| 摘要 |
<p>In centrally controlled network changeover systems, the central stations are only informed about a reception of AIS signals or the finding of defects in the digital signal by digital cross-connect units but not by other link devices. Since the digital cross-connect units cannot recognise where an AIS signal has been fed in, identical messages may be supplied several times without indicating to the central station whether there is one or several fault points along the link. …<??>A modified AIS signal is introduced which consists of the familiar standardised AIS signal in the form of an all-ones signal and an identification. These are either equidistantly inserted single zeros with a frequency of less than 10<-3> or is an additional signal. When a digital cross-connect unit (8) receives a standardised AIS signal or recognises any other defect, it feeds a modified AIS signal into the outgoing link (15). Only the subsequent digital cross-connect units (9, 10, 11, 12) detect the modification and, in turn, feed in such a signal and dispense with a message to a regional centre (3, 4). The network management centre 1 switches a stand-by link (16) on the basis of the message of the digital cross-connect unit (8). …<??>The invention is used in centrally controlled network changeover systems. …<IMAGE>… </p> |
