Speakerphone with dynamic level discriminator
US4147892A · kind A · utility
10Cited by
2References
3Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jan 30, 1978 |
| Grant date | Apr 3, 1979 |
| Priority date | — |
| Expiry date | Jan 30, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/10
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In this speakerphone the peak value of the microphone output must be above the (variable threshold) average value to cause switching to transmit mode, thus providing dynamic compensation for ambient noise. In addition, a feedback path rapidly reduces the average value threshold if ambient noise such as a fan suddenly stops to cause the average value to be momentarily larger than the peak.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.