| 摘要 |
<p>PURPOSE:To prevent out-of-frame synchronization from occurring continuously and to shorten a time required for pull-in by always inserting the prescribed frame synchronizing pattern in a frame synchronizing bit in a loop at each communication node. CONSTITUTION:An exchange control circuit 13 at each node controls a switch 16 in the frame synchronizing bit position to insert the synchronizing pattern that a synchronizing pattern generator circuit 17 generates unconditionally. The circuit 17 generates the synchronizing pattern according to a frame phase at the node, and supplies it to the switch 16. Since the frame phase at the node is constant, the signal with the frame synchronizing bit in a fixed position without fail is transmitted regardless of the frame synchronization state in a frame synchronizing circuit 10, and out-of-frame synchronization never occurs unless otherwise the erroneous transmission happenes.</p> |
