Interface circuitry for acoustic coupler compensation
US4288661A · kind A · utility
7Cited by
3References
7Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Feb 21, 1979 |
| Grant date | Sep 8, 1981 |
| Priority date | — |
| Expiry date | Feb 21, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/066
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
For the type of modem that transmits information by way of quadrature amplitude modulation (QAM) over a telephone line, an electronic circuit for compensating for amplitude distortion created by use of an acoustic coupler with an ordinary telephone handset. The circuit is positioned in the acoustic coupler between the modem and the coupler's microphone and receiver. This circuit compensates for amplitude distortion introduced by the acoustic coupling within the data transmission frequency bands of the modem.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.