Add-Drop-Multiplexer

An add- drop multiplexer is a device of the multiplex technology, which both add one or more sub-signals (add) and also from the multiplexed signal component signals found in a multiplexing signal (drop) can. The received multiplexed signal is forwarded unchanged to this add / drop changes.

The add-drop multiplexer thus considered as an extension of the conventional multiplexer, which is, at the end of transmission lines, used only as a terminal multiplexer.

Use

The add-drop multiplexer is used as a network element in the course of linear transmission lines, or the ring network configurations.

There he coupled out of the aggregate side signals (STM-1, STM- 4, ...) from one or more of the partial signals contained therein and provides them to its local loop available. From there, they will be redirected to subordinate network elements in the network hierarchy.

In the reverse direction, he adds tributary ( engl. adj. = Tributary on forward ) signal originating from the secondary network elements, as part signals in the aggregate- side signals and ensures that they are forwarded through the aggregate- side interfaces on the network.

Terminal Multiplexer

Is a device of the SDH technology capable of completely dissolving a multiplexed signal into its constituent component signals respectively to form from such a multiplex signal, it is called terminal multiplexer. The terminal multiplexer is required in the SDH network at the end of linear lines. These must include inflowing signals ( tributary signal ) derived from its sub- network elements together into an aggregate signal, which it forwards to the network.

The add-drop multiplexer is an extension of the terminal multiplexer. While this has only one -side interface units, the add-drop multiplexer has two STM interfaces with the same level of hierarchy.

Technology

Add- drop multiplexers have become possible for the first time to the SDH technique. In the PDH technique, it was still necessary for synchronization reasons, first dissolve the entire received multiplexed signal in all its individual component signals, and then add another part to signal after a resynchronization.

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