Patent ID: 6222892
Filing Date: 2001-04-24
Classification: H04J

Abstract:
An apparatus, disposed in a transmission unit that composes a network, for selecting one of a plurality of clock references received by the transmission unit as an active reference for controlling the transmission unit or as an active reference for supplying a timing to an external unit connected to the transmission unit corresponding to a quality level of each of the clock references sent with a corresponding synchronization message, comprising:synchronization message detecting means for detecting the synchronization message from a received signal;synchronization message processing means for controlling whether or not to select a clock reference received corresponding to the quality level of the clock reference sent with the synchronization message as the active reference; andstate detecting means for detecting the state of said synchronization message detecting means,wherein said synchronization message processing means does not select the clock reference corresponding to the synchronization message detected by said synchronization message detecting means as the active reference when said state detecting means has determined that said synchronization message detecting means is not in a normal state.