Transmission Media Surasak Sanguanpong nguan@ku.ac.th - - PDF document

▶
transmission media
SMART_READER_LITE
LIVE PREVIEW

Transmission Media Surasak Sanguanpong nguan@ku.ac.th - - PDF document

Oct 09, 2023 158 likes •276 views

1 / 17 Transmission Media Surasak Sanguanpong nguan@ku.ac.th http://www.cpe.ku.ac.th/~nguan Last updated: 25 November 2004 Applied Network Research Group Department of Computer Engineering, Kasetsart University 2 /

slide-1
SLIDE 1

1

Applied Network Research Group Department of Computer Engineering, Kasetsart University 1/17

Transmission Media

Surasak Sanguanpong nguan@ku.ac.th http://www.cpe.ku.ac.th/~nguan

Last updated: 25 November 2004

Applied Network Research Group Department of Computer Engineering, Kasetsart University 2/17

Type of Media

Twisted Pair Twisted Pair Wireless Wireless Wired Wired Coaxial Coaxial Fiber Optic Fiber Optic Microwave Microwave Satellite Satellite Medium Medium

slide-2
SLIDE 2

2

Applied Network Research Group Department of Computer Engineering, Kasetsart University 3/17

Electromagnetic Spectrum

Twisted pair Telephone service Coaxial cable AM radio FM radio and TV Optical fiber Satellite 102 103 104 105 106 107 108 109 1010 1011 1012 1013 1014 1015 1016

Radio Infrared Visible light Microwave

Hz microwave

Applied Network Research Group Department of Computer Engineering, Kasetsart University 4/17

Twisted Pair

  • Two varieties

unshielded shielded

  • uter insulator

copper conductors

slide-3
SLIDE 3

3

Applied Network Research Group Department of Computer Engineering, Kasetsart University 5/17

Twisted Pair Cable

Jacket Conductor Wire Dielectric Braided Metal Shield Shield Twisted Pair (STP) Unshield Twisted Pair (UTP)

Applied Network Research Group Department of Computer Engineering, Kasetsart University 6/17

UTP

  • Does not include any extra

shielding around the wire pairs

  • Ordinary telephone line and

commonly used for local area network

  • Least expensive, easy to work

and simple to install

  • Subject to external

electromagnetic interference

  • Limited length
slide-4
SLIDE 4

4

Applied Network Research Group Department of Computer Engineering, Kasetsart University 7/17

STP

  • Covered with a foil shield to

reduce interference and crosstalk

  • Better performance, but

more expensive and difficult to work than UTP

Applied Network Research Group Department of Computer Engineering, Kasetsart University 8/17

Coaxial cable

Center Conductor Insulator Insulating

  • uter cover

Braided outer conductor

slide-5
SLIDE 5

5

Applied Network Research Group Department of Computer Engineering, Kasetsart University 9/17

Optical Fiber

Light wave. High transmission rate. Immune to interference. Light weight.

Optical cladding Plastic coating Optical core

Applied Network Research Group Department of Computer Engineering, Kasetsart University 10/17

Radio Frequency Bands

Radio Communications VLF LF MF HF VHF UHF SHF

3 KHz 30 KHz 300KHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz

EHF ELF VF

30 Hz 300 Hz 3 KHz

Long range Radio Communications AM Radio (540-1660) KHz Ham radio, CB radio, Inter Broadcast VHF TV, FM radio (88-108 MHz) UHF TV, paging, Cellular Radio Microwave, Radar, Satellites Advanced Scientific, experimental

slide-6
SLIDE 6

6

Applied Network Research Group Department of Computer Engineering, Kasetsart University 11/17

Propagation Modes

  • The wave follows

the contour of the earth

  • All transmissions

below about 3 MHz use to travel

Ground Wave: GW Sky Wave : SW Ionosphere

  • SW makes use of the

reflecting properties

  • f the earth’s

atmosphere for the frequencies in the band 3-30 MHz

Line-of-Sight : LOS

  • LOS is used by

frequencies above 30 MHz

  • The waves travel in a

straight line directly from antenna to antenna

Ionosphere

Applied Network Research Group Department of Computer Engineering, Kasetsart University 12/17

Microwave

  • Transmission between two

ground stations

  • Distance ป 50 km (depend on

the height of antennas)

Earth

direct line of sight transmission between two ground stations microwave transmission tower

D=7.14 Kh ; K=4/3

slide-7
SLIDE 7

7

Applied Network Research Group Department of Computer Engineering, Kasetsart University 13/17

Satellites

  • Using microwave
  • Receive and retransmit using

transponder

  • Separate frequencies are

assigned for

  • upward transmission (uplink)
  • downward transmission

(downlink)

earth

uplink downlink footprint sender receiver

Applied Network Research Group Department of Computer Engineering, Kasetsart University 14/17

Satellite Bands

Freq. Band uplink (GHz) downlink (GHz) Purpose 4/6 C 5.925-6.425 3.7-4.2 commercial 7/8 X 7.9-8.4 7.9-8.4 military 11/14 Ku 14.0-14.5 11.7-12.2 commercial 20/30 Ka 27.5-30.5 17.7-21.2 military 20/44 Q 43.5-45.5 20.2-21.32 military

slide-8
SLIDE 8

8

Applied Network Research Group Department of Computer Engineering, Kasetsart University 15/17

Geostationary Satellite

  • Used 3 satellites to cover all
  • ver the earth except the

polar extreme (latitudes > 81

  • north or south).
  • The satellites rotate radially

with the surface of the Earth and therefore remain in a fixed position relative to ground station 24 hours a day.

22,287 miles

  • 180
  • 120
  • 120
  • 120
  • Applied Network Research Group Department of Computer Engineering, Kasetsart University

16/17

Cellular Telephony

Wireless link between fixed terminal point (base station) and terminal.

B S

= Base station = User computer/terminal

B S

Radio field of coverage

  • f base station

F2 F3 F1 F2 F3 F1 F2 F3 F1 F2 F2 F3 F1

F1, F2, F3 = Frequencies used in cell