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Transmission Media

Transmission Media. Figure 7.1 Transmission medium and physical layer. Figure 7.2 Classes of transmission media. 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.

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Transmission Media

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  1. Transmission Media

  2. Figure 7.1 Transmission medium and physical layer

  3. Figure 7.2 Classes of transmission media

  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. Topics discussed in this section: Twisted-Pair CableCoaxial CableFiber-Optic Cable

  5. Figure 7.3 Twisted-pair cable

  6. Figure 7.4 UTP and STP cables

  7. Table 7.1 Categories of unshielded twisted-pair cables

  8. Figure 7.5 UTP connector

  9. Figure 7.6 UTP performance

  10. Figure 7.7 Coaxial cable

  11. Table 7.2 Categories of coaxial cables

  12. Figure 7.8 BNC connectors

  13. Figure 7.9 Coaxial cable performance

  14. Figure 7.10 Bending of light ray

  15. Figure 7.11 Optical fiber

  16. Figure 7.12 Propagation modes

  17. Figure 7.13 Modes

  18. Table 7.3 Fiber types

  19. Figure 7.14 Fiber construction

  20. Figure 7.15 Fiber-optic cable connectors

  21. Figure 7.16 Optical fiber performance

  22. 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. Topics discussed in this section: Radio Waves Microwaves Infrared

  23. Figure 7.17 Electromagnetic spectrum for wireless communication

  24. For transmission (wireless) • Antenna plays a key role • Two types of transmission • Transmitting antenna puts out a focused electromagnetic beam • Transmitter and receiver should be carefully aligned • Allows point to point communication • Transmitter signals spreads in all directions • Can be received by many antennas • Broadcast communication

  25. Figure 7.18 Propagation methods Example: TV, Cellular Phone Example: AM radio Example: SW radio

  26. Figure 7.19 Wireless transmission waves

  27. Figure 7.20 Omnidirectional antenna

  28. Note Radio waves are used for multicast communications, such as radio and television, and paging systems.

  29. Microwaves

  30. Figure 7.21 Unidirectional antennas

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

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

  33. Microwaves Types • Terrestrial Microwaves • Long-Haul communication • Maximum distance in KM d=7.14*sqroot(Kh) • 100m antenna  82KM distance • Attenuation • Attenuation increases with rainfall • Satellite Microwaves • Increase the height by fixing antenna in a satellite

  34. Infrared Communication

  35. IrDA

  36. Classical satellite systems Inter Satellite Link (ISL) Mobile User Link (MUL) MUL Gateway Link (GWL) GWL small cells (spotbeams) base station or gateway footprint GSM ISDN PSTN User data PSTN: Public Switched Telephone Network

  37. Satellites in circular orbits attractive force Fg = m g (R/r)² centrifugal force Fc = m r ² m: mass of the satellite R: radius of the earth (R = 6370 km) r: distance to the center of the earth g: acceleration of gravity (g = 9.81 m/s²) : angular velocity ( = 2  f, f: rotation frequency) Stable orbit Fg = Fc Basics

  38. Orbits GEO (Inmarsat) HEO MEO (ICO) LEO (Globalstar,Irdium) inner and outer Van Allen belts earth 1000 10000 35768 km

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