知识与财富的链接
从同步数字系列（SDH）的产生背景、工作原理出发,介绍了SDH的主要设备、网络结构和自愈环;从传送网的分层结构分析了SDH和ATM的关系,从而对电力通信网是否采用SDH提出了几点建议;最后介绍了SDH的发展方向。
Based on the background and principle of synchronous digital hierarchy SDH ,the network architecture and self- healing rings of SDH are introduced.Application of SDH in transm ission network,its relations with ATM and suggestions on whether SDH should be adopted in power comm unication network are presented.L astly,the prospect and developm ent of SDH are discussed.
