Speakerphone controlled by a comparator with hysteresis
US5692042A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 31, 1995 |
| Grant date | Nov 25, 1997 |
| Priority date | — |
| Expiry date | May 31, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/08
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A speakerphone which employs non-linear amplifiers to compress transmit and receive signals, and level detectors to determine levels of the compressed transmit and receive signals. Compressed transmit and receive signal levels are compared against one another by a comparator with hysteresis, to enable one of two speakerphone modes of operation--either a transmit mode or a receive mode. Fixed attenuators are switched into either the receive signal path or into the transmit signal path, depending upon the current speakerphone mode. The speakerphone functions described herein are readily implemented using inexpensive control circuitry and a standard telephone line interface, which can be shared by a telephone handset and other components of an integrated telephone system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.