| 摘要 |
In transmission links for digital signals, the location of a fault can be determined by closing a loop between two regenerative repeaters for two signal paths following a received loop closure command and transmitting via this loop test signals which are examined for errors at the receiving end by bit-by-bit comparison with the test signals sent out. The test signal used is normally a pseudo-random sequence which must not exceed a certain length in order to avoid synchronisation problems in the bit-by-bit comparison at the receiving end. It has been found that fault-locating is not possible in every case using this method. According to the invention, an additional pseudo-random sequence of comparatively very long periodicity is therefore additionally combined with the existing test signals, but at the receiving end, only an evaluation for code rule violations is carried out. This method is applied in particular in transmission links for digital signals with higher transmission rates. <IMAGE> |
