Page 80 - DLIS408_INFORMATION_TECHNOLOGY-APPLICATIONSL SCIENCES

Unit 6: Information and Communications Technology

Figure 6.5: A coaxial cable Notes

Core Insulator Conductor Protective Sheath

There are two types of coaxial cables—Baseband and Broadband. The differences between these
cables are described in table 6.2.
Table 6.2 Differences between baseband and broadband cables
Table 6.2: Differences between baseband and broadband cables
Baseband Coaxial Cable Broadband Coaxial Cable
1. Baseband coaxial cable is a 50-ohm 1. Broadband coaxial cable is a 75-ohm
cable. cable.
2. It carries only digital signals. 2. It carries only analog signals.
3. It transmits a singles stream of 3. It can transmit many signals
digital data at a time with a very simul-taneously using different
high speed. frequencies.
4. It transmits digital signals at 10 to 80 4. It covers a large area and needs
Mbps depending upon the cable analogamplifiers to straighten the
length. For longer distances, signals signals perio-dically.
need to be amplified periodically.
5. Baseband coaxial cables are often 5. Broadband coaxial cables are tipically
used in local area networks. used for cable television transmissions.

6.5.4 Fiber Optic Cable

Fiber optic cable is a glass fiber, which transmits information in the form of fluctuating light (i.e.,
photons-beams of light). It is similar to coaxial cable in structure as shown in Figure 6.6 having the
following three parts:
(i) Core. The innermost part of a glass fiber is the core made up of glass having diameter upto
50 microns. The core is 8-10 microns in single-mode while 50 microns in multimedia fibers.
The data in the form of light is propagated through the core.
(ii) Glass Cladding. The core is surrounded by a glass having lower refractive index known as
cladding. The cladding works like a mirror and keep light into the core by a process called
internal reflection. Thus, cladding minimises the amount of light leaking from the fibers.
(iii) Jacket. The glass cladding is protected by a thin plastic jacket. A single glass is thinner than
the size of a human hair. Thousands of these fibers are typically grouped together in
bundles, protected by an outer sheath as shown in Figure 6.7.

Figure 6.6: Fiber optic cable

Core Cladding Jacket

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