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70 | BROADBAND COMMUNITIES | www.broadbandcommunities.com | MAY/JUNE 2014 FIBER TESTING testing only the distribution and drop fber is a good bet. 9 Review the 1625 nm trace and event table to determine if there is a break or any excess losses or refections in the distribution and drop fbers. If so, locate the problem, repair the fault and verify the fx by rescanning the fber using the same 1625 nm test. To precisely pinpoint macrobends or breaks within a splice enclosure or an access point, disconnect the OTDR and connect a visual fault locator (VFL, a visible red laser). Enable the VFL and look for the point where the fault causes red light to escape from the fber. 10 If no excess losses or refections were identifed in the OTDR trace, rescan the FTTx PON from the same location at 1625 nm using the "Test through Splitter" setup. Tis will provide a trace of the distribution and drop fbers with sufcient dynamic range to see through the splitter and measure the splitter loss. As other probable causes have been eliminated, likely problems are a break or macrobend at the splitter or a disconnection of the splitter from the distribution fber. Tese problems will manifest themselves either as excess loss at the splitter or as the fber end being detected at the splitter. Repair the fault and verify the fx by rescanning the fber using the same setup. 11 Once fber restoration is complete, verify that the proper downstream power levels are available at the end of the drop fber, clean and reconnect the drop fber to the ONT and verify that the ONT is synchronized to the upstream OLT. In summary, FTTx PONs present unique installation verifcation and maintenance troubleshooting challenges. Tese challenges are efectively overcome when technicians understand FTTx PON architecture and are equipped with tools designed to address the unique test requirements of FTTx PONs. v Michael Scholten is senior product marketing manager at AFL, one of the world's leading manufacturers of fber optic cable. Te company's product portfolio includes fber optic cable, transmission and substation accessories, outside-plant equipment, connectors, fusion splicers, test equipment and training. Its service portfolio includes market-leading positions with the foremost communications companies, supporting inside-plant, central ofce, EF&I;, outside-plant, enterprise and wireless areas. www.AFLglobal.com BBC_May14.indd 70 5/29/14 9:19 AM