Method and device for frequency translation
US4375691A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 26, 1980 |
| Grant date | Mar 1, 1983 |
| Priority date | — |
| Expiry date | Sep 26, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/2801
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A digital communications system includes a plurality of master stations communicating with a plurality of terminals over a single communication line which carries a plurality of duplex communication channels, each corresponding to a particular master station. A frequency translator coupling each terminal with the communication line permits the remote station to selectively communicate over any of the channels by translating the frequency of a selected channel to that of the terminal's receiver and by translating the frequency of the terminal's transmitter to that of the selected channel. Upon selection of a particular channel, the terminal's transmitter is disabled for a duration sufficient to allow its receiver to pick up a resynchronization signal periodically sent out by the master station whose channel has been selected. The receiver then enables the transmitter in synchronism with any other terminals using the same channel. The translator employs a pair of multiple frequency oscillators controlled by a counter whose output corresponds to a selected channel. The counter is advanced by a manually operable switch, or alternatively, by a remotely generated digital word.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.