Issue link: https://www.e-digitaleditions.com/i/1081695
March/April 2019 I 55 perform the tests and provide a complete report with pass/fail verdict and a link view to the different network elements, their location and which are problematic. When troubleshooting a live network, use an OTDR equipped with a singlemode live port using an out-of- band 1625 nm wavelength. This allows networks with live traffic to be tested without interfering with other active users. With the multi-pulse OTDR technology, one can detect fault locations accurately. OTDRs are also helpful at finding macrobends, which are the second biggest cause of network problems. Macrobends can be caused by improper fiber handling. The light in the optical fiber "leaks out" of the fiber when it is bent. When there is a macrobend, it presents itself as a higher loss at the higher wavelength. By using an OTDR at two different wavelengths, the technician can validate whether the loss occurs at the higher wavelength. An iOLM will also pinpoint the location of a macrobend. SERVICE ACTIVATION To test service activation, use a PON power meter, which is a pass-through unit that checks the power both upstream and downstream. One end of the meter is connected to the OLT and the other end to an ONT. The pass-through connection allows the ONT and OLT to communicate with each other to confirm all signals are present. The unit is equipped with filter detectors for individual measurements of wavelengths. It supports GPON and next-generation PON and with special built-in PON awareness capability it adjusts itself automatically to the active wavelength to perform a power reading. REPORTING The last element for POL is reporting. The different tools discussed all provide PDF reports of the results. For example, iOLM provides a complete report with a view of all the different elements on the network. The technician sees a global pass/fail status as well as the individual status of every element identified. Furthermore, the technician would know the loss and reflectance for each of those events, so if there is a problem it is known right away where it is located. Tools, like OLTS, provide reports of the bidirectional testing with the loss and optical return loss and length link. When inspecting connectors with a fiber inspection probe, a complete report is generated with pictures of the connector end phase with overlay of the analysis that was performed on them, as well as global status and a table with events of the different zones that details the quantity and size of any defects. CONCLUSION For network managers and building owners who are installing a new network, either in a greenfield situation or a complete forklift upgrade, deploying POL technologies and singlemode optical fiber lays the foundation for a future-proofed network that will last for decades to come. Built on standardized, mature and mass-market PON technologies, an increase of LAN speeds can be achieved without any impact on the cabling infrastructure and with only minor updates of the end-point electronics. The evolution is not disruptive and can be incremental, as different PON technology generations can coexist on the same network. AUTHOR BIOGRAPHIES: Guillaume Lavallee is the product line manager at EXFO, a company specializing in Telecom Test & Measurement and Service Assurance. He is responsible for the optical products in the installation and maintenance division. Email: guillaume.lavallee@exfo.com. Steven Van Den Bergh is responsible for business development for POL solutions in Western Europe for Nokia. Steven can be reached at steven.van_den_bergh@nokia.com. Cemil Canturk is the senior marketing manager, Optical LAN, for Nokia in Belgium. Previously, he worked in Fixed Network Presales and Business Development for Nokia's Europe, Middle East and Africa regions. Email: cemil.canturk@nokia.com. This article was written on behalf of the TIA's Fiber Optic Technology Consortium, which represents technology leaders committed to providing the most current, reliable and vendor neutral information about fiber optics and related technologies for advancing new and better communications solutions and the Association for Passive Optical LAN, a non-profit organization composed of manufacturers, distributors, integrators, and consulting companies who are actively involved supporting the growth and education of the Passive Optical LAN industry.