Presentation on theme: "Data Communication Network"— Presentation transcript:
1 Data Communication Network 331: STUDY DATA COMMUNICATIONS AND NETWORKS
2 331: STUDY DATA COMMUNICATIONS AND NETWORKS 1. Discuss computer networks (5 hrs)2. Discuss data communications (15 hrs)
3 331.2: Discuss Data Communications PERFORMANCE STANDARDGiven a network system, identify and illustrate the different data communications components clearlyObjectives:Define elements of a communication systemDefine data communicationsDiscuss various types of transmission media and their characteristicsDiscuss encoding of information tor transmissionDiscuss types of signal & their characteristicsRelate data capacity of a channel and bandwidthClassify media based on bandwidthDiscuss channel organization
4 Discuss various types of transmission media and their characteristics SKILL AREADiscuss various types of transmission media and their characteristics
5 Types of transmission media twisted pair – telephone cablecoaxial cable –Thick black cable used for higher bandwidth communications than twisted pair (i.e. Optus cable)fibre optic – data transferred through pulses of light. Extremely fast.Non cable methods such as satellite, microwave, wireless and Bluetooth
8 Twisted pair Cable Twisted pair cable application Most common medium Telephone networkBetween house and local exchange (subscriber loop)Within buildingsTo private branch exchange (PBX)For local area networks (LAN)10Mbps or 100Mbps
9 Twisted pair Cable Twisted pair cable pro and contra Advantages Cheap Easy to work withDisadvantagesLow data rateShort range
10 Twisted pair Cable Twisted pair Transmission Characteristics Analog Amplifiers every 5km to 6kmDigitalUse either analog or digital signalsrepeater every 2km or 3kmLimited distanceLimited bandwidth (1MHz)Limited data rate (100MHz)Susceptible to interference and noise
11 Twisted pair Cable Twisted pair (UTP and STP) Unshielded Twisted Pair (UTP)Ordinary telephone wireCheapestEasiest to installSuffers from external EM interferenceShielded Twisted Pair (STP)Metal braid or sheathing that reduces interferenceMore expensiveHarder to handle (thick, heavy)
12 Twisted pair CableThe Electronic Industries Association (EIA) has developed standards to grade UTP.Category 1. The basic twisted-pair cabling used in telephone systems. This level of quality is fine for voice but inadequate for data transmission.Category 2. This category is suitable for voice and data transmission of up to 2Mbps.Category 3.This category is suitable for data transmission of up to 10 Mbps. It is now the standard cable for most telephone systems.Category 4. This category is suitable for data transmission of up to 20 Mbps.Category 5. This category is suitable for data transmission of up to 100 Mbps.
14 ConnectorThe most common UTP connector is RJ45 (RJ stands for Registered Jack).
15 Coaxial Cable Coaxial Cable (or coax) Coaxial cable carries signals of higher frequency ranges than twisted-pair cable.Coaxial Cable standards:RG-8, RG-9, RG-11 are used in thick EthernetRG-58 Used in thin EthernetRG-59 Used for TV
16 Coaxial Cable Coaxial Cable Used for cable television, LANs, telephony Has an inner conductor surrounded by a braided meshBoth conductors share a common center axial, hence the term “co-axial”
19 Coaxial Cable Coaxial Cable Applications: Most versatile medium Television distributionAriel to TVCable TVLong distance telephone transmissionCan carry 10,000 voice calls simultaneouslyBeing replaced by fiber opticShort distance computer systems linksLocal area networks
20 Coaxial Cable Coaxial Cable - Transmission Characteristics Analog Amplifiers every few kmCloser if higher frequencyUp to 500MHzDigitalRepeater every 1kmCloser for higher data rates
21 Fiber Optic Cable Fiber Optic Cable Relatively new transmission medium used by telephone companies in place of long- distance trunk linesAlso used by private companies in implementing local data communications networksRequire a light source with injection laser diode (ILD) or light-emitting diodes (LED)
22 Fiber Optic Cable consists of three concentric sections plastic jacket glass or plasticcladdingfiber core
23 Fiber Optic Cable Fiber Optic Cable Metal cables transmit signals in the form of electric current.Optical fiber is made of glass or plastic and transmits signals in the form of light.Light, a form of electromagnetic energy, travels at 300,000 Kilometers/second (186,000 miles/second), in a vacuum.The speed of the light depends on the density of the medium through which it is traveling (the higher density, the slower the speed).
