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| Number | Title | Issue Date |
| 4434324 | Reversal of connections of telegraphic line wires upon detection of unwanted polarity of the loop current 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 o... | 02/28/1984 |
