BRANCH-E&TC ENGINEERING

SEM – 4^th

SUBJECT-DATA COMMUNICATION AND COMPUTER NETWORK

CHAPTER-02- data transmission & media

TOPIC- data transmission media

Ay-2021-2022 ,summer-2022

FACULTY-ER V BEHERA.(LECTURER E & Tc engg dept)

Data Transmission Media

7.2

Figure 7.1 Transmission medium and physical layer

7.3

Figure 7.2 Classes of transmission media

7.4

7-1 GUIDED MEDIA

Guided media, which are those that provide a conduit from one device to another, include twisted-pair cable, coaxial cable, and fiber-optic cable.

Twisted-Pair Cable�Coaxial Cable�Fiber-Optic Cable

Topics discussed in this section:

7.5

Figure 7.3 Twisted-pair cable

7.6

Figure 7.4 UTP and STP cables

7.7

Figure 7.5 UTP connector

7.8

Figure 7.6 UTP performance

7.9

Figure 7.7 Coaxial cable

7.10

Table 7.2 Categories of coaxial cables

7.11

Figure 7.8 BNC connectors

7.12

Figure 7.9 Coaxial cable performance

7.13

Figure 7.10 Fiber optics: Bending of light ray

7.14

Figure 7.11 Optical fiber

7.15

Figure 7.12 Propagation modes

7.16

Figure 7.13 Modes

7.17

Table 7.3 Fiber types

7.18

Figure 7.14 Fiber construction

7.19

Figure 7.15 Fiber-optic cable connectors

7.20

Figure 7.16 Optical fiber performance

7.21

7-2 UNGUIDED MEDIA: WIRELESS

Unguided media transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication.

Radio Waves

Microwaves

Infrared

Topics discussed in this section:

7.22

Figure 7.17 Electromagnetic spectrum for wireless communication

7.23

Figure 7.18 Propagation methods

7.24

Table 7.4 Bands

7.25

Figure 7.19 Wireless transmission waves

7.26

Radio waves are used for multicast communications, such as radio and television, and paging systems. They can penetrate through walls.

Highly regulated. Use omni directional antennas

7.27

Figure 7.20 Omnidirectional antenna

7.28

Microwaves are used for unicast communication such as cellular telephones, satellite networks,�and wireless LANs.

Higher frequency ranges cannot penetrate walls.

Use directional antennas - point to point line of sight communications.

7.29

Figure 7.21 Unidirectional antennas

7.30

�Infrared signals can be used for short-range communication in a closed area using line-of-sight propagation.

Wireless Channels

• Are subject to a lot more errors than guided media channels.
• Interference is one cause for errors, can be circumvented with high SNR.
• The higher the SNR the less capacity is available for transmission due to the broadcast nature of the channel.
• Channel also subject to fading and no coverage holes.

7.31

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McGraw-Hill

• The McGraw-Hill Companies, Inc., 2000