4 The coaxial cable The most widely used network cabling. it is inexpensive.LightFlexibleEasy to work with.
5 The coaxial cable The coaxial cable consist of : Core consist of solid copper surrounded by insulation, braided metal shielding and an outer cover for protection.
6 The coaxial cableShielding protects transmitted data by absorbing the noise.The core of coaxial cable carries the electronic signals which make up data.The core wire can be either solid or copper.
7 The coaxial cableThe core is surrounded by a dielectric insulation which separate it from the wire mesh.The wire mesh protects the wire core from the noise and crosstalk.Crosstalk is signal overflow from an adjacent wire.The entire cable is surrounded by a non-conducting outer shield, made from rubberor plastic.
8 The coaxial cableThe coaxial cable is good for longer distances and for reliably supporting higher data rates with less sophisticated equipment.
9 Types of coaxial cableThin (thinnet).Thick (thicknet).
10 Coaxial cable consideration It is used when you need:A medium that will transmit voice, video and data.To transmit data longer distances than less expensive cabling can doData security.
11 Twisted pair cableIt consists of two insulated strands of copper wire twisted around each other.The twisting cancels out the electronic noise from adjacent pairs and from other sources .
13 Unshielded twisted pair cable (UTP) It is the most popular type of twisted-pair and also the most popular one for LAN cabling.The maximum cable length for this type is 100 meters.It consist of two unshielded copper wires.
14 Shielded twisted pair cable (STP). This type uses a jacket which is a higher-quality and more protective than UTP.It uses a foil wrap between and around the wire pairs.Therefore, STP is excellent in protecting data from outside interference.
15 Twisted pair cabling components Hardware connection:RJ-45RJ-11RJ-45 differ from RJ-11 in that it is larger, and will not fit in the RJ-11 telephone jackt.RJ-45 houses eight cable connections while RJ-11 houses only four .
17 Twisted pair cabling consideration Use Twisted pair if:Budget limitation.Easy installation is required.Do not use it if :High data integrity is required with high speed and long distance.
18 Fiber-optic cableIn this kind of cables, optical fibers carry digital data signals in a form of modulatedpulses of light.It is more safe than other kinds of cables, because no electronic impulses are carried over the fiber-optic cable.Therefore, data can’t be stolen.
19 Fiber-optic cable It consist of : outer jacket Kevlar strands to strength the cablePlastic coating to cushion the fiberThe fiber is at the center consist of cladding and core
20 Fiber-optic cableEach glass strand passes signals in only one direction. Therefore, a cable consist of two strands one for sending and one for receiving data.
21 Fiber-optic consideration Use fiber-optic if:Need to transmit data in a high speed over long distance. In a very secure media .Don’t use it if:tight budget.Don’t have the expertise available to install it properly.
22 Wireless Transmission Unguided Media: transport electromagnetic waves without the use of a physical conductor.Transmission is sent and received through invisible wavesLess expensive than copper or fiber optic lines.Allows the user to move freely around the office or campus and still remain connected to the networkFastest-growing segment of network media today
24 Radio wavesRadio waves are omnidirectional. The radio wave band is under government regulation.Radio waves are used for multicast communications, such as radio and television, and paging systems.Frequencies range between 3 KHz and 1 GHz.
25 2. Microwavesconsist of number of dishes installed on high towers or high placesdistance must be 50 kilometers or less.Its fast but it may have noise and interferenceMicrowaves are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs
26 3. Infrared Frequencies between 300 GHz to 400 Thz. Can not penetrate walls.Infrared signals can be used for short-range communication in a closed area.
27 Signal TransmissionThere are two techniques used to transmit the encoded signals over cable:BasebandBroadband
28 I. Baseband Signaling Sends one data signal across the network media. Entire capacity of the media is used for the one data signalSignals are transmitted in a digital format .Many devices can send and receive across the medium, but only one at a time.Baseband:Uses Digital SignalingSingle FrequencyTransmits Bi-directionallyUses Repeaters
30 II. Broadband Signaling Divides the cable into several different channels.Signals are transmitted at different frequencies in an analog mode.Allows many different signals to be sent simultaneously on a single cable.Signal sent in only one direction.Used for computer network data transmissions.BroadbandUses Analog SignalingMultiple FrequenciesTransmits Uni-directionallyUses Amplifiers
32 Factors Affecting Transmissions The flow of a signal down the network media can become distorted.Common types of distortions are:attenuationinterference.
33 a) Attenuation Loss of signal power Measured by the decrease in decibels (db) over a specific distance
34 b) InterferenceInterference is caused when a strong external signal interferes with a signal.Radio frequency interference (RFI) - interference caused by broadcast signals from a radio or television transmitter.Electromagnetic interference (EMI) - motor or source of intense electrical activity creates an electromagnetic signal that interferes with a data signal.Near end crosstalk (NEXT) and Far end crosstalk (FEXT) - interference from another data signal being transmitted on adjacent wire.