Above is a single fibre strand
from a fibre optic cable. |
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Fibre
Optic cable works in a similar fashion to that of coaxial
cable. That is, a signal is bounced from the centre of the
cable, to the outside of the cable. The main difference however,
is that fibre optic cable uses glass as its signal conductor,
not copper wire as in coaxial cable. And, because it sends
light as signals, light devices are attached to the fibre,
rather than electrical radio frequency devices.
There are some great advantages to using
glass as a means of transmitting signals. Firstly, the cable
carries much more information, and secondly, because the signal
is travelling as a light frequency and not an electrical pulse,
it can travel MUCH more quickly, and much further. |
However, in order to gain the advantages
of speed and data quantity offered by fibre systems the system
must be installed properly. All splices must be done correctly,
and then each must be properly protected from water so that
water won't get onto the fibres and freeze, breaking the fibre.
Because splicing and fiber optic installation is very costly
to install and to fix, taking care during the initial installation
to make sure that it is done correctly will help to ensure
that the system lasts much longer.
Use of fibre optic technology in rural
and remote communities basically comes down to a few simple
issues:
- cost,
- whether the capabilities of the available
fibre optic cable types are suitable for the desired use
and terrain, and,
- whether skilled installers are available.
Fibre optic cable, if used, can be a very
flexible medium, from a way to extend an ethernet, to a way
to extend connectivity to the next remote village.
Fibre optic cable comes in both single-mode,
and multi-mode. For a rural or remote installation, single
mode is an appropriate choice as it is more forgiving for
these types of installations.
Both single and multi-mode cable also come
in many different varieties, as follows:
- ribbon cable:
is a flat cable, usually used indoors, which can be easily
routed under a carpet, to service users within an office.
- underwater cable:
not generally applicable to rural and remote users,
this cable is specifically made for underwater use, and
has specific enclosures for underwater splices.
- self-supporting
cable: is used in aerial installations, and generally
has either a steel or fibreglass strength member that supports
the cable, so that it is not necessary to string a supporting
messenger cable.
- burial cable:
is a strong armoured cable designed to be buried,
with or without conduit.
- dialectric cable:
this cable has no metal at all and is designed to be used
around power lines. This type of cable is extremely strong
and light, and can span incredible distances.
- supported cable:
this cable needs "messenger cable" to support
it, and needs to be lashed to the messenger cable.
- gel cables: these
waterproof cables are exterior only - they can't be used
indoors as they emit toxic chemicals during fire.
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TIP:
When putting up either self-supporting cable or messenger
supported cable, each puts different loads on power poles.
An engineer will need to check to make sure that any existing
poles can handle the load of the cable being installed.
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All of these cable types will need to be
connectorized or spliced in order to be hooked up to devices
to send data. Cable suppliers will be happy to help communities
with choosing both a cable type that is appropriate for their
needs, and with providing appropriate connectors if desired.
Additionally, Activity three of this module deals with preparing
fibre so that a community could save on fibre installation
costs by doing a portion of the work themselves, with the
option of hiring professionals to do either splicing or connectorization.
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