Optical fiber provides many fundamental
advantages over alternative transmission technologies for
telecommunications applications. The comparatively limited
performance of copper conductor based systems forces the use of
expensive signal conditioning and regeneration equipment (e.g.,
amplifiers and repeaters) at much closer intervals than for fiber
optic systems.
A single line of a voice grade copper
system (i.e., 56 kbs) longer than a couple of kilometers requires the
use of in-line signal processing for satisfactory performance, and
even then is subject to the electromagnetic effects of interfering
radio frequency sources such as radio, television, cell phone, and
air traffic control broadcasts.
As information throughput requirements
increase with the demands of more data-intensive applications at the
end-user premises, the spacing between the copper-based repeater
points must decrease in order to maintain the same aggregate data
rate capability over a given length.
Contrast that to all-optical systems in
which it is not unusual to transmit 10 gigabits per second data rates
over hundreds of kilometers without the need for active signal
processing between the transmitter and receiver.
Additionally, as it becomes necessary
to increase the data transmission capacity or coverage area of a
telecomunications system, the diameter and weight of cables for
copper conductor systems increase much more rapidly than for optical
fiber systems, resulting in a proportionally higher increase in
materials, installation, and maintenance related costs.
The small size of optical cables,
coupled with readily available components that make efficient use of
the optical fiber’s transmission capabilities, enable them to be
manufactured and installed in much longer lengths than copper cables.
The virtually unlimited capacity of optical fiber also alleviates
fears of incurring significant long-term costs associated with
frequent system upgrades, extensions, or over builds.
The availability of long lengths of
individual lightweight fiber optic cables, up to 10 km or more, also
make the installation of fiber optic systems much safer, easier, and
less expensive, than comparable copper-based systems.
Because of their design, fiber optic
cables can generally be installed with the same equipment
historically used to install twisted pair and coaxial cables,
allowing some consideration for the smaller size and lower standard
tensile strength properties of fiber optic cable.
More importantly, fiber optic cable
design has progressed to the point where it serves as an enabling
technology for newer installation methods that are faster, less
expensive, and less intrusive to the environment than traditional
installation means. Optical cables can be installed in duct system
spans of 4000 meters (m) or more depending on the condition,
construction, and layout of the duct system, and the details of the
installation technique(s) used.
Even longer lengths of fiber optic
cable can be installed aerially, trenched, or buried in the ground
and ocean floor. These extra-long lengths of cable reduce the number
of splice points, thereby making the overall installation of optical
fiber based telecommunications systems more efficient. The small size
of fiber optic cable also saves on valuable conduit space in buried
duct applications.
This feature becomes even more
prevalent when considering some emerging cable types that are
specifically designed for use with air-blown or air-assist
installation techniques into miniature ducts that are only about one
centimeter in diameter.
Another advantage of optical fiber and
fiber optic cable is the inherent flexibility in design options,
allowing for the development of innovative products for specific
applications. Since optical fiber is a man-made composite glass
structure, it can be custom designed to meet optimal cost/performance
targets in any number of specific applications.
As it does not conduct electrical
current and is not affected by electromagnetic interference, fiber
optic cable can be made all dielectric, making it the ultimate in
electromagnetically compatible transmission media.
This eliminates such issues as
dangerous ground loops, the effects of voltage spikes from the
cycling of heavy electrical equipment, and requirements for separate
conduits for metallic conductors.
It also improves the security of
controlled transmission rooms as it is much more difficult to tap a
fiber optic line, and much easier to provide security for fiber optic
cable.
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