COMMUNICATION SYSTEM TIME SYNCHRONIZATION METHOD, SLAVE STATION APPARATUS, MASTER STATION APPARATUS, CONTROL APPARATUS, AND PROGRAM

摘要

This invention is directed to suppression of time synchronization errors during channel switching. A time synchronization method is used in a communication system that performs protection switching and that comprises: a first network in which a master station (1) is connected to a slave station (10) via a plurality of physical channels including a currently used channel and a standby channel; and a second network that is connected to the slave station (10). The time synchronization method comprises a time synchronization step in which, if the slave station (10) does not detect any communication troubles of downstream signals transmitted by the master station (1), then a synchronization process is executed to synchronize, on the basis of the clock of the slave station (10) and timing information, the time information, which is to be transmitted to the second network, with the time information included in a time synchronization command and in which, if any communication troubles are detected or a switching notification is received from the master station apparatus (1), then the synchronization error caused by the difference between the clock of the slave station (10) and the timing information is suppressed.