Full-duplex speakerphone circuit including a supplementary echo suppressor
US6282176A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 20, 1998 |
| Grant date | Aug 28, 2001 |
| Priority date | — |
| Expiry date | Mar 20, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/23
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A supplemental echo suppressor controls the attenuators in a transmit path and receive path to selectively set the attenuations based on the signal received from the far-end and the signal transmitted from the near-end. The attenuation levels are set to allow full-duplex communication. If both ends supply speech signals simultaneously, the attenuation is reduced, increasing the clarity of signals at both ends. Attenuation levels are also set when both ends are idle. If, however, the far-end user is talking and the near-end user is silent, and the echo at the near-end is low, then the attenuation is set high. Signal parameters are generated and monitored to control echo suppression. Suppression attenuation decisions are determined on the basis of normalized power estimates that are normalized to a background power estimate that is indicative of background noise. The power and noise parameters are used to determine engagement and disengagement of the suppressors. A slow noise signal is used as a control parameter for controlling suppression. The slow noise is a secondary, lower variance background power estimate that is derived from a background power estimate. The background power e…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.