Fiber Optical Monitoring System

Optical Fibre

The optical fibre is undoubtedly the only technology that meets the bit-rate requirements of most new services. Bit-rates in the range of up to 10 Gbits/s are now rather common and will be shortly overtaken by WDM (Wavelength Division Multiplexing) technologies that will support hundreds of Gbits/s and even more.

Quality of Service

In case of failure, the disaster is in proportion with the capacity of the broken link. Thousands of users are sometimes suddenly disconnected. The Quality of Service is clearly of paramount importance.

Pro-active maintenance is therefore essential. The optical fibres must be permanently monitored in order to detect the defects and anticipate the failures.

However failures sometimes occur. The maintenance team must then fix the link urgently. For that they need accurate and reliable data. A precise diagnosis and location of the defect saves precious time and much money.

Reflectometry

FiberCare is designed to monitor networks, made up of monomode optical fibres, working in point-to-point as well as point-to-multipoint (PON) architecture. The measurement technique is based on the most advanced reflectometry technologies.

Every FiberCare unit monitors from 1 to 10 fibres and permanently tests each fibre within a 3-minute period. Thanks to accurate signal processing, any defective section or cut-off is detected in a range from approx. 100 km. The uncertainty in the defect location is approx. 5 m.

FiberCare is primarily used for curative purpose, since the diagnosis and localisation greatly help the field team. However, the role of FiberCare in pro-active maintenance is at least as important. The detection of defective sections, that would cause failures (connector ageing, water penetration, cable curvature, etc.) is the basis for QoS.

The optical fibres are statically connected to FiberCare. No optical switch is needed. On the one hand, this ensures higher reliability and, on the other, quickens the process since all the fibres are simultaneously tested. In addition, its great modularity (optical board for 2 fibres) allows flexible configurations and progressive investments.

A FiberCare system includes a number of Optical Test and Diagnostic Units (OTDU) and an Optical Main Control Unit (OMCU).

Optical Test and diagnostic unit

This device performs the measurement, and sets the diagnostic accordingly. Fibres are permanently connected to Optical Measurement Boards (up to 5 OMB's per OTDU), each monitoring 1 or 2 fibres at the same time.

The OTDU's are controlled :

• either locally by means of a PC (possibly a portable computer),
• or remotely from the Optical Main Control Unit, through PSTN or PSDN (X.25 or TCP/IP).

Optical main control unit

This device is in charge of controlling the OTDU's remotely. The OMCU is a PC running under WINDOWS, that permanently displays the status of the network and alerts in case of disruption. Working as a server, the OMCU can also provide several client terminals with the same information.

Measurement modes

The OTDU works either on spare fibres ("non active fibres") or on active fibres. Even if testing non active fibres is still popular, one should recognise that in this case only fibres which incur no risk are monitored! Working on active fibres is clearly much more efficient.

In order to test active fibres, optical components, including a coupling device and optical filters, are inserted into the network. The OTDU works in a waveband different from the operating one, in order not to interfere.

Thanks to this new approach the optical fibres that ensure your business are protected!