Reversal of connections of telegraphic line wires upon detection of unwanted polarity of the loop current
US4434324A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 27, 1982 |
| Grant date | Feb 28, 1984 |
| Priority date | — |
| Expiry date | Jan 27, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/027
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The system comprises at least one teleprinter station (1) connected to an exchange (3) by means of a transmission-reception line (2) and comprising a polarity detector (31) for the line circulating current, and a device (30) for reversing the connection of the line wires. If the wires erroneously become reversely connected following maintenance work on a line of single current type, then false call and conversation signals are generated which automatically trigger a checking operation in which the polarity detector is suitably examined under control of a ROM routine E controlling a CPU 84. If the current is found to be the reverse of the correct current, the reversing device is operated in order to reverse the polarity of the connection. In contrast, in the case of a double current line, the reversing device is operated when current is absent in the reception line, thus indicating an erroneous line connection. If the line current interruption is prolonged, a warning device (28) is activated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.