Use of Launch Cables
A launch cable consists of a spools of fibre with a specific distance, and should be connected between the OTDR and fibre link under test in order to qualify the front end connectors.
The length of the launch cable depends on the link being tested, but it’s generally between 150 m and 1000 m for single-mode and multimode testing.
The fibre length highly depends on the OTDR attenuation dead zone, which is function of the pulsewidth. The larger the pulsewidth, the longer the launch cable required.
PROACTIVE Connector Inspection
A single dirty fibre connection can affect overall signal performance. Proactively inspecting each fibre connection with a fibre microscope probe will significantly reduce network downtime and troubleshooting. Always follow this
simple "Inspect Before You Connect" process to ensure fibre end faces are clean prior to mating connectors.
A dirty OTDR port or a dirty launch/receive cable connector will impact the OTDR measurement. It needs to be inspected and cleaned before the launch cable is connected.