Method and apparatus for feedback suppression
US3944743A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 7, 1974 |
| Grant date | Mar 16, 1976 |
| Priority date | — |
| Expiry date | Jan 7, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/085
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A system for suppressing positive feedback in acoustical-electrical devices having acoustic or electric feedback paths or a combination of both. Electrical signals from a microphone are transmitted through a sampling switch to a signal storage device. The transfer rate and duration are controlled by a pulse generator driven by an oscillator to time domain process the signals. The discrete signals output from the signal storage device are smoothed by a low pass filter and used to drive follow on circuitry, e.g., a speaker. A plurality of switches, signal storage devices, oscillators and pulse generators can be arranged in serial or parallel to provide various processing combinations. Several embodiments of the system are employed in a bidirectional telephone unit having separate incoming and outgoing signal channels to enable full duplex mode operation. In one embodiment, the incoming signals only are time domain processed and used to generate signals for controlling a voltage control gain block in the outgoing channel. In another embodiment, both the incoming and outgoing signals are time domain processed. In another embodiment, both the incoming and outgoing signals are time domai…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.