CELL SYNCHRONIZATION DEVICE, CELL SYNCHRONIZATION MONITOR DEVICE AND CELL RE-SYNCHRONIZATION DEVICE

摘要

PROBLEM TO BE SOLVED: To surely realize synchronization protection of a cell with respect to the synchronization system of a cell for an ATM exchange or the like. SOLUTION: A free-running frame generating circuit 101 generates a free- running frame. A phase adjustment circuit 102 adjusts a transfer timing of an input cell based on the free-running table. A thrice consecutive out of synchronism monitor section 103 detects out of synchronism of a cell frame by monitoring whether or not each pulse timing between the input cell frame and the free-running frame is not hit thrice consecutively. Then a thrice consecutive synchronization restoration monitor section 105 monitors whether or not each pulse timing between the input cell frame and an output of a counter 104 is matched with each other thrice consecutively to detect synchronization restoration of the cell frame. Then a re-synchronizing signal generating circuit 106 initializes the free-running frame generating circuit 101 by a pulse timing of the input cell frame to reset the thrice consecutive out of synchronism monitor section 103 to establish the re-synchronization between the input cell frame and the free-running frame.