Method of transmitting sync clock and sync data between shelves of a

Abstract

A synchronization control method for a synchronous digital hierarchy system includes the steps of: at a first selecting unit, selecting a given number of timing sources, from among a plurality of first timing sources within a main shelf, in accordance with user setting data, and outputting the given number of the selected timing sources; at a first quality data generating unit, outputting quality data of one or more of the selected timing sources when the one or more of the selected timing sources have no quality data; at a second selecting unit, selecting one or more timing sources from among a plurality of second timing sources within a slave shelf when any timing sources set by the user setting data are included in the second timing sources within the slave shelf, and transmitting the selected one or more timing sources to the main shelf; at a second quality data generating unit, outputting the quality data of the one or more timing sources supplied from the second selecting unit, and transmitting the quality data to the main shelf; and at a first quality selecting unit, selecting a timing source having the highest quality value among the quality data from the first and second quality data generating units, from among the given number of the timing sources, and outputting the selected timing source to the main shelf as equipment clock, and transmitting the equipment clock to the slave shelf.