1 Below are the advantages of optical fibers. Match them with an appropriate explanation:
Advantages:
1 Potentially low material cost. 2 High immunity to interference and crosstalk. 3 Very large information bandwidth. 4 Small and light cable. 5 Complete electrical isolation.
Explanations:
a) This means that they are suitable for crossing places which contain lots of electrical apparatus that give off stray signals. A fiber-optic link is also difficult to 'tap'.
b) This means that the signal fades less so that repeaters can be more widely spaced,
с) This means that fibers can carry a lot of information, 8,000 or more telephone conversations,
d) This means that when manufacturers start to produce fiber in large quantities, the price will be relatively low.
e) This means that the cables can easily be laid and that they will not occupy much duct space.
2 Discuss the importance of the above advantages in using optical fiber in public telephone networks. Try to rank the above advantages in order of importance.
3 Complete the following tables:
|
|
Composition |
Types |
Main features |
Quality |
|
Glass fiber |
a…. |
stepped-index multimode |
overlapping |
|
|
b…. |
c…. |
d…. |
e…. | |
|
|
f…. |
g…. |
h…. |
|
|
Types |
Features |
Applications |
|
Light sources |
a…. |
b…. |
Multimode and monomode |
|
c…. |
d…. |
e…. |
|
|
Types |
Features |
|
Photo detectors |
a…. |
b…. |
|
|
c…. |
d…. |
4 Read the following paragraph. Fill in each blank with a suitable word given below.
Technologies, images, improved, digital, transmit, integrated, information, network, wires, progress, developments, increase, speed, reliability.
One of the most interesting ____ in telecommunication is the rapid ____ of optical communication where optical fibers are ____ conventional telephone ____ and cables. Just as digital technologies greatly ____ the telephone system, optical communication promises a considerable ___ in capacity, quality, performance and ____ of the global telecommunication ____. New ____ such as optical fibers will increase the ____ of telecommunication and provide new, specialized ____ service. Voice, computer data, even video ____, will be increasingly ____ into a single ____ communication network capable to process and ____ virtually any kind of information.
5 Reply to the following sentences with a suitable question:
1 Optical technology is a result of combining the laser and ultra-thin silicon fibers.
2 Optical systems can transmit pulses of light as far as 135 kilometers without the need for amplification or regeneration.
3 Optical technology is cost-effective and versatile.
4 Optical fiber provides cheaper bandwidth for long distance communication.
5 An optical equivalent of a transistor has been produced and intensive research on optical electronic computers is underway in many countries around the world.