Overview

Obtaining connector-level insertion loss (IL) and return loss (RL) for hybrid cables is complicated by the different connector types on either end of the cable. Hybrid cables cannot simply be flipped to test the reverse direction when the reference and device under test (DUT) connectors are no longer compatible. A test setup comprised of the OP940 IL and RL Meter with two detectors, the OP725 Benchtop Optical Switch, and OPL-Max Application Software solves the compatibility issue and allows for hybrid cable testing with high speed, accuracy, and repeatability.

*Details on how to perform these measurements through the front panel of the OP940 can be found in Application Note AN-111 Measuring Insertion Loss and Return Loss on Hybrid Cables.

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AN-116 Performing Insertion Loss and Return Loss Measurements Using a Single-Channel OP940

Overview

OptoTest’s OP940 allows operators to test Insertion Loss and Return Loss of fiber optic cables accurately and efficiently. Once Insertion Loss and Return Loss references are completed, the unit will automatically update test results on the screen in real-time.

Performing a Reference Measurement

Return Loss Reference

The OP940 references Return Loss by searching for the first large reflection in the reference cable. After such a reflection is found, measurements begin at a distance from the front panel to the unmated end of the cable. It is recommended that an unmated PC connector be used for RL reference (for more information see our White Paper) and that the number of connections between the front panel and the reference connector be minimized to reduce loss and reflectors to the OP940 front panel. The open PC connector should yield approximately 14dB reflection.

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