25 Fiber Optic Types multimode step-index fiber the reflective walls of the fiber move the light pulses to the receivermultimode graded-index fiberacts to refract the light toward the center of the fiber by variations in the densitysingle mode fiberthe light is guided down the center of an extremely narrow core
27 Fiber Optic Advantages greater capacity (bandwidth of up to 2 Gbps)smaller size and lighter weightlower attenuationimmunity to environmental interferencehighly secure due to tap difficulty and lack of signal radiation
28 Fiber Optic Disadvantages expensive over short distancerequires highly skilled installersadding additional nodes is difficult
29 Unguided mediaUnguided media, or wireless communication, transport electromagnetic waves without using a physical conductor.Instead the signals are broadcast though air or water, and thus are available to anyone who has a device capable of receiving them.The section of the electromagnetic spectrum defined as radio communication is divided into eight ranges, called bands.
30 AntennasElectrical conductor (or system of..) used to radiate electromagnetic energy or collect electromagnetic energyTransmissionRadio frequency energy from transmitterConverted to electromagnetic energyBy antennaRadiated into surrounding environmentReceptionElectromagnetic energy impinging on antennaConverted to radio frequency electrical energyFed to receiverSame antenna often used for both
31 Wireless (Unguided Media) Transmission transmission and reception are achieved by means of an antennadirectionaltransmitting antenna puts out focused beamtransmitter and receiver must be alignedomnidirectionalsignal spreads out in all directionscan be received by many antennas
32 Directional AntennaDirectional Antennas provide great efficiency of power transmission because the power can be focused into a narrow beam directed toward the station of interest.
33 Omnidirectional Antenna Omnidirectional Antenna is widely used for radio broadcasting antennas, in mobile devices that use radio such as cell phones, FM radios, walkie-talkies, wireless computer networks, cordless phones, GPS
34 Propagation of Radio Waves Radio technology considers the earth as surrounded by two layers of atmosphere: the troposphere and the ionosphere.The troposphere is the portion of the atmosphere extending outward approximately 30 miles from the earth's surface.The troposphere contains what we generally think of as air. Clouds, wind, temperature variations, and weather in general occur in the troposphere.The ionosphere is the layer of the atmosphere above the troposphere but below space.
36 Propagation of Radio Waves Ground propagation: radio waves travel through the lowest portion of the atmosphere, hugging the earth. These low-frequency signals emanate in all directions from the transmitting antenna and follow the curvature of the planet. The distance depends on the power in the signal.In Sky propagation, higher-frequency radio waves radiate upward into the ionosphere where they are reflected back to earth. This type of transmission allows for greater distances with lower power output.In Line-of-Sight Propagation, very high frequency signals are transmitted in straight lines directly from antenna to antenna.
37 Bands Band Range Propagation Application VLF 3–30 KHz Ground Long-range radio navigationLF30–300 KHzRadio beacons and navigational locatorsMF300 KHz–3 MHzSkyAM radioHF3–30 MHzCitizens band (CB), ship/aircraft communicationVHF30–300 MHzSky and line-of-sightVHF TV, FM radioUHF300 MHz–3 GHzLine-of-sightUHF TV, cellular phones, paging, satelliteSHF3–30 GHzSatellite communicationEHF30–300 GHz
39 Satellite Microwave Satellite is relay station Satellite receives on one frequency, amplifies or repeats signal and transmits on another frequencyRequires geo-stationary orbitHeight of 35,784kmTelevisionLong distance telephonePrivate business networks
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