Installation guide

Appendix: Handling fiber
110 FTTH Application Guide
• Store unused dust caps in re-sealable containers to prevent them from
becoming contaminated with dust or other particulates which could then
contaminate the ferrule.
Installation testing
When installing fiber, especially GPON installations, you should have a link
loss budget map, then as you install components, test the attenuation before
and after each component. This testing should include testing before and after
long leads. Matching the actual results with the theoretical link budget loss
figures should help identify problems with the installation.
Testing equipment
There are a number of tools which can be used for testing optical lines.
• PON optical power meter
Tests the strength of the optical signal, use for testing transmit and receive
power levels
• Optical Time Domain Reflectometer (OTDR)
OTDRs help identify breaks and stresses in spans and splices. OTDRs
also help identify losses from splitters.
The OTDR creates a trace of signal power received against the time a
pulse is launched into the fiber. The OTDR analyzes the signals that are
returned by reflections caused by connectors, splices, bends or other
issues (such as errors in the fiber that cause reflections). These reflections
from the fiber are seen as events along the time axis
• Light source
Provides a signal for testing.
• Fiber probe
The fiber probe is basically a handheld microscope which has a viewing
screen to inspect connectors and cable ends which are being prepared for
splicing.
Physical layer issues
Bend radius
Optical cables may not be bent smaller than a certain radius. The signal will
refract rather than bend along with the cable. You may actually be able to see
light through the insulation which means the light is not being efficiently
transmitted down the cable. The tighter the bend radius, the greater the signal
reduction.