MODERN METHODS OF TESTING "DARK" FIBERS

At the stage of commissioning a fiber-optic communication line, it is mandatory to perform a set of measurements of its parameters according to the approved program in order to verify that the characteristics of all components comply with the manufacturers' specifications, as well as to analyze the quality of the work performed (channel integrity, absence of damage, attenuation rates, etc.)

In this article, we want to share our knowledge and experience in this area. Despite the existence of a unified ITU recommendation on certification of fiber-optic communication lines (ITU-T G.650.3 "Testing methods for laid single-mode fiber-optic cables "), each test can be performed in several ways using different instruments. ITU-T Recommendation G.650.3 prescribes the following measurements for all fibers:

Level 1 - General:

inspection of the end surface of the connector,
attenuation in the channel,
splice loss, location, fiber uniformity and lengths.

Level 2 - checking the quality of service or data rates:

spectral attenuation,
PMD,
HD.

In the following, we will look at the various aspects related to the types of measurements listed above (general concepts and best practices), and present a number of tools for their implementation, offered by EXFO Inc. (Canada).

Connector Inspection

Before starting testing, it is necessary to clean and record each detachable fiber connection in the executive documentation.

Detachable fiber splice graph

Long-term analysis shows that most of the faults occurring on FOCLs are related to the state of the connectors. Above are the data of the survey of the owners of communication networks and organizations involved in their construction, conducted by "NTT Advanced Technologies".

Inspection and cleaning of the connector end face is an important part of any test described in this article. Dirt, dust, microparticles, grease and other substances falling on the end of the ferula negatively affect the quality of the signal transmitted through the fiber - the stronger, the higher the transmission speed. Visual inspection of the ferrule remains the best solution, but it is highly dependent on the qualifications of the specialist, as a result of which defects can go unnoticed. Therefore, we recommend that you conduct a pass / fail inspection using software analysis to reduce human error.

Ideally, use the FIP-430B automatic video microscope with integrated ConnectorMax2 software that conforms to IEC and IPC standards. This device independently centers and focuses the image, turning a complex measurement process into a simple and quick one-step function that is accessible even to inexperienced personnel.

For more information about: Benefits of Dark Fiber