![Coaxial Cable
• Discussion divided into two basic categories for coax
used in LANs:
• 50-ohm cable [baseband]
• 75-ohm cable [broadband or single channel baseband]
• In general, coax has better noise immunity for higher
frequencies than twisted pair.
• Coaxial cable provides much higher bandwidth than
twisted pair.
• However, cable is ‘bulky’.
Pranoti
R.
Doke](https://image.slidesharecdn.com/unit3cndphysicallayertransmissionmediumpranotidoke-210517071533/85/Unit-3-_CND_22634_-physical-layer_transmission-medium_pranoti-doke_MSBTE-21-320.jpg)
Unit 3 _CND_22634_ physical layer_transmission medium_pranoti doke_MSBTE
- 1. Physical Layer: Transmission Medium Pranoti R. Doke Pranoti R. Doke
- 2. Transmission Media Transmission medium:: the physical path between transmitter and receiver. • Repeaters or amplifiers may be used to extend the length of the medium. • Communication of electromagnetic waves is guided or unguided. ❑ Guided media: Waves are guided along a physical path (e.g, twisted pair, coaxial cable and optical fiber) ❑ Unguided media: Media Meant for transmitting but not guiding electromagnetic waves (e.g., the atmosphere and outer space). Pranoti R. Doke
- 3. Transmission Media Choices • Twisted pair • Coaxial cable • Optical fiber • Wireless communications Pranoti R. Doke
- 4. Types of Transmission Media Transmission Media Guided Media Unguided Media Pranoti R. Doke
- 5. Figure Transmission medium and physical layer Transmission medium and physical layer Pranoti R. Doke
- 6. Figure Classes of transmission media Classes of Transmission Media Pranoti R. Doke
- 7. 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. Pranoti R. Doke
- 8. Guided Media Guided media are the physical links through which signals are confined to narrow path. These are also called guide media. Bounded media are made up o a external conductor (Usually Copper) bounded by jacket material. Bounded media are great for LABS because they offer high speed, good security and low cast. However, some time they cannot be used due distance communication. Three common types of bounded media are used of the data transmission. These are Coaxial Cable Twisted Pairs Cable Fiber Optics Cable Pranoti R. Doke
- 9. Twisted Pair • Two insulated wires arranged in a spiral pattern • Copper or steel coated with copper • The signal is transmitted through one wire and a ground reference is transmitted in the other wire. • Typically twisted pair is installed in building telephone wiring. • Local loop connection to central telephone exchange is twisted pair. Pranoti R. Doke
- 10. Twisted Pair • Limited in distance, bandwidth and data rate due to problems with attenuation, interference and noise • Issue: cross-talk due to interference from other signals • “shielding” wire (shielded twisted pair (STP)) with metallic braid or sheathing reduces interference. • “twisting” reduces low-frequency interference and crosstalk. Pranoti R. Doke
- 11. Shielded twisted pair (STP) an d Unshielded twisted pair (UTP) • Cables with the shield are called shielded twisted pair and commonly abbreviated STP. • Cables without a shield are called unshielded twisted pair or UTP. • Twisting the wires together results in characteristics impedance for the cable. • UTP or unshielded twisted pair cable is used on Ethernet • UTP cables are used for Ethernet cabling where 4 twisted pair cables (a total of 8 wires are used) Pranoti R. Doke
- 12. Unshielded twisted pair (UTP) Cables with the shield are called shielded twisted pair and commonly abbreviated STP. Cables without a shield are called unshielded twisted pair or UTP. Twisting the wires together results in characteristics impedance for the cable. UTP or unshielded twisted pair cable is used on Ethernet UTP cables are used for Ethernet cabling where 4 twisted pair cables (a total of 8 wires are used) Pranoti R. Doke
- 13. Shielded twisted pair (STP) It is similar to UTP but has a mesh shielding that’s protects it from EMI which allows for higher transmission rate. Pranoti R. Doke Unshielded twisted pair (UTP) UTP is more common. It can be either voice grade or data grade depending on the condition. UTP cable normally has an impedance of 100 ohm. UTP cost less than STP and easily available due to its many use. There are five levels of data cabling.
