Appendices
MobileAccess™ 1000/1200
34
UM-1000, Revision 2.2
Answer.
We have found that only the APC polish can offer consistently low levels of back
reflection with a high level of reliability.
There are connectors on the market with UPC, SPC and PC polishes that specify low back
reflection. The problem with these various polishes is that they are very fragile. A small
particle or even environmental changes can cause dramatic changes in the optical
performance. As a result performance degrading back reflection may suddenly appear
some time after the initial installation.
The APC, however, is much more robust and resistant to back reflections due to the
superior method used to eliminate back reflections. APC connectors are trouble free and
maintenance free. Once installed, there is no physical or environmental mechanism by
which the back reflection performance can be significantly changed.
If non-APC connectors are installed by the customer and provided for use with the
MobileAccess System, future system performance may be impacted and issues resulting
from a degradation of the fiber backbone performance are not warranted by MobileAccess.
What skills and experience should I look for when choosing a fiber cable installer?
6.
Answer.
Choose an installer who has experience with fusion splicing and APC connectors.
Only factory polished APC pigtails should be used and they should be fusion spliced to the
backbone cable.
Many installers lack experience with low back reflection singlemode links. This is because
the lower optical performance LAN data links which are more commonly installed in the
premises environment do not have stringent back reflection requirements. Installers who
have worked with the Telephone carriers or CATV installations, on the other hand, are
much more aware of low back reflection requirements.
What test documentation should I require from my fiber cable installer? Should I
require OTDR traces?
7.
Answer.
When using APC connectors, documentation of the fiber loss measurements of
each end to end fiber link is sufficient. A 1310nm light source and optical power meter are
the only instrumentation required to perform this testing. Back reflection from APC
connectors and splices are so consistently low, that back reflection measurements are not
required.
If, however, a non-APC connector is used, the back reflection measurements of each link
should also be documented. An optical back reflection meter should be used for these
tests. Unfortunately, most installers are not equipped with a back reflection meter. This is
another reason that use of the non-APC connector is strongly discouraged.
An OTDR trace lacks the resolution required to evaluate the closely spaced splice
junctures and connection pairings that are typical of In-building installations. OTDR traces
are only useful on long fiber spans where the fiber events are spaced at long intervals from
one another.
What are the maximum acceptable optical loss limits that are recommended for the
connectors, splices and optical fiber?
8.
Mated connector pair: <0.5 dB
Fusion splice:
<0.04 dB
Optical fiber cable:
<0.4 dB/Km
Total end to end link:
<1.5 dB
9.
I have a non-APC Singlemode fiber infrastructure already installed. Do I have to
install a totally new infrastructure for MobileAccess equipment?
Summary of Contents for 1000 System
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