Hands-free telephone having a handset volume attenuator for controlling speaker volume in a hands-free adaptor
US5212722A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 29, 1992 |
| Grant date | May 18, 1993 |
| Priority date | — |
| Expiry date | Jun 29, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04W88/02
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A hands-free telephone for use on a vehicle includes a handset incorporating a radio section therein and a hands-free adapter incorporating a hands-free telephone unit therein. To prevent howling, the telephone includes two variable attenuators, or variolossers, each for changing the level of respective ones of a receive and a transmit signal to be applied to a speaker of the hands-free telephone unit and the radio section, respectively, so as to maintain the two levels in a predetermined relation. The telephone also includes in the radio section a variable resistor which may adjust the volume of voice signal to be delivered through an earpiece within the radio section which adjusts the volume of voice signal to be delivered through the speaker. The level-adjusted voice signal to be delivered through the speaker is controlled in level by a third variable attenuator simultaneously with the above-mentioned variable attenuators.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.