Audio and full duplex digital data carrier system
US4330687A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 1979 |
| Grant date | May 18, 1982 |
| Priority date | — |
| Expiry date | Mar 14, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/12
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A subscriber data carrier system for simultaneously carrying both base band telephone signals and full duplex digital data transmissions on a single pair of nonloaded telephone wires is disclosed. That is, the system provides for simultaneous conventional telephone signaling and audio communication and full duplex digital data communication between a pair of subscribers, each connected to the same main distribution frame of a central office by a single pair of nonloaded telephone wires. The system includes a modem (21) located at each subscriber's premises. The modems are connected to the subscriber's telephone (23) and digital data terminal (25). The modems include data transmitters (47) and receivers (49) that convert digital data from binary form into FSK form for transmission and from FSK form into binary form upon reception. More specifically, the transmitters include a frequency synthesizer (59) that produces one or the other of two FSK signals (F1 or F2) depending upon the binary nature (0 or 1) of a particular data bit to be transmitted; and, the receivers include frequency detectors (67) that detect two other FSK signals (F3 and F4) and, depending upon the frequency of the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.