Data transmission system
US4799213A · kind A · utility
84Cited by
13References
3Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Sep 7, 1984 |
| Grant date | Jan 17, 1989 |
| Priority date | — |
| Expiry date | Sep 7, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/062
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Voice and data signals can be transmitted simultaneously yet independently over a subscriber telephone line. The speech and data use the same cable pair as far as the local exchange but thereafter they may be routed to the same destination or to different destinations, as desired. Each terminal unit (A or B) has a low pass filter (2) to isolate the voice and data. A data switch (5) switches an oscillator (6) by FSK. Switch (7) locks onto the Data Ready Interface (8). Bandpass filter (9) feeds the signal to the telephone line. A loop back switch LBS provides for testing from the exchange.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.