Since its
first proposal in 1966 the economics behind optical fiber technology have
changed radically. The major components within the communications system
comprise the fiber (and the resulting cable), the connections and the
opto-electronic conversion equipment necessary to convert the electrical signal
to light and vice versa.
In
telecommunications, optical fiber carries information not only in the trunk
network but also to the local exchanges. For motorway surveillance the use of
optical fiber is mandatory in many areas. At the data communications level all
the major computer suppliers have some fiber optic product offering within
their cabling systems. Increasingly process control systems suppliers are able
to offer optical solutions within large projects.
The
remainder of this book deals with these topics individually whilst building in
a modular fashion to ensure that fiber optic cabling networks most fully meet
their potential as operating systems.
In the early
years of optical transmission the relatively high cost of the above items had
to be balanced by the savings achieved within the remainder of the system. In
the case of telecommunications these othervsavings were generated by the
removal of repeater/regenerator stations.
Thus the
concept of ‘break-even’ distance grew rapidly and was broadly defined as the
distance at which the total cost of a copper system would be equivalent to that
of the optical fiber alternative. For systems in excess of that length the
optical option would offer overall cost savings whereas shorter-haul systems
would favour copper – unless other technical factors overrode that choice.
It is not
surprising therefore that long-range telecommunications was the first user
group to seriously consider the optical medium. Similarly the technology was an
obvious candidate in the area of long-range video transmission (motorway
surveillance, cable and satellite TV distribution). The cost advantages were
immediately apparent and practical applications were soon forthcoming.
Based upon
the volume production of cable and connectors for the telecommunications market
the inevitable cost reductions tended to reduce the ‘break-even’ distance. When
the argument is purely on cost grounds it is a relatively straightforward decision.
Unfortunately
even when the cost of cabling is fairly matched between copper and fiber optics
the additional cost of optoelectronic converters cannot be ignored. Until
certain key criteria are met the complete domination of data communications by
optical fiber cannot be achieved or even expected.
These
criteria are as follows:
•
standardization of fiber type such that telecommunications product can be used
in all application areas;
• reductions
in the cost of opto-electronic converters based upon large volume usage;
• a
widespread requirement for the data transmission at speeds which increase the
cost of the copper medium or, in the extreme, preclude the use of copper
totally.
These three
milestones are rapidly being approached; the first two by the application of
fiber to the telecommunications subscriber loop (to the home) whilst the third
is more frequently encountered due to vastly increased needs for services.
Meanwhile
the economics of fiber optic cabling dictate that while ‘break-even’ distances
have decreased the widespread use of ‘fiber-to-thedesk’ is still some time away.
There is a popular misconception in the press that the ‘fiber optic revolution’
has not yet occurred. It is evidently assumed that the revolution is an
overnight occurrence that miraculously converts every copper cabling installation
to optical fiber. This is rather unfortunate propaganda and, to a great extent,
both untrue and unrealistic.
But in most,
if not all, cases the fiber optic medium is not a total solution but rather a
partial, more targeted, solution within an overall cabling philosophy. There is
no ‘fiber optic revolution’ as such. There is instead a carefully assessed
strategy offering the user the services required over the media best suited to
the environment.
What cannot
be ignored is the fact that fiber optic cabling is specifically viewed as a
future-proofed element in the larger cabling market and as such operates more
readily as an operating system deserving deep consideration at the design,
installation, documentation and post installation stages.
As has been
seen, the immediate cost benefits of adopting a total fiber optic cabling strategy
are dependent upon the transmission distance. With the exception of
telecommunications and long-haul surveillance systems the typical dimensions of
communications networks are quite limited.
The local
area network is frequently defined as having a 2 kilometre span. The vast
majority of fiber optic cabling within the data communications market will have
links that do not exceed 500 metres. Such networks, when installed using
professional grades of optical fiber, offer enormous potential for upgrades in transmission
equipment and services.
The choice
of components, network topologies, cabling design, installation techniques and documentation
are all critical to the establishment of a cabling network which maximizes the
operational return on investment.
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