More Related Content
Similar to Lecture .06 media (20)
Lecture .06 media
- 1. Transmission Media 1 Course Instructor: Salahuddin MS/Mphill in Computer and Networking Lecturer in GC Upper Dir
- 2. Content 2 Transmission Media Guided Media: T wisted Pair UTP STP Co-Axial Cable Fibre Optic Cable Propagartion Modes Transmission Impairment Unguided Media: Propagation Methods Radio Waves Antenna Microwaves Infrared
- 3. What is Tranmission Media ? 3 I n data communication, • Transmission media isa pathway that carries the information from sender to receiver. • We use different types of cables or waves to transmit data. • Data is transmitted normally through electrical or electromagnetic signals.
- 4. Description • Transmission media are located below the physical layer • Computers use signals to represent data. • Signals are transmitted in form of electromagnetic energy. 4
- 5. Classification of Transmission media 7
- 6. Twisted-pair cable Atwisted pair consists of two conductors Basically copper based With its own plastic insulation, twisted together. 6
- 7. Twisted Pair Description • Provide protection against cross talk or interference(noise) • One wire use to carry signals to the receiver • Second wire used as a ground reference • For twisting, after receiving the signal remains same. • T herefore number of twistsper unit length, determines the quality of cable. 7
- 8. Twisted Pair Advantages: • Cheap • Easy to work with Disadvantages: • Low data rate • Short range 8
- 9. Twisted Pair - Applications • Very common medium • Can be use in telephone network • Connection Within the buildings • For local area networks (LAN) 9
- 10. Twisted Pair Cables Twisted Pair cables Unshielded Twisted Pair (UTP) Shielded Twisted pair (STP) 10
- 11. Unshielded Twisted Pair (UTP): Description • Pairof unshielded wires wound around each other • Easiest to install 11
- 12. Applications UTP : Telephone subscribers connect to the central telephone office DSL lines LAN – 10Mbps or 100Mbps 12
- 13. UTP Cable Types Cat 6 13 Cat 5e Cat 5 Cat 4 Cat 3 Cat 1 Cat 7 Cat 2 UTP Cat means category according to IEEE standards. IEEE is de jure standard
- 14. Categories of UTP cables 14
- 15. UTP connector and Tools RJ45 (RJ stands for registered jack) is a keyed connector, it means that it can be inserted in only one way Crimper Tool 15
- 16. Advantages of UTP: Affordable Most compatible cabling Major networking system Disadvantages of UTP: • Suffers from external Electromagnetic interference 16
- 17. Shielded Twisted Pair (STP) • Pair of wires wound around each other placed inside a protective foil wrap • Metal braid orsheath foil that reduces interference • Harder to handle (thick, heavy) 17
- 18. STP Application • STP is used in IBM token ring networks. • Higher transmission rates over longer distances. 18
- 19. Advantages of STP: Shielded Faster than UT P Disadvantages of STP: More expensive than UT P High attenuation rate 19
- 20. Co-axial cable carries signal of higher frequency ranges than twisted pair cable Co-axial Cable • Inner conductor isa solid wire • Outer conductor serves as a shield against noise and a second conductor 20
- 21. Categories of coaxial cables Coaxial cables are categorized by Radio Government (RG) ratings, RG is De Jure standards 21
- 22. Coaxial Cable Applications • Most versatile medium • T elevision distribution • Long distance telephone transmission • Can carry 10,000 voice calls simultaneously • Short distance computer systems links • Local area networks 22
- 23. ADVANTAGES Easy to wire Easy to expand Moderate level of Electro Magnetic Interference DISADVANTAGE Single cable failure can take down an entire network Cost of installation of a coaxial cable is high due to its thicknessand stiffness Cost of maintenance isalso high COAXIAL CABLE 23
- 24. Fiber-Optic Cable Afiber optic cable is made of glass or plastic and transmit signals in the form of light. A fiber-optics cable consists of hundreds or thousands of thin strands of glass that transmit pulsating beams of light instead of electricity. It is thinner than a human hair. Data transfer rate of fiber optics is very fast. There is no chance of data loss. Light pulse is not affected by random electromagnetic interference in the environment. They have much lower error rates that normal telephone twisted pair or coaxial cable. Nature of light: Light travels in a straight line If light goes from one substance to another then the ray of light changes direction Ray of light changes direction when goes from more dense to a less dence substance 24
- 25. Bending of light ray • Angle of Incidence (I): the angle the ray makeswith the line perpendicular to the interface between the two substances • Critical Angle:the angle of incidence which providesan angle of refraction of 90-degrees. 28