- 14. Figure Twisted-pair cable Twisted-Pair cable Pranoti R. Doke
- 15. Figure UTP and STP cables UTP and STP cables Pranoti R. Doke
- 16. Shielded twisted pair (STP) and UTP Cable (Non Shielded) Pranoti R. Doke
- 17. Shielded twisted pair (STP) and UTP Cable (Non Shielded) Pranoti R. Doke
- 18. Figure UTP connector UTP connector Pranoti R. Doke
- 19. Figure Coaxial cable Coaxial Cable Pranoti R. Doke
- 20. Center conductor Dielectric material Braided outer conductor Outer cover Copyright ©2000 The McGraw Hill Companies Coaxial Cable Pranoti R. Doke
- 21. Coaxial Cable • Discussion divided into two basic categories for coax used in LANs: • 50-ohm cable [baseband] • 75-ohm cable [broadband or single channel baseband] • In general, coax has better noise immunity for higher frequencies than twisted pair. • Coaxial cable provides much higher bandwidth than twisted pair. • However, cable is ‘bulky’. Pranoti R. Doke
- 22. Coaxial Cable • Coaxial cable consists of 2 conductors. • The inner conductor is contained inside the insulator with the other conductor weaves around it providing a shield. • An insulating protective coating called a jacket covers the outer conductor. • The outer shield protects the inner conductor from outside electrical signals. • The distance between the outer conductor (Shield) and inner conductor plus the type of material used for insulating the inner conductor determine the cable properties or impedance. The excellent control of the impedance characteristics of the cable allow higher data rates to be transferred than twisted pair cable. Pranoti R. Doke
- 23. Coaxial cable Coaxial cable is very common & widely used commutation media. For example TV wire is usually coaxial. Coaxial cable gets its name because it contains two conductors that are parallel to each other. The center conductor in the cable is usually copper. The copper can be either a solid wire or stranded martial. Outside this central Conductor is a non-conductive material. It is usually white, plastic material used to separate the inner Conductor form the outer Conductor. The other Conductor is a fine mesh made from Copper. Pranoti R. Doke
- 24. Optical Fiber • Optical fiber: A thin flexible medium capable of conducting optical rays. Optical fiber consists of a very fine cylinder of glass (core) surrounded by concentric layers of glass (cladding). • A signal-encoded beam of light (a fluctuating beam) is transmitted by total internal reflection. • Total internal reflection occurs in the core because it has a higher optical density (index of refraction) than the cladding. • Attenuation in the fiber can be kept low by controlling the impurities in the glass. Pranoti R. Doke
- 25. Optical Fiber • Optical fiber consists of thin glass fiber that can carry information at frequencies in the visible light spectrum. • The typical optical fiber consists of a very narrow strand of glass called the cladding. • A typical core diameter is 62.5 microns. Typically cladding has a diameter of 125 minors. Coating the cladding is a protective coating consisting of plastic, it is called the jacket. • The device generating the message has it in electromagnetic form (electrical signal); this has to be converted into light (i.e. optical signal) to send it on optic fiber cable. The process of converting light to electric signal is done on the receiving side. Pranoti R. Doke
- 26. Fiber optic cable Fiber optic cable uses electrical signals to transmit data. It uses light. In fiber optic cable light only moves in one direction for two way communication to take place a second connection must be made between the two devices. It is actually two stands of cable. Each stand is responsible for one direction of communication. A laser at one device sends pulse of light through this cable to other device. These pulses translated into “1’s” and “0’s” at the other end. In the center of fiber cable is a glass stand or core. The light from the laser moves through this glass to the other device around the internal core is a reflective material known asCLADDING. No light escapes the glass core because of this reflective cladding. Pranoti R. Doke
- 27. core cladding jacket light c (a) Geometry of optical fiber (b) Reflection in optical fiber Optical Fiber Leon-Garcia & Widjaja: Communication Networks Copyright ©2000 The McGraw Hill Companies Pranoti R. Doke
- 28. Figure: Optical fiber Optical fiber Pranoti R. Doke
- 29. Figure: Fiber optics: Bending of light ray Fiber optics: Bending of light ray Pranoti R. Doke
- 30. Figure : Fiber construction Fiber construction Pranoti R. Doke
- 31. Figure : Fiber-optic cable connectors Fiber-optic cable connectors Pranoti R. Doke
- 32. Figure Propagation modes Propagation Modes Pranoti R. Doke
- 33. Figure Modes Modes of Propogation Pranoti R. Doke
- 35. UNGUIDED MEDIA: WIRELESS Unguided media transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication. Radio Waves Microwaves Infrared Topics discussed in this section: Pranoti R. Doke
