| 摘要 |
<p>PURPOSE:To effectively suppress deterioration in synchronization quality of a station installed in the vicinity of the end of the transmission network. CONSTITUTION:The SDH network provided with a host station and plural subordinate stations in which inter-station transmission is implemented by using a signal having a prescribed NNI frame structure is provided with a pointer extract section 11 extracting an AU pointer for a predetermined VC path among plural VC paths multiplexed in an STM frame used for the inter-station transmission, a counter 12 monitoring a pointer extracted by the pointer extract section 11 to count incidence number of times for positive stuff and negative stuff in a unit time of the VC path between the host station and its own station, a reference clock generating section 14 outputting a reference clock taking synchronization with respect to a frequency of the host station and a frequency synchronization control section 13 controlling increase/decrease in the frequency of the clock outputted from the reference clock generating section 14 based on the counter output.</p> |
