Selecting the correct Launch cable length

Applies to

OTDR and iOLM testing


What are the general guidelines for selecting the length of a launch and/or receive cable?


A simple general rule would be; A longer fiber under test requires a longer launch cable

The reasons are related to the desire to characterize the first and last connectors, as well as the longer pulse-width needed to fully characterize a longer fiber. 

The table below provides typical guidelines on the launch/receive cable lengths as well as pulse widths and acquisition times for different lengths of fiber.


  1. The above information shows typical values only and specific testing requirements may be different. You should always follow testing procedures provided by your own organization.
  2. The pulse-width and acquisition setting apply to OTDR only. For iOLM these parameters are managed by the iOLM acquisition algorithms. Nevertheless, the launch cable length guidelines do apply.
  3.  For more information, please consult the specification sheet.