Communication system providing simultaneous two-way transmission
US4380062A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 22, 1981 |
| Grant date | Apr 12, 1983 |
| Priority date | — |
| Expiry date | Apr 22, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/56
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A two-wire, carrier-type communication system is provided which enables simultaneous two-way transmission over two-wire circuits in the same spectrum. Carrier signals in quadrature are used to allow separation of signals within the same frequency spectrum. The carrier recovered at each subscriber station is used to demodulate the received signal and, after being phase shifted 90.degree., is applied as carrier to the transmitter modulator. The transmitters at the subscriber stations are thus the same as that at the central office but are locked to the receiver and 90.degree. out of phase. A bidirectional control phase adjustment network at the central station adjusts the phase of the signal received thereby until the received carrier is 90.degree. out of phase with the transmit carrier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.