20
Fault Locating: Full Auto
Set Mode to Full Auto
Clean and Connect launch cable
Select Test Port: MM or SM
Select Fiber Type
Measuring Loss on an OTDR Trace
Select Launch Cable: Noyes (150m), None, User
In General Tab Set Distance Units: m, ft, kft, km, mi
Press Test key
• Position the left cursor [A] at the start of the
event
• Position the right cursor [B] beyond the event
where the trace returns to a constant slope
• Read the insertion loss ( Loss: in dB )
measurement
An OTDR trace shows relative power vs. distance.
The insertion loss (IL) between any two points (A
to B) on the optical fiber link under test equals the
trace level at A minus the trace level at B.
To measure the end-to-end loss of a link, use a
launch and receive cable and put the [A] cursor
before the first event in the link and the [B] cursor
just after the tail of the last event.
A
B
IL
Launch Cable
Break
Trace displaying Fault
Expected trace
Two Point A/B Measurement
