An OTDR trace shows an event at 4km that appears to be a "gainer" (the trace goes up, showing negative loss). What is the actual physical cause of a gainer in an OTDR trace?
Answers
ASplicing two fibers with different backscatter coefficients (e.g., mismatch in core sizes or MFD)
BThe splicing machine added power to the optical signal
CThe OTDR laser pulse is reflecting off a mirror-like finish
DThe fiber was repaired with an optical amplifier
Correct answer: A — Splicing two fibers with different backscatter coefficients (e.g., mismatch in core sizes or MFD)
A gainer is an optical illusion on an OTDR caused by splicing a fiber with a lower backscatter coefficient to one with a higher coefficient. More light scatters back, making it look like a gain in power.
MIFOTRA exam practicealigned to TIA-568.3-D / ITU-T G.652·4 marks·Hard