, and a second attenuator inserted in a reception channel. Each attenuator has a variable impedance mounted in shunt on the corresponding channel. A circuit controls the attenuators as a function of the relative levels of signals collected respectively from the transmission and reception channels. A bridge circuit introduces a difference between the levels of the signals collected respectively from the two channels. The bridge circuit includes a resistor bridge formed by two fixed resistors inserted in each channel upstream of the attenuator which is associated with said channel, and by a variable impedance which constitutes the attenuator. The common node of the two fixed resistors is the point of collection of the signal from each channel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.