SDH Multiplexers: description, purpose

Digital multiplexers are logical combined devices that are designed for the controlled transfer of information from several data sources to a single output channel. In fact, such a device is a number of digital position switches. Accordingly, it can be concluded that the digital multiplexer is a switch of input signals to one output line. In this article we will consider a separate type of devices - optical multiplexers SDH.

Such devices are designed to work with data streams with the help of light beams, which differ in amplitude or phase grating, as well as in wavelength. The SDH multiplexers transmit information over E1 channels and Ethernet lines in transport fiber-optic networks. They work on one or two optical fibers (single-mode or multimode) at a speed of 155, 520 Mbit / s at a wavelength of 1550/1310 nm. Multiplexers SDH allow to realize up to 126 points of communication.

The advantages of such devices include resistance to external influences, technical security, protection against hacking of transmitted information.

SDH-multiplexers are easily scalable by including in the main module up to three additional modules for the transmission of Ethernet channels, E1 streams, service link, and the PM channel.

These devices are characterized by high "survivability" of the network. Implementation of E1 streams has a low jitter value, due to this, the norms for E1 are observed during the drift of synchronization, and also when the synchronization of the STM-1 system fails. Interface parameters allow you to track an error in the communication channel and switch to a spare channel. Optical path and power supply are reserved according to the scheme 1 + 1. That is, when working on one fiber optic channel, in case of cable damage , communication between subscribers is preserved.

Multiplexers SDH easily combined with other equipment such as SDH. They can work in both synchronous and asynchronous modes, it is allowed to use multimode and single-mode fiber. The SDH multiplexer supports the remote configuration and control over TCP / IP protocol, 10/100 BaseT.

Such switching devices are usually divided into two types: terminal and input / output. The difference between these types is not in the composition of the ports, but in the placement of the device in the SDH network. The terminal multiplexer completes the aggregate channels, switching among them a large number of output and input channels. The second type of devices transits the aggregate lines in transit, occupying an intermediate position on the highway. In this case, the information of the tributary channels is derived from the aggregate flow or introduced into it.

Most manufacturers produce universal multiplexers such as SDH, which are used as input / output, terminal, and cross-connectors - depending on the modules installed in them with tributary and aggregate ports.

In conclusion, we add that fiber-optic multiplexers are gaining increasing popularity due to the intensive development of this type of communication. The future is for fiber-optic technology.