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FIBRE-OPTIC NETWORKING
Mechanical Splicing
Mechanical splicing is the technology for joining
fibres that was introduced in the early eighties, yet it
has never really been successful and remained limited
to fast repair jobs. Over the years, this technology has
been enhanced from straight cleave installation to
angled cleave installation. The cleaving mechanism
and fibre installation system to create physical
contact is integrated in one tool. The cleaving blade
automatically progresses to a new position and has
an automatic end of life. This mechanism makes it
more compatible with the specific needs of the access
network.
A technician cannot simply mate and de-mate the
fibre ends the way connector technology would do.
The mechanical splice can be opened and the fibre
removed. The latter can be done separately for the
incoming or outgoing fibre, depending on the one
that needs to be replaced or requires access. The
fibres and the splice need to be taken out of the
organiser like for fusion splices. The process of fibre
organisation and fibre splicing requires specialists
with very specific skills, although for making the
splice, the special skills are limited to accurate coating
removal and adequate cleaning. The mechanical
splice is not sensitive to the fibre type and the
quality cleave is guaranteed by the tool features.
The installation time of mechanical splices is almost
the same as with fusion splices, but the set-up time
is about 30 per cent shorter, especially if there is
no cable preparation required. Even more time can
be saved in exceptional environmental conditions,
because the installation tool is insensitive to them.
Factory Pre-Termination
Factory pre-termination is when cables and fibres
are terminated to a connector in the factory. When
carefully planned, splicing jobs for specialised
technicians can be limited to the network
construction phase. With connectors, a de-mateable
product is available at the access points. Provisioning,
churn and network testing can be performed by
technicians without specific fibre skills, because
the organisers can be very simple. For some of the
applications, the pre-termination can be hardened
to eliminate the organiser. Connectors are accessible
on the outside of the network element, reducing the
need to access a product and the risk of disturbing
other lines.
The latest design version is particularly interesting
for the European market. It is more compact
and provides environmental sealing when the
mechanical connection is not adequately tightened.
Compatibility with the original hardened connector
can be guaranteed with a simple converter. With
pre-connectorised products, the connection time is
reduced from 20 to less than five minutes, including
the connector-cleaning step. When connecting
Plug-and-play solutions can result in higher cable inventory levels.
fibres with connector technology, there is no issue of
environmental sensitivity. Factory pre-termination
is also compatible with optical budget requirements
by selecting the appropriate grade as defined by
the international IEC standards. When properly
planned, pre-connectorised products do not add extra
connectivity points, thus eliminating extra optical loss
or reflections.
Conclusion
When comparing next generation access network
requirements with connectivity technology features,
the deployment of factory pre-terminated solutions
provides by far the best fit. The trend in Europe is to
go for a hybrid solution being pre-terminated at one
end and spliced at the other. Plug-and-play solutions
would be faster and would not require specialised
technicians, but they can result in unwanted burdens
such as higher cable inventory levels, more need
for over length storage, connectors that don’t pass
through ducts etc. The hybrid approach resolves these
issues: the least accessible or difficult end (wall or
pole mounted, in manholes etc.) is pre-terminated
and the other is spliced in the field.
Ultimately, coming from an all fusion spliced
situation in the external plant, today about one third
of homes are connected using factory
pre-termination and around one third use mechanical
splicing. There is no doubt that innovation will further
improve the solutions and each network will have
slightly different parameters, making a one size fits all
solution unlikely.
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