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Transmission Media

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Chapter 7 Transmission Media Figure 7.21 Unidirectional antennas Dish antennas Horn antenna Note the Cell antenna below the horns Cell Telephone antennas Infrared ... – PowerPoint PPT presentation

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Title: Transmission Media


1
Chapter 7
TransmissionMedia
2
Figure 7.1 Transmission medium and physical
layer
3
Figure 7.2 Classes of transmission media
4
7.1 Guided Media
Twisted-Pair Cable Coaxial Cable Fiber-Optic
Cable
5
Figure 7.3 Twisted-pair cable
6
Cable
Twisted Pair Cable
  • Twisted pair cable implies the use of balanced
    signaling
  • Twisted pair is used in telephony as well as
    local area networking
  • The shield can be wrapped around a single pair or
    over an entire group of pairs

7
Figure 7.4 UTP and STP
8
Table 7.1 Categories of unshielded twisted-pair
cables
Category Bandwidth Data Rate Digital/Analog Use
1 very low lt 100 kbps Analog Telephone
2 lt 2 MHz 2 Mbps Analog/digital T-1 lines
3 16 MHz 10 Mbps Digital LANs
4 20 MHz 20 Mbps Digital LANs
5 100 MHz 100 Mbps Digital LANs
6 (draft) 200 MHz 200 Mbps Digital LANs
7 (draft) 600 MHz 600 Mbps Digital LANs
9
Figure 7.5 UTP connector
10
UTP Cable and Connectors
PALO ALTO, Calif., and PISCATAWAY, NJ,- June 28,
1999 - Members of the IEEE and the Gigabit
Ethernet Alliance today announced that the final
milestone in the IEEE standards approval process
was reached last week when the 1000BASE-T
specification for Gigabit Ethernet over copper
(also known as IEEE Std 802.3ab) was unanimously
approved as an IEEE standard by the IEEE
Standards Association (IEEE-SA) Standards Board.
The standard defines Gigabit Ethernet operation
over distances of up to 100 meters using four
pairs of CAT-5 balanced copper cabling 1000BASE-
T is important for three reasons," commented
Colin Mick, technical editor of the IEEE 802.3ab
Task Force. "First, most of the cabling installed
inside buildings today is CAT-5 UTP, and
1000BASE-T will enable Gigabit Ethernet operation
over this installed base. Second, 1000BASE-T, on
a per-connection basis, is expected to be very
cost-effective which will stimulate market
demand. Finally, 1000BASE-T allows
auto-negotiation between 100 and 1000 Mb/s which
eases the migration path for customers."
11
Figure 7.6 UTP performance
12
Figure 7.7 Coaxial cable
13
Table 7.2 Categories of coaxial cables
Category Impedance Use
RG-59 75 W Cable TV
RG-58 50 W Thin Ethernet
RG-11 50 W Thick Ethernet
14
Figure 7.8 BNC connectors
15
Figure 7.9 Coaxial cable performance
16
Bending of light ray
Think of a mirage. You look along a road surface
on a hot day and see the reflected sky, looking
for all the world like a pool of water. Think
of window glass on the front of a
departmentstore. As you walk down the sidewalk
you cantsee whats inside. Once youre in
front of the window its easy to see
inside. These effects are related to the
Critical Angle
17
Figure 7.10 Bending of light ray
18
Figure 7.11 Optical fiber
19
Figure 7.12 Propagation modes
20
Figure 7.13 Modes
21
Table 7.3 Fiber types
Type Core Cladding Mode
50/125 50 125 Multimode, graded-index
62.5/125 62.5 125 Multimode, graded-index
100/125 100 125 Multimode, graded-index
7/125 7 125 Single-mode
22
Figure 7.14 Fiber construction
23
Figure 7.15 Fiber-optic cable connectors
24
Figure 7.16 Optical fiber performance
25
7.2 Unguided Media Wireless
Radio Waves Microwaves Infrared
26
Figure 7.17 Electromagnetic spectrum for
wireless communication
27
Figure 7.18 Propagation methods
28
Table 7.4 Bands
Band Range Propagation Application
VLF 330 KHz Ground Long-range radio navigation
LF 30300 KHz Ground Radio beacons andnavigational locators
MF 300 KHz3 MHz Sky AM radio
HF 330 MHz Sky Citizens band (CB),ship/aircraft communication
VHF 30300 MHz Sky andline-of-sight VHF TV, FM radio
UHF 300 MHz3 GHz Line-of-sight UHF TV, cellular phones, paging, satellite
SHF 330 GHz Line-of-sight Satellite communication
EHF 30300 GHz Line-of-sight Long-range radio navigation
29
Figure 7.19 Wireless transmission waves
30
  • Radio waves are used for multicast
    communications, such as radio and television, and
    paging systems.
  • They use a frequency spectrum from 3KHz to 300 MHz

31
Figure 7.20 Omnidirectional antennas
32
Omnidirectional antenna
33
  • Microwaves are used for unicast communication
    such as cellular telephones, satellite networks,
    and wireless LANs.
  • They use the frequency spectrum from 300 MHz to
    300 GHz

34
Figure 7.21 Unidirectional antennas
35
Dish antennas
36
Horn antenna Note the Cell antenna below the
horns
37
Cell Telephone antennas
38
Infrared
  • Infrared signals can be used for short-range
    communication in a closed area using
    line-of-sight propagation.
  • Not used commercially for LANs
  • Used commercially for short links
  • Infrared starts at 300 GHz
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