CES测试中时钟恢复方式验证方法研究

摘要

The TDM service carried over packet network is commonly referred to CES service. The CES service requires the transparent transport of the service clock, which relates to the service clock recovery of the end mode in the network. The frequency of the customer TDM service must be accurately restored in the packet network exit. There are three methods for CES service clock recovery:system clock recovery, ACR and DCR. To verify the function of CES service clock recovery of tested packet transport equipment, it presents three verifying methods for service clock recovery, which are add-frequency-offset verifying method, out-of-synchronization verifying method and add-PDV verifying method. They are used to guarantee the preciseness and va-lidity of CES service clock recovery test.%分组网络上承载的TDM业务通常称之为CES。当分组网络承载CES的时候，需要保证业务时钟的透明传递，这就涉及到了网络上末端节点的业务时钟恢复问题。客户TDM业务的频率必须在分组网络的出口处精确地重新恢复。目前CES时钟恢复方式有系统时钟恢复、ACR和DCR 3种方式。为了更好地验证被测分组传送设备的CES时钟恢复功能，提出了加频偏验证法、去同步验证法、加PDV验证法3种CES时钟恢复方式的验证方法，确保CES时钟恢复功能测试的严谨性和正确性。