OTDR recommended launch cable sizes
Knowledge Base - FAQ
What are the recommended length for launch cables for OTDR testing?
Desired length for a launch cable is based on the pulse width that is required for the test. The longer the pulse width then the longer your dead zones and you want your launch cable to clear the launch dead zone. Recommended lengths are:
10 to 20 meters for short pulse widths like 3ns/10ns/30ns
100-200 meters for medium pulse widths like 100ns/300ns
1-2 kilometers for long pulse widths like 3us/100us