Knowledge Base - Solution

40G Certifier Negative Loss of Fiber Testing

Tuesday, December 31, 2019
Submitted by ryan.grace on July 8, 2021 - 1:47pm
Problem: 
Testing with Viavi 40G Certifier fiber optic modules and the results are failing with negative loss readings.
Solution: 
Negative loss means the fiber under test is measuring less loss than what was recorded when the reference measurement was performed. This means there are poor reference conditions. Check the following things: 1. Make sure the proper reference type is selected (single jumper, dual jumper, etc..) 2. Make sure the fibers being used are reference quality. 3. After storing the reference preform an AUTOTEST on the reference fibers. It should have very minimal loss (<.03db when="" performing="" a="" two="" or="" three="" jumper="" reference="" disconnect="" and="" reconnect="" the="" fibers="" then="" run="" autotest="" again.="" do="" not="" remove="" tx="" connected="" to="" local="" remote.="" has="" been="" stored="" you="" may="" touch="" on="" unit="" if="" cannot="" get="" consistently="" good="" results="" jumpers="" disconnecting="" reconnecting="" are="" suspect="" should="" be="" replaced.="" bulkhead="" connectors="" replaced="" as="" well="" they="" can="" cause="" inconsistent="" results.="" once="" after="" breaking="" negative="" loss="" values="" no="" longer="" occur="" testing.="">

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