Preparing Your OTDR for a Test
32
FTB-7000 Series
Launch Conditions for Multimode Measurements
The table below gives information about tests with the 50
μ
m and 62.5
μ
m
fibers.
Fiber type
Recommended mode filter
Remarks
50
μ
m
Perform a five-turn
mandrel-wrap (wrapping the
patchcord a minimum of five
turns around the mandrel tool)
on the patchcord connecting
the OTDR to the fiber under
test.
As per FOTP-34:
³
For fibers with 3 mm
jacket: use a mandrel tool
with a diameter of 25 mm.
³
For fibers without jacket:
use a mandrel tool with a
diameter of 22 mm.
Nominal launch conditions are
overfilled.
Loss measurements can be
slightly pessimistic (higher loss)
when compared to loss
measurements done with a
50 MMF source compliant to
FOTP34, Method A2.
62.5
μ
m
No mode filter required.
Loss measurements similar to
those obtained with a power
meter and a source that is
conditioned according to
FOTP34, Method A2.
I
MPORTANT
If you test with 50
μ
m fibers, EXFO recommends that you use a
mode filter (mandrel-wrap). Otherwise, you may obtain results with
a 0.1 to 0.3 dB excess loss.
