光纤通信网的发展趋势迄今为止，我国光纤通信网全部是采用准同步数字体系（ＰＤＨ）。随着光通信网络的不断扩展，网点和设备的不断增多，继续采用ＰＤＨ传输系统已不利光纤通信的发展，今后我国光纤通信网改用同步数字体系（ＳＤＨ）已成必然趋势。采用ＳＤＨ数字体系优... The development trend of optical fiber communication network Until now, all optical communication networks in our country adopt the quasi-synchronous digital system (PDH). With the continuous expansion of optical communication networks, network points and equipment, the continuous use of PDH transmission systems has been detrimental to the development of optical communication. In the future, it has become an inevitable trend for China’s optical fiber communication networks to switch to synchronous digital hierarchy (SDH). Using SDH digital system excellent ...