同步数字

• Transmission and multiplexing . optical interfaces for equipment and systems relating to the synchronous digital hierarchy uit - t recommandation g . 957 modified
  传输和多路通信.同步数字体系设备和系统用光学接口
• The main transmission media of sonet / sdh is fiber . sdh is developed with optical networks and has become the main hierarchy of today ’ s transmission network
  光同步数字传送网( sonet / sdh )主要以光纤为传输媒质,它随着光网络的发展不断壮大,成为现代传输网络的主要传送体制。
• Abstract : the special feature of sdh and its dominant position in long distance communication of factories and mines were described , and an engineering design was llustrated
  文摘:论述了sdh同步数字传输系统的特点及在厂矿企业远距离通信中的优势，并结合实例介绍了其工程设计方式。
• Finally , it should be noted that our polling cycles for ce donald tsang , secretaries of departments and directors of bureaux are all different , so comparisons should best be made using synchronized figures
  须要注意，是次发放所涉及有关特首、司长和局长的民望数字，由于调查周期不同，同步变化比较应以同步数字为基础。
• Sdh ( synchronous digital hierarchy ) has some primary advantages such as synchronous multiplexing , standard optical interface and strong network management compared with pdh ( plesiochronous digital hierarchy )
  同步数字体制( sdh )与传统的伪同步数字体制( pdh )相比,有三大核心优势,即同步复用、标准光接口和强大的网管能力。
• Sdh possesses the unified network node interface ( nni ) and standardized information class structure in the world . sdh can be compatible with pdh . it makes all the transmission network systems can communicate with each other on the level of stm - n
  Sdh具有全球统一的网络节点接口,标准化的信息等级结构,能够兼容pdh准同步数字系列,使得全世界传输系统能够在stm - n级别上实现互联互通。
• Optical relay network technoiogy is to buiidup various teiephone networks by the flexible sdh transmission equipment working with stored program control switches . at present , it has been adopted by most of telecom operators in iocal networks of pstn and becomes an eff6ctive solution to imp the operation cost , improve the qos , as well as faciiitat6 the oam
  光中继组网就是利用同步数字体系( sdh )传输设备本身组网的灵活性来配合程控交换机组成各种电话网络，在目前的公共电话交换网络( pstn )中的本地网络中，较多地被电信运营商所采用。
• Fully considering the system ' s reliabilty , being real - time , speed and extensibility , it finally chooses the sdh as the system network of cors through deep compration and alalysis of four special data lines supplied by china telecom , so that an effective interconnection among the stations and the workstations in the control - center comes true
  摘要充分考虑系统可靠性、实时性、通信速率、可扩充性等因素，通过对中国电信提供的4种数据专线服务的综合分析比较，选择了同步数字体系作为系统通信网络，实现了控制中心各工作站和各基准站之间的高速互联。