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Transmission Media

Transmission Media. Lesson 04 NETS2150/2850. Lesson Outline. Wired or guided Media Electromagnetics waves are guided along a solid medium Wireless or unguided media Transmission occurs through atmosphere, outer space or water Understand media characteristics and typical applications.

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Transmission Media

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  1. Transmission Media Lesson 04 NETS2150/2850

  2. Lesson Outline • Wired or guided Media • Electromagnetics waves are guided along a solid medium • Wireless or unguided media • Transmission occurs through atmosphere, outer space or water • Understand media characteristics and typical applications

  3. McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  4. Classes of transmission media McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  5. Electromagnetic Spectrum

  6. Twisted-pair cable Note: Single pair represents one communication link Twisting reduces crosstalk interference between pairs McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  7. UTP and STP McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  8. Categories of unshielded twisted-pair cables McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  9. UTP connector McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  10. Twisted Pair - Applications • Most common medium • Unshielded Twisted Pair (UTP) • Cheapest • Easiest to install • Voice Grade: Telephone wire (Cat 3) • Data Grade: Better quality (Cat 5) • For LAN, 100 Mbps over 100 m possible • Shielded Twisted Pair (STP) • Metal braid reduces interference • More expensive • Harder to handle (thick, heavy)

  11. Coaxial Cable McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  12. Coaxial Cable Applications • Most versatile medium • Television distribution • Arial to TV • Cable TV • Short distance computer systems links • Local area networks

  13. Bending of light ray for transmission McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  14. Optical Fibre

  15. Figure 7.12Propagation modes McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  16. Figure 7.13Modes McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  17. Optical Fibre - Benefits • Great for “noisy”environments! • Tremendous bandwidth • Data rates of hundreds of Gbps • Smaller size & weight • Lower attenuation • Greater amplifier spacing • 40-60 km at least before amplification required for SMF • Used in backbone and high traffic inter-city or inter continent links (submarine cables - undersea)

  18. Wireless transmission waves McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  19. Wireless Spectrum McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  20. Wireless Transmission • 30MHz to 1GHz • Suitable for Omnidirectional • Broadcast radio • 2GHz to 40GHz • Microwave range • Highly directional • Point to point • 3 x 1011 to 2 x 1014 Hz • Infrared range • Used within confined areas

  21. Broadcast Radio • Omnidirectional • FM radio • UHF and VHF television • Requires line of sight

  22. Omnidirectional antennas McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  23. Radio waves are used for broadcast communications, such as radio and television, and paging systems. McGraw-Hill • The McGraw-Hill Companies, Inc., 2004

  24. Terrestrial Microwave • Uses parabolic dish as antenna • Focused beam • Requires line of sight • Used for mobile phones, satellite networks • Higher frequencies give higher data rates

  25. Line of Sight Propagation

  26. Satellite Microwave • Satellite is a relay station • It receives on one frequency (uplink), amplifies or repeats signal and transmits on another frequency (downlink) • Requires geo-stationary orbit • Height of 35,863 km • Applications: • Television live cast • Long distance telephone • Private business networks

  27. Satellite Point to Point Link

  28. Satellite Broadcast Link

  29. Primary Mission: Four-year tour to study Saturn, its rings, moons and magnetosphere Launch:15 October 1997 from Cape Canaveral Air Force Station, Florida Arrival at Saturn:1 July 2004 Distance Travelled:3.5 billion km • NASA.GOV 2004

  30. Infrared • Line of sight (or reflection) • Shirt-range communications • Blocked by walls • e.g. TV remote control, infrared port on printers, laptops, mobile phones, PDAs etc.

  31. Summary • Guide Media • Twisted pair, Coaxial cable, Optical fibre • Unguided or wireless media • Uses antenna as transmitter and receiver (transceiver) • Terrestrial microwave, satellite microwave, Broadcast radio, Infrared • Characteristics and quality determined by medium and signal • For guided transmission, the medium is more important • For unguided, the bandwidth produced by the antenna is more important

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