- 26. Optical fiber • Uses reflection to guide light through a channel • Core isof glassor plastic surrounded by Cladding • Cladding isof less dense glassor plastic An optical fiber cable has a cylindrical shape and consists of three concentric sections: the core, the cladding, and the jacket(outer part of the cable). Jacket 26
- 28. Fiber –Optic cable Connectors 28 Subscriber Channel (SC) Connecter Straight-Tip (ST) Connecter Same szie as RJ45 connector
- 29. OFC Propagation Modes Propagation Modes Multimode Single Mode Step -Index Graded - Index When signal goes from one point to another there are need for propagation modes. 29
- 33. Areas of Application Telecommunications Local Area Networks Cable T V CCTV Medical Education 33
- 34. Optical Fiber Advantages Greater capacity Example: Data rates at 100 Gbps Smaller size & light weight Lower attenuation Electromagnetic isolation More resistance to corrosive materials Greater repeater spacing facility Example: After every 10sof km at least 34
- 35. Optical Fiber Disadvantages • I nstallation and maintenance need expertise • Only Unidirectional light propagation • Much more expensive 35
- 36. Transmission Impairment • The Imperfection in transmission media causes signal impairment • What issent isnot what isreceived due to impairment • T hree causes of impairement are 1)Attenuation, 2)Distortion 3)Noise ATTENUATION DISTORTION NOISE 36
- 37. • Attenuation means a loss of energy. • Distortion means that the signal changes its form or shape. • Noise isanother cause of impairement. • Several types of noise Example:thermal noise, induced noise, crosstalk Transmission Impairment 37
- 38. Unguided Media:Wireless Transmission 3 kHz 38 300GHz 400THz 900THz Unguided media transport electromagnetic waves without using a physical conductor it is known as wireless communication. Signals broadcast through free space and available to capable receiver Electro magnetic spectrum for wireless communication: Radio wave & Micro wave Infrared
- 39. Propagation methods Unguided signals travels from the source to destination in several ways it is known as propagation. They are three types: Ground propagation Sky propagation Line-of-Sight Propagation 39
- 40. Ground propagation: Radio waves travel through the lowest portion of the atmosphere T ouching the earth. Sky propagation: Radio waves radiate to the ionosphere then they are reflected back to earth. Line-of-Sight Propagation: Instraight lines directly from antenna to antenna. 40
- 41. Bands using propagation method Band Range Propagation Application VLF 3–30 KHz Ground Long-range radio navigation LF 30–300 KHz Ground Radio beacons and navigational locators MF 300 KHz–3 MHz Sky AM radio HF 3–30 MHz Sky Citizens band (CB), ship/aircraft communication VHF 30–300 MHz Sky and line-of-sight VHF TV, FM radio UHF 300 MHz–3 GHz Line-of-sight UHF TV, cellular phones, paging, satellite SHF 3–30 GHz Line-of-sight Satellite communication EHF 30–300 GHz Line-of-sight Long-range radio navigation 41
- 42. Unguided Media Wireless transmission waves 42
- 43. Omnidirectional Antenna Frequencies between 3 KHz and 1 GHz. Used for multicasts(multiple way) communications, such as radio and television, and paging system. Radio waves can penetrate buildings easily, so that widely use for indoors& outdoors communication. Unguided Media – Radio Waves 43
- 44. Microwaves are ideal when large areas need to be covered and there are no obstacles in the path Microwaves 44
- 45. Micro waves Transmission • Microwaves are unidirectional • Micro waves electromagnetic waves having frequency between 1 GHZ and 300 GHZ. • There are two types of micro waves data communication system :terrestrial and satellite • Micro waves are widely used for one to one communication between sender and receiver, example: cellular phone, satellite networks and in wireless LANs(wifi), WiMAX,GPS 45
- 46. Infrared Frequencies between 300 GHz to 400 THz. Used for short-range communication. Use for line of sight communication. Example: Night Vision Camera,Remote control, File sharing between two phones, Communication between a PC and peripheral device, 46
- 47. continue BASIS FOR COMPARISON GUIDED MEDIA UNGUIDED MEDIA Basic The signal requires a physical path for transmission. The signal is broadcasted through air or sometimes water. Alternative name It is called wired communication or bounded transmission media. It is called wireless communication or unbounded transmission media. Direction It provides direction to signal for travelling. It does not provide any direction. Types Twisted pair cable, coaxial cable and fibre optic cable. Radio wave, microwave and infrared.
- 48. Any Question ?