ETSI ETS 300 166-1993 传输和复用(TM).基于准同步或同步数字体系的2,048 kbit/s设备的分层数字接口的物理和电气特性
Transmission and Multiplexing (TM) Physical and Electrical Characteristics of Hierarchical Digital Interfaces for Equipment Using the 2048 Kbit/s- Based Plesiochronous or Synchronous Digital Hierarchies