Avitec AB FD-3100A ユーザーズマニュアル
2.2 Install Fiberoptic Cables
Once the location for each of the Remote Transceivers has been determined, the fiberoptic cable can be
installed between the Hub Shelf and these locations. The cable length can be up to 5 km.
You need to know the following:
Optical
installed between the Hub Shelf and these locations. The cable length can be up to 5 km.
You need to know the following:
Optical
Fiber
Singlemode,
1310nm
wavelength
Optical Loss
Good quality fiber should have an optical loss of
< 0.4 dB/km at 1310nm. There will be additional
optical loss due to connectors and splices but there
should be no more than about 0.5 dB loss through a
connector mating (optical connections are sexless)
and less through a splice.
< 0.4 dB/km at 1310nm. There will be additional
optical loss due to connectors and splices but there
should be no more than about 0.5 dB loss through a
connector mating (optical connections are sexless)
and less through a splice.
Optical Connectors
SC/UPC connectors. The “U” refers to “Ultra Polish”
which gives an optical return loss > 50 dB. One can
procure cable assemblies that are pre-terminated,
however the SC/UPC can be installed in the field
using the Seicor Unicam connector. The Hub Shelf
also uses SC/UPC connectors. IMPORTANT
NOTE: MAKE SURE TO USE AN SC/UPC
TERMINATION: THIS CONNECTOR IS AN
“ULTRA POLISHED” CONNECTOR WITH AN
OPTICAL RETURN LOSS > 50 dB. A
STANDARD SC/PC TERMINATION HAS A
HIGH RETURN LOSS AND WILL DEGRADE
LINK NOISE AND LINEARITY PERFORMANCE.
which gives an optical return loss > 50 dB. One can
procure cable assemblies that are pre-terminated,
however the SC/UPC can be installed in the field
using the Seicor Unicam connector. The Hub Shelf
also uses SC/UPC connectors. IMPORTANT
NOTE: MAKE SURE TO USE AN SC/UPC
TERMINATION: THIS CONNECTOR IS AN
“ULTRA POLISHED” CONNECTOR WITH AN
OPTICAL RETURN LOSS > 50 dB. A
STANDARD SC/PC TERMINATION HAS A
HIGH RETURN LOSS AND WILL DEGRADE
LINK NOISE AND LINEARITY PERFORMANCE.
Once the cable has been installed, the installer should check the quality of the optical path using an Optical
Time Domain Reflectometer (OTDR). This will check the optical path loss and the magnitude and location
of any reflections. The total return loss should be > 45 dB.
While checking the cables in this way, it is useful to label each cable near the connector as to which
Remote Transceiver it is for and whether it is for the transmit or receive path. Labelling the cable in this
way permits complete interconnection during installation with the system powered off. Otherwise, the
Remote Transceivers will have to be installed with the Hub Shelf power on with all fiberoptic cables
connected to it. This allows the installer to check which fiber is transmit by using an IR sensitive card (see
Recommended Tools).
2.2.1 Minimizing Optical Reflections
As discussed in the Functional Description, optical reflections can degrade the noise and linearity of a
fiberoptic link. In particular, reflections that reach the laser can be a problem. Keep all discrete reflections
to > 50 dB. The SC/UPC connectors are polished to a return loss >50 dB.
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