| 摘要 |
A data transmission system is used for the transmission of a large number of telephone channels between nodes in a transmission network built as a Synchronous Digital Hierarchy (SDH), where a pulse frame (e.g. STM-1) contains a large number of bytes, each of which can be used for the transmission of a telephone channel or of overhead signals for the administration of the system, and where signals from a Plesiochronous Digital Hierarchy (PDH) are introduced into the pulse frame of the Synchronous Digital Hierarchy, so that the signals from the Plesiochronous Digital Hierarchy when introduced do not occupy all the bytes in said pulse frame. At least some of the bytes of the pulse frame which are not occupied by introduction, are used for the transmission of user-specified data signals. |
