A method of zeroing a light source and power meter by connecting them with only the launch jumper and recording that power as 0 dB. The receive jumper is then added and the link inserted, so the result includes the loss of both connectors at the link ends. Two-jumper and three-jumper reference methods exclude one or both end connectors and give lower numbers, so the method must be named on every report.
Reset to a one-jumper reference before the next panel, your numbers are lower than the fiber alone should lose and I don't trust them.
Never disconnect the launch jumper from the source after setting the reference, or the reference is gone and every reading after it is wrong.
Also heard as
- one-cord reference
- Method B
- single-jumper reference
Related terms
OLTS
Optical Loss Test Set: a light source and power meter used together to measure end-to-end link loss.
Insertion loss
The optical power lost when a component or a whole link is placed in the light path, measured in dB.
Launch cable
A long reference fiber placed between the OTDR and the cable under test so the first connector can be measured.
Loss budget
The calculated total loss a fiber link should have, built from fiber length, connectors and splices.