The Research On Transmission Of Clock Signals In Digital Synchronization Network

The digital synchronization network, as one of the three telecommunication supporting network, provides high-quality clock signals for equipments which need synchronization and has huge effect in normal and stable running of telecommunication network. A digital synchronization network covering all the cities and towns in Henan province has been built up, with Zhengzhou, the long-distance service communication center, as its synchronization center. It lays foundation for the future developing of communication services. However, with the gradual expanding of network capacity and the complicating of network structure, how to transmit clock signals effectively and plan the synchronization network reasonably becomes more and more important for technicians.This paper discusses the basic knowledge of digital synchronization network, the BITS(Building Integrated Timing System) and the transmissions of clock signals in PDH system, SDH system and DWDM system. The author has taken part in the maintaining of digital synchronization network for years. Based on deep investigation, analysis and research of the clock signals transmitting in Henan province trunk telecommunication network, this paper achieves the following results:1.Bring forward the basic principles of choosing and configuring the input/output physical ports, SSM bytes and clock sources by comparing and analysing the clock performance of SDH equipments in the present network.2. After discussing the principle of Clock Protection Switching and planning using Notel equipments, provide a new design solution, which considers all the possible troubles, distributes clock sources reasonably and solves the two clock sources problems in present network.3. Analyse the common Clock Protection Switching troubles and suggest paying attention to the configuration of SSM bytes to make sure the whole network working at one clock source.4. Test and verify the clock transmission performance in different systems using the monitoring function of Network Management System and put forward the clock priority configuration. 5. Comparing the two methods of timing signals transmission in DWDM system, advance the method of transmitting clock signals using optical free monitoring channels so as to improve the safety of the network.The research on clock signals transmission will contribute to the future planning and design of digital synchronization network. The complete synchronization of the whole network equipments will conduce to a more stable and reliable running of service network.