- 36. Unguided Media • Unguided media or wireless media doesn't use any physical connectors between the two devices communicating. Usually the transmission is send through the atmosphere but, sometime it can be just across the rule. Wireless media is used when a physical obstruction or distance blocks are used with normal cable media. The three types of wireless media are: Radio waves Micro waves Infrared waves Pranoti R. Doke
- 37. Unguided Media • Unguided media transport data without using a physical conductor. This type of communication is often referred to as wireless communication. It uses wireless electromagnetic signals to send data. • There are three types of Unguided Media (i) Radio waves (ii) Micro waves (iii) Infrared. • These signals can be sent or propagated in the following three ways: 1. Ground-wave propagation 2. Sky-wave propagation 3. Line-of-sight propagation Pranoti R. Doke
- 38. Figure Wireless transmission waves Wireless transmission waves Pranoti R. Doke
- 39. Ground-wave Propagation • In this type of way, the signals are transmitted in the lowest layer of the atmosphere and can be sent in all directions using the antenna as a transmitting device. The signals are transmitted as the frequency is lower for this signal. • Characteristics of Ground-wave propagation are as follows: i. Follows contour of the earth ii. Can Propagate considerable distances iii. Frequencies up to 2 MHz iv. Example a. AM radio Pranoti R. Doke
- 41. Sky Wave Propagation In this type of way, the signals are transmitted that has usually high- frequency and can be transmitted using the sky as a medium. In this way, the radio waves are transmitted in the upward direction and then signals get reflected because of the ionosphere and reach to earth surface again. By this, the signals can be transmitted for longer distances consuming less power. Characteristics of Sky Propagation are as follows: • i. Signal reflected from ionized layer of atmosphere back down to earth • ii. Signal can travel a number of hops, back and forth between ionosphere and earth‘s surface • iii. Reflection effect caused by refraction iv. Examples a. Amateur radio b. CB radio Pranoti R. Doke
- 43. Line of Sight Propagation In this type of way, the signals having a very high frequency is transmitted using the antenna to antenna communication. Characteristics i. Transmitting and receiving antennas must be within line of sight a. Satellite communication – signal above 30 MHz not reflected by ionosphere b. Ground communication – antennas within effective line of site due to refraction Pranoti R. Doke
- 44. Line of Sight Propogation Pranoti R. Doke
- 45. Figure : Electromagnetic spectrum for wireless communication Electromagnetic spectrum for wireless communication Pranoti R. Doke
- 46. Figure : Propagation methods Propagation Methods Pranoti R. Doke
- 47. Figure : Propagation methods Propagation Methods Pranoti R. Doke
- 48. Figure : Propagation methods Propagation Methods Pranoti R. Doke
- 49. Propagation Methods Pranoti R. Doke Radio waves application: 1.The radio waves are used where there is a requirement of sending the same information to multiple users from a single source. 2.The applications of radio waves are television, FM radio, and cordless phone. Microwave application: 1.The unicast transmission becomes easier using microwave transmission. 2.The microwaves are used in satellite network communication and wireless LANs.
- 50. Propagation Methods Pranoti R. Doke Infrared application: 1.The data transmission quality for the infrared is comparatively higher than other types of electromagnetic waves. 2.Used in computer system components to have communication between them.
- 51. Advantages of Unguided Media Transmission Pranoti R. Doke There are several advantages of unguided media transmission. 1. The bandwidth of unguided media transmission is higher when it is compared to guided transmission media. The information can be shared without having any disturbance from any medium. 2. The unguided transmission media does not get affected by corrosive materials as there is no direct communication between the sender node and the destination node. 3. The price of unguided media transmission is lower compared to guided transmission media as there are no physical cables or wires used which help to reduce the setup cost for the unguided transmission medium.
- 52. Pranoti R. Doke 4. A single time, the same information can be broadcast to multiple users without having any delay. For example, broadcast of radio or tv channels in which multiple users can use the device for getting information. 5. The signals in unguided transmission media can be transmitted for long distances without having any disturbance from medium and without compromising quality. 6. The signal attenuation is lower in the unguided transmission medium. As there is no physical wire or cable used the attenuation is lower in information transmission. Advantages of Unguided Media Transmission
- 53. Figure : Propagation methods Propagation Methods Pranoti R. Doke
- 54. Figure : Propagation methods Propagation Methods Pranoti R. Doke
- 55. Figure : Propagation methods Propagation Methods Pranoti R. Doke
- 57. Thank You