1 Transmission Media

2 Background Background Guided Media Guided Media Unguided Media Unguided Media

3 Transmission Media Power, voice Radio communication Radio, microwave, satellite Infrared light Ultraviolet light X. Gamma, cosmic rays Visible light, THz 03KHz300 GHz Electromagnetic Spectrum

4 Transmission Media : Background Communication signals are transmitted from one device to another in the form of electromagnetic energy Communication signals are transmitted from one device to another in the form of electromagnetic energy They can travel through a vacuum, air or other transmission media They can travel through a vacuum, air or other transmission media Transmission media are divided into two categories Transmission media are divided into two categories –Guided –unguided

5 Guided Media Coaxial cable Twisted pair cable Fiber-optic cable Unshielded Twisted pair Shielded Twisted pair

6 Twisted-Pair Cable Frequency Range for Twisted-pair cable

7 Unshielded Twisted Pair (UTP) Cable Common type of telecommunication medium in use today Common type of telecommunication medium in use today Its frequency range is suitable for transmitting both data and voice Its frequency range is suitable for transmitting both data and voice Cheap Cheap Flexible and easy to install Flexible and easy to install

8 UTP

9 UTP Categories 5 EIA categories (CAT1-5) 5 EIA categories (CAT1-5) 1  lowest quality, 5  highest quality 1  lowest quality, 5  highest quality CAT1 CAT1 –Basic twisted pair, used in telephone system –Quality is fine for voice Not enough for data communication Not enough for data communication (Low speed) (Low speed)

10 UTP Categories CAT2 CAT2 –Suitable for voice and data communication –Speed is up to 4 Mbps CAT3 CAT3 –Required to have at least 3 twist per foot –Some other requirements –Transmission rate  up to 10 Mbps CAT4 CAT4 –Similar requirement as CAT3 –Transmission rate  up to 16 Mbps CAT5 CAT5 –Transmission rate  up to 100 Mbps

11 UTP Connector The most frequently used is an RJ45 The most frequently used is an RJ45

12 Shielded Twisted Pair (STP)

13 Coaxial Cable

14 Optical Fiber Glass/plastic Glass/plastic Transmits signal in form of light Transmits signal in form of light Nature of light Nature of light –Fastest speed  in vacuum 300,000 km/sec 300,000 km/sec –Refraction

15 Optical Fiber Optical fiber uses reflection to guide light through a channel Optical fiber uses reflection to guide light through a channel A glass or a plastic core is surrounded by a cladding of less dense glass or plastic A glass or a plastic core is surrounded by a cladding of less dense glass or plastic Information is encoded onto a beam of light as a series of on-off flashes that represents 1 and 0 bits Information is encoded onto a beam of light as a series of on-off flashes that represents 1 and 0 bits

16 Propagation Modes Current technology supports two form for propagating light along optical channel Current technology supports two form for propagating light along optical channel –Multimode –Single mode Multimode Multimode –Multiple beams move through the core in different paths Single Mode Single Mode

17 Multimode Multimode Graded-Index Multimode Step-Index

18 Single Mode

19 Fiber Construction

20 Fiber Sizes Defined by the ratio of diameter of the core to the diameter of the cladding (micrometers) Defined by the ratio of diameter of the core to the diameter of the cladding (micrometers) Common sizes are Common sizes are Fiber Type Core (microns) Cladding (microns) 62.5/ / / /

21 Fiber Optic Advantages Noise resistance Noise resistance –Noise is not a factor to light –External light is blocked from the channel by the outer jacket Less signal attenuation Less signal attenuation –Transmission distance is greater than other media –A signal can run for a long distance without requiring regeneration

22 Fiber Optic Advantages Higher Bandwidth Higher Bandwidth –Supports higher bandwidth than other media –Data rate is also high –The limitation of data rate and bandwidth depends on the signal generation and reception technology

23 Fiber Optic Disadvantages Cost Cost Installation/Maintenance Installation/Maintenance Fragility Fragility